Observing Archives

August 12, 2012December 23, 2015 by Tammy Plotner

Weekly SkyWatcher’s Forecast: August 13-19, 2012

Greetings, fellow SkyWatchers! Even if you missed the peak of the Perseid meteor shower, there will still be plenty of “strays” to sparkle this week’s dark nights. For astronomy without a telescope, be sure to check out all the planetary alignments – and tell your friends! When you’re ready to learn more about what to view and when this week, then meet me in the back yard…

Monday, August 13 – Celestial scenery alert! If you’re out before dawn this morning, look for the very close pairing of Venus and the slender crescent Moon. For viewers in the north-eastern Asia area, this is an occultation event, so be sure to check resources for times and locations in your area! How about some more eye candy? Then check out the splendid alignment of Saturn, Mars and Spica just after sky dark. Look for the blue/white star to the west, accompanied by red Mars to the east and yellow Saturn even higher to the east. The trio will be roughly separated by the same distance from each other and the colors will be a welcome sight. Be sure to alert your family and friends to all the celestial action that doesn’t require a telescope today!

Tonight, begin with just your eyes as you gaze about four fingerwidths above the top of the Sagittarius “teapot dome” for an open window on the stars and mighty M24 (Right Ascension: 18 : 18.4 – Declination: -18 : 25)…

This huge, hazy patch of stars is in reality an area of space known as “Baade’s Window” – an area free of obscuring gas and dust. Cataloged by Messier in 1764 as object 24, even small binoculars will reveal the incredible vista of the “Sagittarius Star Cloud.” Although it’s actually not a cluster, but rather a clean view of an area of our own galaxy’s spiral arm, that will not lessen the impact when viewed through a telescope. Spanning a degree and a half of sky, it is one of the few areas in which even a novice can easily perceive areas of dark dust.

For larger telescopes, look for the dim, open cluster NGC 6603 (Right Ascension: 18 : 18.4 – Declination: -18 : 25) in the northeastern position of the Window. There are two very notable dark nebulae, B92 and B93, located in the northern segment as well. Near teardrop shaped B92 and its single central star, you should spot open cluster Collinder 469 and also Markarian 38 south of B93. You’ll find B86 near Gamma Sagittarii . At the southern edge of the star cloud, look for emission nebula IC 1283-1284, along with the reflection nebulae NGC 6589 (Right Ascension: 18 : 16.9 – Declination: -19 : 46) and NGC 6590 (Right Ascension: 18 : 17.0 – Declination: -19 : 53) and open cluster NGC 6595 (Right Ascension: 18 : 17.0 – Declination: -19 : 53). Still up for more? Then head west to see if you can find 12th-magnitude planetary nebula NGC 6567 (Right Ascension: 18 : 13.7 – Declination: -19 : 05).

Even if you don’t accept these challenges, you can still enjoy looking at a 560 light-year swatch of stars from one of the Milky Way’s loving arms! (If you’re out late, look for Mira… It was discovered by Fabricius on this date in 1596.)

Tuesday, August 14 – Celestial scenery alert! Be out just after sunset to catch a splendid stellar and planetary conjunction. To the west you’ll see bright Spica. Just above it, Mars. And just above that? Saturn! The trio are all separated by just a few degrees, so be sure to stop and enjoy!
Your first challenge for tonight will be to venture about three fingerwidths northeast of Lambda Sagittarii to visit a well-known but little visited galactic cluster – M25 (Right Ascension: 18 : 31.6 – Declination: -19 : 15).

First discovered by Cheseaux and then cataloged by Messier, it was observed and recorded by William Herschel, Johann Elert Bode, Admiral Smythe and T. W. Webb…but never added to the NGC catalog of John Herschel! Thanks to J.L.E. Dreyer, it did make the second Index Catalog as IC 4725.

Seen with even the slightest optical aid, this 5th magnitude cluster contains two G-type giants as well as a Delta Cephei-type variable with the designation of U, which changes about one magnitude in a period of less than a week. It’s very old for an open cluster, perhaps near 90 million years, and the light you see tonight left the cluster over 2000 years ago. While binoculars will see around a double handful of bright stars overlaying fainter members, telescopes will reveal more and more as aperture increases. At one time it was believed to have only about 30 members, but this was later revised to 86. But recent studies by Archinal and Hynes indicate it may have as many as 601 member stars!

Wednesday, August 15 – Celestial scenery alert! Get up before dawn to spot Mercury low on the eastern horizon, a very tiny crescent Moon to its west/southwest and brilliant Venus ruling above it all! To add to the mix, you’ll see the pairing of the Gemini Twins – Castor and Pollux – just about a handspan above Mercury and luminous Procyon about the same distance due south. If you missed your opportunity to view Spica, Mars and Saturn on Monday, don’t worry. The colorful trio is still around tonight just after sky dark to the west, but now you can see that Mars has moved slightly to the south. Ain’t celestial mechanics grand?!

Tonight we’ll head back to Scorpius to have a look at three pristine open clusters. Begin your starhop at the colorful southern Zeta pair and head north less than one degree for NGC 6231 (Right Ascension: 16 : 54.0 – Declination: -41 : 48).

Wonderfully bright in binoculars and well resolved to the telescope, this tight open cluster was first discovered by Hodierna before 1654. De Cheseaux cataloged it as object 9, Lacaille as II.13, Dunlop as 499, Melotte as 153, and Collinder as 315. No matter what catalog number you chose to put in your notes, you’ll find the 3.2 million year young cluster shining as the “Northern Jewelbox!” For high power fans, look for the brightest star in this group – it’s van den Bos 1833, a splendid binary.

About another degree north is loose open cluster Collinder 316, with its stars scattered widely across the sky. Caught on its eastern edge is another cluster known as Trumpler 24, a site where new variables might be found. This entire region is encased in a 90 arc minute faint emission nebula called IC 4628 (Right Ascension: 16 : 57.0 – Declination: -40 : 20) – making this low power journey through southern Scorpius a red hot summer treat!

Thursday, August 16 – If you did not get a chance to look at the Northern Jewelbox region in Scorpius, return again and sweep the area tonight. For those with larger telescopes, we’re going to hop about a degree and a half south of twin Nu for NGC 6242 (Right Ascension: 16 : 55.6 – Declination: -39 : 30).

Discovered by Lacaille and cataloged as I.4, it is also known as Dunlop 520, Melotte 155 and Collinder 317. At roughly magnitude 6, this open cluster is within binocular range, but truly needs a telescope to appreciate its fainter stars. While NGC 6242 might seem like nothing more than a pretty little cluster with a bright double star, it contains an x-ray binary which is a “runaway” black hole. It is surmised that it formed near the galactic center and was vaulted into an eccentric orbit when the progenitor star exploded. Its kinetic energy is much like a neutron star or a millisecond pulsar, and it was the first black hole confirmed to be in motion.

Now head a little more than a degree east-southeast for NGC 6268 (Right Ascension: 17 : 02.4 – Declination: -39 : 44). At a rough magnitude of 9, this small open cluster can be easily observed in smaller scopes and resolved in larger ones. The cluster itself is somewhat lopsided, with more of its members concentrated on the western half of its borders. While it, too, might not seem particularly interesting, this young cluster is highly evolved and contains some magnetic, chemically peculiar stars and Be class, or metal-weak, members.

Friday, August 17 – Today in 1966 Pioneer 7 was launched. It was the second in a series of satellites sent to monitor the solar wind, and study cosmic rays, interplanetary space, and magnetic fields. If you’re out early, be sure to take a look for the close pairing of Mars and Saturn and Spica. If you’ve had the opportunity to view them over the last few days, you can see how quickly Mars has moved! Instead of being in a line, the trio now… well… triangulates!

Tonight it’s New Moon! Let’s return to previous study star Lambda Scorpii and hop three fingerwidths northeast… We’re re-hunting the “Butterfly!”

Easily seen in binoculars and tremendous in the telescope, this brilliant magnitude 4 open cluster was first discovered by Hodierna before 1654 and independently discovered by de Cheseaux as his object 1, before being cataloged by Messier as M6 (Right Ascension: 17 : 40.1 – Declination: -32 : 13). Containing around 80 stars, the light you see tonight left its home in space around the year 473 A.D. It is believed to be around 95 million years old and contains a single yellow supergiant – the variable BM Scorpii. While most of M6?s stars are hot, blue main sequence, the unique shape of this cluster gives it not only visual appeal, but wonderful color contrast as well!

Now let’s head towards more unusual open clusters – this time in Cygnus. Starting with Gamma Cygni, locate a loose cluster involving Gamma, Do (Dolidze) 43. Now shift two degrees southwest to pick up Do 42 as well. Don’t confuse Do 42 with nearby M29 though, for the two look very similar. For fans of the “Double Cluster” in Perseus, you’ll like the next pairing! Shift another half degree southwest along the body of Cygnus to pick out Do 40 and Do 41. This pretty pair can be placed in the same low power field. By moving another half degree due west, you’ll find highly populated Do 39 and that, too, is a double treat. The brighter clump of stars in the same low power field is IC 4996 (Right Ascension: 20 : 16.5 – Declination: +37 : 38).

Now for two bright open clusters. The first, Ruprecht 173 is about a degree northwest of Epsilon Cygni. You’ll truly appreciate this heavily populated star cluster! The next is as easy as identifying the constellation of Lyra. Just southeast of bright Vega is a wonderful double for binoculars, Delta 1 and 2 – the easternmost most two stars in the lyre. This bright pair is part of an open cluster known as Stephenson 1.

Saturday, August 18 – On this day in 1868, Norman Lockyer was very busy as he was the first to see helium absorption lines in the Sun’s spectrum. Tonight we’ll take a walk from helium rich Lambda Scorpii about three fingerwidths east-northeast to an even more prominent area of stars that was known to Ptolemy as far back as 130 AD.

Astronomers throughout the ages have spent time with this cluster: Hodierna as Ha II.2; Halley in 1678 as number 29, Derham in 1733 as number 16, De Cheseaux as number 10, Lacaille as II.14; Bode as 41; once for William Herschel and again for John as h 3710; Dreyer as NGC 6475… But we know it best as Messier Object 7 (Right Ascension: 17 : 53.9 – Declination: -34 : 49).

Set against the backdrop of the Milky Way, even the smallest of binoculars will enjoy this bright open cluster while telescopes can resolve its 80 members. Roughly 800 light-years away, it contains many different spectral types in various stages of evolution, giving the cluster an apparent age of about 260 million years. Full of binaries and close doubles, an extreme test of tonight’s lighting conditions would be to see if you can spot the 11th magnitude globular cluster NGC 6453 (Right Ascension: 17 : 50.9 – Declination: -34 : 36) to the northwest!

And for last, the densely populated open cluster M11 (Right Ascension: 18 : 51.1 – Declination: -06 : 16). The “Wild Duck” cluster soars about a fist’s width northeast of M16. Dominated by a single 8th magnitude star, this conically-shaped 3,000 member assembly of stardust easily resolves into innumerable stars with any significant amount of magnification. Through intermediate aperture, this 6000 light-year distant, 250 million year old cluster takes on a new form as several hundred 13th and 14th magnitude members begin to spill outside its V-shaped bounds! Discovered by Gottfried Kirch of Berlin observatory in 1681, the cluster was first noted as stellar by William Derham in the first third of the 18th century. Charles Messier added it to his catalog May 30, 1764.

Sunday, August 19 – Born today in 1646, let’s have a look at John Flamsteed. He was an English astronomer with a passion for what he did. Despite a rather difficult childhood and no formal education, he went on to become the First Observer at the Royal Observatory and his catalog of 3000 stars was perhaps the most accurate yet published. Flamsteed star numbers are still in use. Also born on this day was Orville Wright, in 1871, and in 1891, Milton Humason, a colleague of Edwin Hubble at Mts. Wilson and Palomar. The latter was instrumental in measuring the faint spectra of galaxies, which in turn provided evidence for the expansion of the Universe.

This would be a great time for us to have a look at one of the summer’s most curious galaxies – NGC 6822 (Right Ascension: 19 : 44.9 – Declination: -14 : 48). This study is a telescopic challenge even for skilled observers. Set your sights roughly 2 degrees northeast of easy double 54 Sagittarii, and have a look at this distant dwarf galaxy bound to our own Milky Way by invisible gravitational attraction…

Named after its discoverer (E. E. Barnard – 1884), “Barnard’s Galaxy” is a not-so-nearby member of our local galaxy group. Discovered with a 6? refractor, this 1.7 million light-year distant galaxy is not easily found, but can be seen with very dark sky conditions and at the lowest possible power. Due to large apparent size, and overall faintness (magnitude 9), low power is essential in larger telescopes to give a better sense of the galaxy’s frontier. Observers using large scopes will see faint regions of glowing gas (HII regions) and unresolved concentrations of bright stars. To distinguish them, try a nebula filter to enhance the HII and downplay the star fields. Barnard’s Galaxy appears like a very faint open cluster overlaid with a sheen of nebulosity, but the practiced eye using the above technique will clearly see that the “shine” behind the stars is extragalactic in nature.

Now look less than a degree north-northwest to turn up pale blue-green NGC 6818 (Right Ascension: 19 : 44.0 – Declination: -14 : 09) – the “Little Gem” planetary. Easily found in any size scope, this bright and condensed nebula reveals its annular nature in larger scopes but hints at it in scopes as small as 6?. Use a super wide field long-focus eyepiece to frame them both!

Until next week? Wishing you clear skies!

August 5, 2012December 23, 2015 by Tammy Plotner

Weekly SkyWatcher’s Forecast: August 6-12, 2012

Globular Cluster M15 from Hubble - Credit: ESA, Hubble, NASA

Greetings, fellow SkyWatchers! While you start your observing week out by watching the Mars Curiosity Landing, be sure to step outside and view the Aquarid meteor shower, too! It’s going to be a grand week for globular cluster studies and breezing along the Milky Way. Whenever you’re ready to learn some more history, mystery and just plain fun things about the night sky, then meet me in the back yard.

Monday, August 6 – Today in 2001 the Galileo spacecraft made its flyby of Jupiter’s moon – Io -sending back incredible images of the surface. For southern hemisphere observers, be on watch as the Iota Aquarid meteor shower peaks on this Universal date.

Tonight our studies of globular clusters continues as we look deeper into structure. As a rule, globular clusters normally contain a large number of variable stars, and most are usually the RR Lyrae type such as in earlier study M54. At one time they were known as “cluster variables,” with their number differing from one globular to another. Many globulars also contain vast numbers of white dwarfs. Some have neutron stars which are detected as pulsars, but out of all 151, only four have planetary nebulae in them.

Now, let us head toward the emerging constellation of Pegasus and the magnitude 6.5, class IV M15 (Right Ascension: 21 : 30.0 – Declination: +12 : 10). Easily located with even small binoculars about four degrees northwest of Enif, this magnificent globular cluster is a true delight in a telescope. Amongst the globulars, M15 ranks third in variable star population with 112 identified. As one of the densest of clusters, it is surprising that it is considered to be only class III. Its deeply concentrated core is easily apparent, and has begun the process of core collapse. The central core itself is very small compared to the cluster’s true size and almost half M15?s mass is contained within it. Although it has been studied by the Hubble, we still do not know if this density is caused by the cluster stars’ mutual gravity, or if it might disguise a supermassive object similar to those in galactic nuclei.

M15 was the first globular cluster in which a planetary nebula, known as Pease 1, could be identified. Larger aperture scopes can easily see it at high power. Surprisingly, M15 also is home to 9 known pulsars, which are neutron stars left behind from previous supernovae during the cluster’s evolution, and one of these is a double neutron star. While total resolution is impossible, a handful of bright stars can be picked out against that magnificent core region and wonderful chains and streams of members await your investigation tonight!

Tuesday, August 7 – On this date in 1959, Explorer 6 became the first satellite to transmit photographs of the Earth from its orbit.

Tonight, let’s return again to look at two giant globular clusters roughly equal in size, but not equal in class. To judge them fairly, you must use the same eyepiece. Start first by re-locating previous study M4. This is a class IX globular cluster. Notice the powder-like qualities. It might be heavily populated, but it is not dense. Now return to previous study M13. This is a class V globular cluster. Most telescopes will make out at least some resolution and a distinct core region. It is the level of condensation that determines the class. It is no different from judging magnitudes and simply takes practice.

Try your hand at M55 (Right Ascension:19 : 40.0 – Declination: -30 : 58) along the bottom of the Sagittarius “teapot” – it’s a class XI. Although it is a full magnitude brighter than class I M75, which we looked at earlier in the week, can you tell the difference in concentration? For those with GoTo systems, take a quick hop through Ophiuchus and look at the difference between NGC 6356 (class II) and NGC 6426 (class IX). If you want to try one that they can’t even classify? Look no further than M71 (Right Ascension: 19 : 53.8 – Declination: +18 : 47) in Sagitta. It’s all a wonderful game and the most fun comes from learning!

In the meantime, don’t forget all those other wonderful globular clusters such as 47 Tucanae, Omega Centauri, M56, M92, M28 and a host of others!

Wednesday, August 8 – Today in 2001, the Genesis Solar Particle Sample Return mission was launched. In September of 2004, it crash landed in the Utah desert with its precious payload. Although some of the specimens were contaminated, some did survive the mishap. So what is “star stuff?” Mostly highly charged particles generated from a star’s upper atmosphere and flowing out in a state of matter known as plasma…

Tonight let’s study one of the grandest of all solar winds as we seek out an area about three fingerwidths above the Sagittarius “teapot’s spout” as we have a look at magnificent M8 (Right Ascension: 18 : 03.8 – Declination: -24 : 23), the “Lagoon Nebula.”

Visible to the unaided eye as a hazy spot in the Milky Way, fantastic in binoculars, and an area truly worth study in any size scope, this 5200 light-year area of emission, reflection and dark nebulae has a rich history. Its involved star cluster – NGC 6530 – was first discovered by Flamsteed around 1680, and the nebula by Le Gentil in 1747. Cataloged by Lacaille as III.14 about 12 years before Messier listed it as number 8, its brightest region was recorded by John Herschel and the dark nebulae were discovered by Barnard.

Tremendous areas of starbirth are taking place in this region; while young, hot stars excite the gases in a are known as the “Hourglass,” around Herschel star 36 and 9 Sagittarius. Look closely around cluster NGC 6530 for Barnard dark nebulae B89 and B296 at the nebula’s southern edge. No matter how long you chose to swim in the “Lagoon” you will sure find more and more things to delight both the mind and the eye!

Thursday, August 9 – Today in 1976, the Luna 24 mission was launched on a return mission of its own – not to retrieve solar winds samples, but lunar soil! Remember this mission as we take a look at its landing site in the weeks ahead.

Tonight we’ll return to the nebula hunt as we head about a fingerwidth north and just slightly west of M8 for the “Trifid”…

M20 (Right Ascension: 18 : 02.3 – Declination: -23 : 02) was discovered by Messier on June 5, 1764, and much to his credit, he described it as a cluster of stars encased in nebulosity. This is truly a wonderful observation since the Trifid could not have been easy given his equipment. Some 20 years later William Herschel (although he usually avoided repeating Messier objects) found M20 of enough interest to assign separate designations to parts of this nebula – IV.41, V.10, V.11, V.12. The word “Trifid” was used to describe its beauty by John Herschel.

While M20 is a very tough call in binoculars, it is not impossible with good conditions to see the light of an area that left its home nearly a millennium ago. Even smaller scopes will pick up this round, hazy patch of both emission and reflection, but you will need aversion to see the dark nebula which divides it. This was cataloged by Barnard as B85. Larger telescopes will find the Trifid as one of the very few objects that actually appears much in the eyepiece as it does in photographs – with each lobe containing beautiful details, rifts and folds best seen at lower powers. Look for its cruciform star cluster and its fueling multiple system while you enjoy this triple treat tonight!

Friday, August 10 – Today in 1966 Lunar Orbiter 1 was successfully launched on its mission to survey the Moon. In the weeks ahead, we’ll take a look at what this mission sent back!

Tonight we’ll look at another star forming region as we head about a palm’s width north of the lid star (Lambda) in the Sagittarius teapot as we seek out “Omega”…

Easily viewed in binoculars of any size and outstanding in every telescope, the 5000 light-year distant Omega Nebula was first discovered by Philippe Loys de Cheseaux in 1745-46 and later (1764) cataloged by Messier as object 17. This beautiful emission nebula is the product of hot gases excited by the radiation of newly born stars. As part of a vast region of interstellar matter, many of its embedded stars don’t show in photographs, but reveal themselves beautifully to the eye of the telescope. As you look at its unique shape, you realize that many of these areas are obscured by dark dust, and this same dust is often illuminated by the stars themselves.

Often known as the “Swan,” M17 (Right Ascension: 18 : 20.8 – Declination: -16 : 11) will appear as a huge, glowing check mark or ghostly “2? in the sky – but power up if you use a larger telescope and look for a long, bright streak across its northern edge, with extensions to both the east and north. While the illuminating stars are truly hidden, you will see many glittering points in the structure itself and at least 35 of them are true members of this region spanning about 40 light-years that could contain up to 800 solar masses. It is awesome…

Saturday, August 11 – On this date in 1877, Asaph Hall of the U.S. Naval Observatory was very busy. This night would be the first time he would see Mars’ outer satellite Deimos! Six nights later, he observed Phobos, giving Mars its grand total of two moons.

Tonight after midnight is the peak of the Perseid meteor shower, and this year there’s not so much Moon to contend with! Now let’s sit back and talk about the Perseids while we watch…

The Perseids are undoubtedly the most famous of all meteor showers and never fail to provide an impressive display. Their activity appears in Chinese history as far back as 36 AD. In 1839, Eduard Heis was the first observer to give an hourly count, and discovered their maximum rate was around 160 per hour at that time. He, and other observers, continued their studies in subsequent years to find that this number varied.

Giovanni Schiaparelli was the first to relate the orbit of the Perseids to periodic comet Swift-Tuttle (1862 III). The fall rates have both risen and fallen over the years as the Perseid stream was studied more deeply, and many complex variations were discovered. There are actually four individual streams derived from the comet’s 120 year orbital period which peak on slightly different nights, but tonight through tomorrow morning at dawn is our accepted peak.

Meteors from this shower enter Earth’s atmosphere at a speed of 60 km/sec (134,000 miles per hour), from the general direction of the border between the constellations Perseus and Cassiopeia. While they can be seen anywhere in the sky, if you extend their paths backward, all the true members of the stream will point back to this region of the sky. For best success, position yourself so you are generally facing northeast and get comfortable. If you are clouded out, don’t worry. The Perseids will be around for a few more days yet, so continue to keep watch!

And speaking of watching… If you’re out late, be sure to watch for a Jupiter/Moon conjunction. What an inspiring bit of sky scenery to watch them rise together! For lucky viewers in the Indonesia area, this is an occultation event, so please be sure to check resources for times and locations in your area.

Sunday, August 12 – Did you mark your calendar to be up before dawn to view the Perseid meteor shower? Good!

Tonight while dark skies are on our side, we’ll fly with the “Eagle” as we hop another fingerwidth north of M17 and head for one of the most famous areas of starbirth – IC 4703.

While the open cluster NGC 6611 was first discovered by Cheseaux in 1745-6, it was Charles Messier who cataloged the object as M16 and he was the first to note the nebula IC 4703 (Right Ascension: 18 : 18.9 – Declination: -13 : 47), more commonly known as the “Eagle.” At 7000 light-years distant, this roughly 7th magnitude cluster and nebula can be spotted in binoculars, but at best it is a hint. As part of the same giant cloud of gas and dust as neighboring M17, the Eagle is also a place of starbirth illuminated by these hot, high energy stellar youngsters which are only about five and a half million years old.

In small to mid-sized telescopes, the cluster of around 20 brighter stars comes alive with a faint nebulosity that tends to be brighter in three areas. For larger telescopes, low power is essential. With good conditions, it is very possible to see areas of dark obscuration and the wonderful “notch” where the Pillars of Creation lie. Immortalized by the Hubble Space telescope, you won’t see them as grand or colorful as it did, but what a thrill to know they are there!

Until next week? Clear skies!

July 31, 2012December 23, 2015 by Tammy Plotner

Weekly SkyWatcher’s Forecast: July 30 – August 5, 2012

Greetings, fellow SkyWatchers! It’s big. It’s bright. There’s no escaping it. This week the Moon will be our major point of study, but don’t rule out some bright globular clusters and interesting stars! There’s plenty of history and science to explore, too. Whenever you’re ready, just meet me in the back yard…

Monday, July 30 – Today’s history celebrates the 2001 flyby of the Moon by the Wilkinson Microwave Anisotropy Probe (WMAP) on its way to Lagrange Point 2 to study the cosmic microwave background radiation.

Now that we’re back at Sinus Iridum on the lunar surface, we’ll hop across Mare Frigoris and northeast of the punctuation of Harpalus for a grand old crater – J. Herschel. Although it looks small because it is seen on the curve, this wonderful old walled plain named for John Herschel contains some very tiny details. Its southeastern rim forms the edge of Mare Frigoris and the small (24 km) Horrebow dots its southwest edge. The crater walls are so eroded with time that not much remains of the original structure. Look for many very small telescopic impact craters which dot J. Herschel’s uneven basin and exterior edges. Power up! If you can spot the small central crater C, you are resolving a feature only 12 kilometers wide from some 385,000 kilometers away! Formed in the Pre-Nectarian period, this walled plain could be as much as 4 billion years old…

Now, relax and enjoy the peak of the Capricornid meteor shower. Although it is hard for the casual observer to distinguish these meteors from the Delta Aquarids, no one minds. Again, face southeast and enjoy! The fall rate for this shower is around 10 to 35 per hour, but unlike the Aquarids, this stream produces those great “fireballs” known as bolides. Enjoy…

Tuesday, July 31 – Tonight on the Moon, look south of Mare Humorum is darker Paulus Epidemiarum eastward and paler Lacus Excellentiae westward. To their south you will see a complex cojoined series of craters we’ll take a closer look at – Hainzel and Mee. Hainzel was named for Tycho Brahe’s assistant and measures about 70 kilometers in length and sports several various interior wall structures. Power up and look. Hainzel’s once high walls were obliterated on the north-east by the strike that caused Hainzel C and to the north by impact which caused the formation of Hainzel A. To its basic south is eroded Mee – named for a Scottish astronomer. While Crater Mee doesn’t appear to be much more than simple scenery, it spans 172 kilometers and is far older than Hainzel. While you can spot it easily in binoculars, close telescope inspection shows how the crater is completely deformed by Hainzel. Its once high walls have collapsed to the northwest and its floor is destroyed. Can you spot small impact crater Mee E on the northern edge?

Now, let’s take the opportunity to look at two multiple star systems – Nu and Xi Scorpii.

Starting with Nu about a fingerwidth east and slightly north of bright Beta, we find a handsome duo of stars in a field of nebulosity that will challenge telescopic observers much the way that Epsilon Lyrae does. With any small telescope, the observer will easily see the widely separated A and C stars. Add just a little power and take your time… The C star has a D companion to the southwest! For larger telescopes, take a very close look at the primary star. Can you separate the B companion to the south?

Now let’s hop to Xi about four fingerwidths north of Beta.

Discovered by Sir William Herschel in 1782, this 80 light-year distant system poses a nice challenge for mid-sized scopes. The yellow-hued A and B pair share a very eccentric orbit about the same distance as Uranus is from our Sun. During the 2007 observing year they should be fairly well spaced, and the slightly fainter secondary should appear to the north. Look a good distance away for the 7th magnitude orange C component and south for yet another closely-matched double of 7th and 8th magnitude – the D and E stars.

For the larger scope, this multiple star system does display a little bit of color. Most will see the A and B components as yellow/white, the C star as slightly orange, and the D/E pair as slightly tinged with blue. Be sure to mark your observations for this is one of the finest!

Wednesday, August 1 – Today is the birthdate of Maria Mitchell. Born in 1818, Mitchell became the first woman to be elected as an astronomer to the American Academy of Arts and Sciences. She later rocketed to worldwide fame when she discovered a bright comet in 1847.

For larger telescopes, let’s try a challenging lunar study worthy of your observing skills. Due west of Hansteen you will find a small crater known as Sirsalis near the terminator. It will appear as a small, dark ellipse with a bright west wall along with its twin, Sirsalis B. The feature you will be looking for is the Sirsalis Rille – the longest lunar “wrinkle” presently known. Stretching northeast of Sirsalis and ex-tending 459 kilometers south to the bright rays of Byrgius, this major “crack” in the lunar surface shows several branchings – like a long dry river bed. Geologically forming in the Imbrian period, chances are the Sirsalis Rille is lunar graben. Thanks to Lunar Orbiter images, the evidence points to shifting tectonic plates as the source of this incredible feature.

Tonight, let’s continue our exploration of globular clusters. These gravitationally bound concentrations of stars contain anywhere from ten thousand to one million members and attain sizes of up to 200 light-years in diameter. At one time, these fantastic members of our galactic halo were believed to be round nebulae. Perhaps the very first to be discovered was M22 in by Abraham Ihle in 1665. This particular globular is easily seen in even small binoculars and can be located just slightly more than two degrees northeast of the “teapot’s lid,” Lambda Sagittarii.

Ranking third amongst the 151 known globular clusters in total light, M22 (Right Ascension: 18 : 36.4 – Declination: -23 : 54) is probably the nearest of these incredible systems to our Earth with an approximate distance of 9600 light-years, and it is also one of the nearest globulars to the galactic plane. Since it resides less than a degree from the ecliptic, it often shares the same eyepiece field with a planet. At magnitude 6, the class VII M22 will begin to show individual stars to even modest instruments and will burst into stunning resolution for larger aperture. About a degree west-northwest, mid-sized telescopes and larger binoculars will capture smaller 8th magnitude NGC 6642. At class V, this particular globular will show more concentration toward the core region than M22. Enjoy them both!

Thursday, August 2 – Tonight we’ll fly right by the Full Buck Moon as we continue our studies to have a look at Mu 1 and Mu 2 Scorpii about two fingerwidths north of Zeta.

Very close to the same magnitude and spectral type, the twin Mu stars are easy to separate visually and most definitely worth a look in telescopes or binoculars. They are considered an actual physical pair because they share the exact same distance and proper motion, but they are separated by less than one light-year.

Hanging out in space some 520 light-years away, western Mu 1 is a spectroscopic binary – the very first discovered to have double lines. This Beta Lyrae-type star has an orbiting companion that eclipses it around every day and a half, yet causes no significant visual drop in magnitude – even though the orbiting companion is only 10 million kilometers away from it! While that sounds like plenty of distance, when the two pass, their surfaces would nearly touch each other!

Friday, August 3 – Tonight let’s race ahead of the rising Moon as we continue our studies with one of the globulars nearest to the galactic center – M14 (Right Ascension: 17 : 37.6 – Declination: -03 : 15). Located about sixteen degrees (less than a handspan) south of Alpha Ophiuchi, this ninth magnitude, class VIII cluster can be spotted with larger binoculars, but will only be fully appreciated with the telescope.

When studied spectroscopically, globular clusters are found to be much lower in heavy element abundance than stars such as own Sun. These earlier generation stars (Population II) began their formation during the birth of our galaxy, making globular clusters the oldest of formations that we can study. In comparison, the disk stars have evolved many times, going through cycles of starbirth and supernovae, which in turn enrich the heavy element concentration in star forming clouds and may cause their collapse. Of course, as you may have guessed, M14 breaks the rules. It contains an unusually high number of variable stars – in excess of 70 – with many of them known to be the W Virginis type. In 1938, a nova appeared in M14, but it was undiscovered until 1964 when Amelia Wehlau of the University of Ontario was surveying the photographic plates taken by Helen Sawyer Hogg. The nova was revealed on eight of these plates taken on consecutive nights, and showed itself as a 16th magnitude star – and was believed to be at one time almost 5 times brighter than the cluster members. Unlike 80 years earlier with T Scorpii in M80, actual photographic evidence of the event existed. In 1991, the eyes of the Hubble were turned its way, but neither the suspect star nor traces of a nebulous remnant were discovered. Then six years later, a carbon star was discovered in M14.

To a small telescope, M14 will offer little to no resolution and will appear almost like an elliptical galaxy, lacking in any central condensation. Larger scopes will show hints of resolution, with a gradual fading towards the cluster’s slightly oblate edges. A true beauty!

Saturday, August 4 – As we explore globular clusters, we simply assume them all to be part of the Milky Way galaxy, but that might not always be the case. We know they are basically concentrated around the galactic center, but there may be four of them that actually belong to another galaxy. Tonight we’ll look at one such cluster being drawn into the Milky Way’s halo. Set your sights just about one and a half degrees west-southwest of Zeta Sagittarii for M54 (Right Ascension: 18 : 55.1 – Declination: -30 : 29).

At around magnitude 7.6, M54 is definitely bright enough to be spotted in binoculars, but its rich class III concentration is more notable in a telescope. Despite its brightness and deeply concentrated core, M54 isn’t exactly easy to resolve. At one time we thought it to be around 65,000 light-years distant, and rich in variables – with 82 known RR Lyrae types. We knew it was receding, but when the Sagittarius Dwarf Elliptical Galaxy was discovered in 1994, it was noted that M54 was receding at almost precisely the same speed! When more accurate distances were measured, we found M54 to coincide with the SagDEG distance of 80-90,000 light-years, and M54?s distance is now calculated to be 87,400 light-years. No wonder it’s hard to resolve – it’s outside our galaxy!

As we know, most globular clusters congregate around the galactic center in the Ophiuchus/Sagittarius region. Tonight let’s explore what creates a globular cluster’s form… We’ll start with the “head of the class,” M75 (Right Ascension: 20 : 06.1 – Declination: -21 : 55).

Orbiting the galactic center for billions of years, globular clusters endured a wide variety of disturbances. Their component stars escape when accelerated by mutual encounters and the tidal force of our own Milky Way pulls them apart when they are near periapsis, that is, closest to the galactic center. Even close encounters with other masses, such as other clusters and nebulae, can affect them! At the same time, their stellar members are also evolving and this loss of gas can contribute to mass loss and deflation of these magnificent clusters. Although this happens far less quickly than in open clusters, our observable globular friends may only be the survivors of a once larger population, whose stars have been spread throughout the halo. This destruction process is never-ending, and it is believed that globular clusters will cease to exist in about 10 billion years.

Although it will be later evening when M75 appears on the Sagittarius/Capricornus border, you will find the journey of about 8 degrees southwest of Beta Capricorni worth the wait. At magnitude 8, it can be glimpsed as a small round patch in binoculars, but a telescope is needed to see its true glory. Residing around 67,500 light-years from our solar system, M75 is one of the more remote of Messier’s globular clusters. Since it is so far from the galactic center – possibly 100,000 light-years distant – M75 has survived almost intact for billions of years to remain one of the few Class I globular clusters. Although resolution is possible in very large scopes, note that this globular cluster is one of the most concentrated in the sky, with only the outlying stars resolvable to most instruments.

Sunday, August 5 – Today we celebrate the birthday of Neil Armstrong, the first human to walk on the Moon. Congratulations! Also on this date in 1864, Giovanni Donati made the very first spectroscopic observations of a comet (Tempel, 1864 II). His observations of three absorption lines led to what we now know as the Swan bands, from a form of the carbon radical C2.

Our study continues tonight as we move away from the galactic center in search of a remote globular cluster that can be viewed by most telescopes. As we have learned, radial velocity measurements show us the majority of globulars are involved in highly eccentric elliptical orbits, which take them far outside the plane of the Milky Way. These orbits form a sort of spherical “halo” which tends to be more concentrated toward our galactic center. Reaching out several thousands of light-years, this halo is actually larger than the disk of our own galaxy. Since globular clusters aren’t involved in our galaxy’s disk rotation, they may possess very high relative velocities. Tonight let’s head toward the constellation of Aquila and look at one such globular – NGC 7006 (Right Ascension: 21 : 01.5 – Declination: +16 : 11).

Located about half a fist’s width east of Gamma Aquilae, NGC 7006 is speeding towards us at a velocity of around 345 kilometers per second. At 150,000 light-years from the center of our galaxy, this particular globular could very well be an extra-galactic object. At magnitude 11.5, it’s not for the faint of heart, but can be spotted in scopes as small as 150mm, and requires larger aperture to look like anything more than a suggestion. Given its tremendous distance from the galactic center, it’s not hard to realize this is a class I – although it is quite faint. Even the largest of amateur scopes will find it unresolvable!

Until next week? May all your skies by clear and steady…

Lead image caption: Crater J. Herschel – Credit: Damian Peach

July 22, 2012December 23, 2015 by Tammy Plotner

Weekly SkyWatcher’s Forecast: July 23-29, 2012

IC 4665 - Credit: Palomar Observatory, courtesy of Caltech

Greetings, fellow SkyWatchers! Are you ready for a week filled with alternative astronomical observing studies? If so, you’ll enjoy looking at some unusual stars and star clusters. If you want to keep things cool, then come along as we mine for lunar ice. Feeling a bit more lazy? Then kick back and enjoy the Delta Aquarid meteor shower or just step out after sunset and enjoy a splendid conjunction! It’s all here… Just head outside!

Monday, July 23 – Tonight we’ll launch our imaginations as we view the area around Mare Crisium and have a look at this month’s lunar challenge – Macrobius. You’ll find it just northwest of the Crisium shore. Spanning 64 kilometers in diameter, this Class I impact crater drops to a depth of nearly 3600 meters – about the same as many of our earthly mines. Its central peak rises up 1100 meters, and may be visible as a small speck inside the crater’s interior. Be sure to mark your lunar challenges and look for other features you may have missed before!

Now, relax and let’s talk until the Moon sets…

As we know most stars begin life in stellar nurseries and end life either alone or in very small groups as doubles or multiple stars. Tonight we can have a look at a group of young stars beginning their stellar evolution and end with an old solitary elder preparing to move on to an even “higher realm.” Open cluster IC 4665 (Right Ascension: 17 : 46.3 – Declination: +05 : 43) is easily detected with just about any optical aid about a finger-width north-northeast of Beta Ophiuchi. Discovered by Philippe Loys de Cheseaux in the mid-1700s, this 1400 light-year distant cluster consists of about 30 mixed magnitude stars all less than 40 million years of age. Despite its early discovery, the cluster did not achieve broad enough recognition for Dreyer to include it in the late 19th century New General Catalog and it was later added as a supplement to the NGC in the Index Catalog of 1908. Be sure to use low power to so see all of this large group.

About three finger-widths north-northeast of IC 4665 is a study that did make Dreyer’s catalogue – NGC 6572 (Right Ascension: 18 : 12.1 – Declination: +06 : 51). This 9th magnitude planetary is very small – but intense. Like the “Cat’s Eye” in Draco, and NGC 6210 in Hercules, this planetary can take a lot of magnification. Those with large scopes should look for a small, round, blue inner core encased is a faint shell. A challenge to find? You bet. Worth the work? Sometimes working for something makes it all the more fun!

Tuesday, July 24 – As our observing evening begins, be sure to look for one of the finest conjunctions of the year! Hovering around the waxing crescent Moon like bees drawn to a hive, you’ll find Mars to the upper right and Spica to the upper left (northwest and northeast respectively). To Spica’s upper right, you’ll find Saturn joining the show, too! This is a very “photogenic” opportunity…

With plenty of Moon to explore tonight, why don’t we try locating an area where many lunar exploration missions made their mark? Binoculars will easily reveal the fully disclosed areas of Mare Serenitatis and Mare Tranquillitatis, and it is where these two vast lava plains converge that we will set our sights. Telescopically, you will see a bright “peninsula” westward of where the two conjoin which extends toward the east. Just off that look for bright and small crater Pliny. It is near this rather inconspicuous feature that the remains Ranger 6 lie forever preserved where it crashed on February 2, 1964.

Unfortunately, technical errors occurred and it was never able to transmit lunar pictures. Not so Ranger 8! On a very successful mission to the same relative area, this time we received 7137 “postcards from the Moon” in the last 23 minutes before hard landing. On the “softer” side, Surveyor 5 also touched down near this area safely after two days of malfunctions on September 10, 1967. Incredibly enough, the tiny Surveyor 5 endured temperatures of up to 283 degrees F, but was able to spectrographically analyze the area’s soil… And by the way, it also managed to televise an incredible 18,006 frames of “home movies” from its distant lunar locale.

Wednesday, July 25 – Today in 1971, Apollo 15 was launched on its way towards the Moon, and we’ll continue our celebration of space exploration and walk on the Moon where the first man set foot. For SkyWatchers, the dark round area you see on the northeastern limb is Mare Crisium and the dark area below that is Mare Fecunditatis. Now look mid-way on the terminator for the dark area that is Mare Tranquillitatis. At its southwest edge, history was made.

In binoculars, trace along the terminator where the Caucasus Mountains stand – and then south for the Apennines and the Haemus Mountains. As you continue towards the center of the Moon, you will see where the shore of Mare Serenitatis curves east, and also the bright ring of Pliny. Continue south along the terminator until you spot the small, bright ring of Dionysius along the edge of Mare Tranquillitatis. Just to the southwest, you may be able to see the soft rings of Sabine and Ritter. It is near here where the base section of the Apollo 11 landing module – Eagle – lies forever enshrined in “magnificent desolation.”

For telescope users, the time is now to power up! See if you can spot small craters Armstrong, Aldrin and Collins just east. Even if you cannot, the Apollo 11 landing area is about the same distance as Sabine and Ritter are wide to the east-southeast. Even if you don’t have the opportunity to see it tonight, take the time during the next couple of days to point it out to your children, grandchildren, or even just a friend… The Moon is a spectacular world and we’ve been there!
Tonight let’s have a look with our eyes first at Delta Ophiuchi. Known as Yed Prior (“The Hand”), look for its optical double Epsilon to the southeast: Yed Posterior. Now have a look in binoculars or a telescope at absolute minimum power for another undiscovered gem…

Delta Ophiuchi is 170 light-years from us, while Epsilon is 108 – but look at the magnificent field they share. Stars of every spectral type are in an area of sky which could easily be covered by a small coin held at arm’s length. Enjoy this fantastic field – from the hot, blue youngsters to the old red giants!

Thursday, July 26 – Long before the Sun sets, look for the Moon to appear in the still-blue sky. As it darkens, watch for shadows on the surface. Have you ever wondered if there was any place on the lunar surface that hasn’t seen the sunlight? Then let’s go searching for one tonight…

Our first order of business will be to identify crater Albategnius. Directly in the center of the Moon is a dark floored area known as Sinus Medii. South of it will be two conspicuously large craters – Hipparchus to the north and ancient Albategnius to the south. Trace along the terminator toward the south until you have almost reached its point (cusp) and you will see a black oval. This normal looking crater with the brilliant west wall is equally ancient crater Curtius. Because of its high southern latitude, we shall never see the interior of this crater – and neither has the Sun! It is believed that the inner walls are quite steep and that Curtius’ interior has never been illuminated since its formation billions of years ago. Because it has remained dark, we can speculate that there may be “lunar ice” pocketed inside its many cracks and rilles that date back to the Moon’s formation!

Because our Moon has no atmosphere, the entire surface is exposed to the vacuum of space. When sunlit, the surface reaches up to 385 K, so any exposed “ice” would vaporize and be lost because the Moon’s gravity cannot hold it. The only way for “ice” to exist would be in a permanently shadowed area. Near Curtius is the Moon’s south pole, and the Clementine spacecraft’s imaging showed around 15,000 square kilometers in which such conditions could exist. So where did this “ice” come from? The lunar surface never ceases to be pelted by meteorites – most of which contain water ice. As we know, many craters were formed by just such impacts. Once hidden from the sunlight, this “ice” could remain for millions of years!

Friday, July 27 – Tonight let’s skip the Moon and take a look at an astounding system called 36 Ophiuchi, located about a thumb’s width southeast of Theta. Situated in space less than 20 light-years from Earth, even small telescopes can split this pair of 5th magnitude K type giants very similar to our own Sun, and larger telescopes can also pick up the C component as well. 36 Ophiuchi B is also known as system 544…because it has what could very likely be a planet in a habitable zone!

Now we’ll have a look at a beautifully contrasting pair of stars – Zeta 1 and 2 Scorpii. You’ll find them a little less than a handspan south-southeast of Antares and at the western corner of the J of the constellation’s shape.

Although the two Zetas aren’t a true physical pair, they are nonetheless interesting. The easternmost, orange sub-giant Zeta 2 appears far brighter for a reason… It’s much closer at only 155 light-years away. But, focus your attention on western Zeta 1. It’s a blue supergiant that’s around 5700 light-years away and shines with the light of 100,000 suns and exceeds even Rigel in sheer power! The colorful pair is easily visible as two separate stars to the unaided eye, but a real delight in binoculars or a low power telescope field. Check them out tonight!

Saturday, July 28 – Tonight let’s continue our studies of the lunar poles by returning to previous study crater Plato. North of Plato you will see a long horizontal area with a gray floor – Mare Frigoris. North of it you will note a double crater. This elongated diamond-shape is Goldschmidt and the crater which cuts across its western border is Anaxagoras. The lunar north pole isn’t far from Goldschmidt, and since Anaxagoras is just about one degree outside of the Moon’s theoretical “arctic circle” the lunar sun will never go high enough to clear the southernmost rim.

On March 5, 1998, NASA announced that Lunar Prospector’s neutron spectrometer data showed that water ice had been discovered at both lunar poles. The first results showed the ice was mixed in with lunar regolith (soil, rocks and dust), but long term data confirmed near pure pockets hidden beneath about 40 cm of surface material – with the results being strongest in the northern polar region. It is estimated there may be as much as 6 trillion kg (6.6 billion tons) of this valuable resource! If this still doesn’t get your motor running, then realize that without it, we could never establish a manned lunar base because of the tremendous expense involved in transporting our most basic human need – water.

The presence of lunar water could also mean a source of oxygen, another vital material we need to survive! And for returning home or voyaging further, these same deposits could provide hydrogen which could be used as rocket fuel. So as you view Anaxagoras tonight, realize that you may be viewing one of mankind’s future “homes” on a distant world!

Now grab a comfortable seat because the Delta Aquarid meteor shower reaches its peak tonight. It is not considered a prolific shower, and the average fall rate is about 25 per hour – but who wouldn’t want to take a chance on observing a meteor about every 4 to 5 minutes? These travelers are considered to be quite slow, with speeds around 24 kilometers per second and are known to leave yellow trails. One of the most endearing qualities of this annual shower is its broad stream of around 20 days before and 20 days after peak. This will allow it to continue for at least another week and overlap the beginning stages of the famous Perseids.

The Delta Aquarid stream is a complicated one, and a mystery not quite yet solved. It is possible that gravity split the stream from a single comet into two parts, and each may very well be a separate stream. One thing we know for certain is they will seem to emanate from the area around Capricornus and Aquarius, so you will have best luck facing southeast and getting away from city lights. Although the Moon will interfere, just relax and enjoy a warm summer night. It’s time to catch a “falling star!”

Sunday, July 29 – Tonight let’s take an entirely different view of the Moon as we do a little “mountain climbing!” The most outstanding feature on the Moon will be the emerging Copernicus, but since we’ve delved into the deepest areas of the lunar surface, why not climb to some of its peaks?

Using Copernicus as our guide, to the north and northwest of this ancient crater lie the Carpathian Mountains, ringing the southern edge of Mare Imbrium. As you can see, they begin well east of the terminator, but look into the shadow! Extending some 40 kilometers beyond the line of daylight, you will continue to see bright peaks – some of which reach 2072 meters high! When the area is fully revealed tomorrow, you will see the Carpathian Mountains eventually disappear into the lava flow that once formed them. Continuing onward to Plato, which sits on the northern shore of Imbrium, we will look for the singular peak of Pico. It is between Plato and Mons Pico that you will find the scattered peaks of the Teneriffe Mountains. It is possible that these are the remnants of much taller summits of a once stronger range, but only around 1890 meters still survives above the surface.

Time to power up! Lather, rinse and repeat until you know these by heart… To the west of the Teneriffes, and very near the terminator, you will see a narrow series of hills cutting through the region west-southwest of Plato. This is known as the Straight Range – Montes Recti – and some of its peaks reach up to 2072 meters. Although this doesn’t sound particularly impressive, that’s over twice as tall as the Vosges Mountains in central Europe and on the average very comparable to the Appalachian Mountains in the eastern United States. Not bad!

Now head about a palm’s width east of our previous study star – Zeta Scorpii – for lovely Theta. Named Sargas, this 1.8 magnitude star resides around 650 light-years distant in a very impressive field of stars for binoculars or a small telescope. While all of these are only optical companions, the field itself is worth a look – and worth remembering for the future.

About three fingerwidths north is true double Lambda Scorpii, also known as Shaula (The Sting). As the brightest known star in its class, 1.6 magnitude Lambda is a spectroscopic binary which is also a variable of the Beta Canis Majoris type, changing ever so slightly in little more than 5 hours. Although we can’t see the companion star, nearby is yet another that will make learning this starhop “marker” worth your time.

Until next week? Ask for the Moon, but keep on reaching for the stars!

July 15, 2012December 23, 2015 by Tammy Plotner

Weekly SkyWatcher’s Forecast: July 16-22, 2012

Messier 19 - Credit: Doug Williams, REU Program/NOAO/AURA/NSF

Greetings, fellow SkyWatchers! My satellite dish and internet connection has now returned from the land of Oz. While it was great to have a span of days where no electric meant no annoying lights, it also meant creative cooking excursions on the gas grill in 100 degree weather. Ah, well… the things we do for dark skies! This is New Moon week, so get out there and enjoy the Milky Way! Whenever you’re ready, meet me in the back yard…

Monday, July 16 – Today in 1850 at Harvard University, the first photograph of a star (other than the Sun) was made. The honors went to Vega! In 1994, an impact event was about to happen as nearly two dozen fragments of Comet Shoemaker-Levy 9 were speeding their way to the surface of Jupiter. The result was spectacular, and the visible features left behind on the planet’s atmosphere were the finest ever recorded.

Now let’s return again to the oblate and beautiful M19 and drop two fingerwidths south for another misshapen globular – M62 (Right Ascension: 17 : 01.2 – Declination: -30 : 07).

At magnitude 6, this 22,500 light-year distant Class IV cluster can be spotted in binoculars, but comes to wonderful life in the telescope. First discovered by Messier in 1771, Herschel was the first to resolve it and report on its deformation. Because it is so near to the galactic center, tidal forces have “crushed” it – much like M19. You will note when studying in the telescope that its core is very off center. Unlike M19, M62 has at least 89 known variable stars – 85 more than its neighbor – and the dense core may have undergone collapse. A large number of X-ray binaries have also been discovered within its structure, perhaps caused by the close proximity of stellar members. Enjoy it tonight!

Tuesday, July 17 – If you’re up to another challenge tonight, let’s go hunting Herschel I.44, also known as NGC 6401. You’ll find this 9.5 magnitude globular cluster around two fingerwidths northeast of Theta Ophiuchi and a little more than a degree due east of star 51 (Right Ascension: 17 : 38.6 – Declination: -23 : 55).

Discovered by William Herschel in 1784 and often classed as “uncertain,” today’s powerful telescopes have placed this halo object as a Class VIII and given it a rough distance from the galactic center of 8,800 light-years. Although neither William nor John could resolve this globular, and they listed it originally as a bright nebula, studies in 1977 revealed a nearby suspected planetary nebula named Peterson 1. Thirteen years later, further study revealed this to be a symbiotic star.

Symbiotic stars are a true rarity – not a singular star at all, but a binary system. A red giant dumps mass towards a white dwarf in the form of an accretion disc. When this reaches critical mass, it then causes a thermonuclear explosion resulting in a planetary nebula. While no evidence exists that this phenomenon is physically located within metal-rich NGC 6401, just being able to see it in the same field makes this journey both unique and exciting!

Wednesday, July 18 – On this day 27 years ago, India launched its first satellite (Rohini 1), and 31 years ago in the United States Gemini 10 launched carrying John Young and Michael Collins to space.

Now, let’s carry ourselves into space as we take a very unusual and beautiful journey to a bright and very colorful pair of stars known as Omicron 1 Cygni. Easily located about halfway between Alpha (Deneb) and Delta on the western side, this is a pure delight in binoculars or any size telescope. The striking gold color of 3.7 magnitude 31 Cygni (Omicron 1) is easily highlighted against the blue of same field companion, 5th magnitude 30 Cygni. Although this wide pairing is only an optical one, the K-type giant is a double star – an eclipsing variable around 150 times larger than or own Sun – and is surrounded by a gaseous corona more than double the size as the star itself. If you are using a scope, you can easy spot the blue tinted, 7th magnitude B star about one third the distance as between the two giants. Although our true pair are some 1.2 billion miles apart, they are oriented nearly edge-on from our point of view – allowing the smaller star to be totally eclipsed during each revolution. This total eclipse lasts for 63 days and happens about every 10.4 years, but don’t stay up too late… We’ve still got 7 years to wait!

Thursday, July 19 – Today in 1846, Edward Pickering was born. Although his name is not well known, he became a pioneer in the field of spectroscopy. Pickering was the Harvard College Observatory Director from 1876 to 1919, and it was during his time there that photography and astronomy began to merge. Known as the Harvard Plate Collection, these archived beginnings still remain a valuable source of data.

It’s New Moon, so why not have a look at something that would make Edward Pickering proud? He enthusiastically encouraged amateur astronomers, and founded the American Association of Variable Star Observers – so set your sights on RR Scorpius about two fingerwidths northeast of Eta and less than a fingerwidth southwest M62 (RA 16 56 37.84 Dec -30 34 48.2). This very red Mira type can reach as high as magnitude 5 and drop as low as 12 in about 280 days!

Tonight let’s just enjoy a little stargazing and revel in the beauty of our own galaxy’s spiral arm – the Milky Way. For those living in the city, you owe it to yourself to get away to a dark location to enjoy this veritable “river of stars” which spans out of the galactic center south and runs overhead. Almost directly behind you from the galactic anti-center stretches the Perseus arm, and the sight is a beautiful one. If skies are fine, you can easily see the dark dust rift where the arm separates and the billows of light of unresolved stars. It’s the most glorious sight of summer! While we have many days yet before the Aquarid meteor shower officially reaches its peak, you will be pleasantly surprised at this year’s high activity. They’ve been flying out of the night sky for almost two weeks now, and it would not surprise me if you saw ten or more per hour of these quick, bright visitors.

Friday, July 20 – Today was a busy day in astronomy history! In 1969, the world held its breath as the Apollo 11 lander touched down and Neil Armstrong and Edwin Aldrin became the first humans to touch the lunar surface. We celebrate our very humanity because even Armstrong was so moved that he messed up his lines! The famous words were meant to be “A small step for a man. A giant leap for mankind.” That’s nothing more than one small error for a man, and mankind’s success continued on July 20, 1976 when Viking 1 landed on Mars – sending back the first images ever taken from that planet’s surface.

If you’re out at sunset, be sure to look for the slimmest crescent Moon you can imagine… It will point your way to nearby Mercury! For lucky viewers “down under” this is an occultation event and will only be observable after sunset from southernmost regions of central Australia. Be sure to check the resources for websites like IOTA for specific times and locations.

The first assignment of the evening is a pair of interacting galaxies. 40 degrees northwest of Beta Canum Venaticorum is NGC 4490 (Right Ascension: 12 : 30.6 – Declination: +41 : 38) and smaller, fainter companion NGC 4485 (Right Ascension: 12 : 30.5 – Declination: +41 : 42). This pair, also known as Arp 269, are quite unusual in appearance to the larger scope. NGC 4490 is around magnitude 10 and shows a bright, irregular core region and a rather strange profile. Known as the “Cocoon” galaxy, it appears to almost reach toward its companion 3 degrees to the north. Progressively larger scopes under ideal conditions will be able to make out some faint mottling in the NGC 4490’s structure.

Now let’s honor southern skies by exploring the fantastic, NGC 3372 (Right Ascension: 10 : 43.8 – Declination: -59 : 52) – the Eta Carinae Nebula. As a giant, diffuse nebula with a visual brightness of magnitude 1, (wow!) it contains the most massive and luminous star in our Milky Way galaxy, Eta Carinae. It’s also home to a small cluster, Collinder 228, which is only one of 8 cataloged open clusters within the area of this huge star-forming region; the others are Bochum (Bo) 10, Trumpler (Tr) 14 (also cataloged as Cr 230), Tr 15 (= Cr 231), Cr 232, Tr 16 (= Cr 233), Cr 234, and Bo 11. Star Eta Carinae is involved in open cluster Trumpler 16. This fantastic nebula contains details which northerners can only dream about, such as the dark “Keyhole” and the “Homunkulus” around the giant star itself. A fantastic region for exploration with both telescopes and binoculars!

Saturday, July 21 – Today in 1961, Mercury 4 was launched, sending Gus Grissom into suborbital space on the second manned flight, and he returned safely in Liberty Bell 7.

Since the moonlight will now begin to interfere with our early evening globular cluster studies, let’s waive them for a while as we take a look at some of the region’s most beautiful stars. Tonight your goal is to locate Omicron Ophiuchi, about a fingerwidth northeast of Theta. At a distance of 360 light-years, this system is easily split by even small telescopes. The primary star is slightly dimmer than magnitude 5 and appears yellow to the eye. The secondary is near 7th magnitude and tends to be more orange in color. This wonderful star is part of many double star observing lists, so be sure to note it!

Tonight would be an ideal time to look at a brilliant open cluster about a fist width east of Epsilon Scorpii – M6 (Right Ascension: 17 : 40.1 – Declination: -32 : 13). On a moonless night, the 50 or so members of this 2000 light year distant, 100 million year old cluster can usually be seen unaided as a small fuzzy patch just above the Scorpion’s tail. Tonight we visit because the brighter skies will aid you in seeing the primary stars distinctive asterism. Using binoculars or telescope at lowest power, the outline of stars does truly resemble its namesake – the “Butterfly Cluster”. The M6 is much more than “just a pretty face” and we’ll be back to study under darker skies.

Sunday, July 22 – Tonight instead of lunar exploration, we will note the work of Friedrich Bessel, who was born on this day in 1784. Bessel was a German astronomer and mathematician whose functions, used in many areas of mathematical physics, still carry his name. But, you may put away your calculator, because Bessel was also the very first person to measure a star’s parallax. In 1837, he chose 61 Cygni and the result was no more than a third of an arc second. His work ended a debate that had stretched back two millennia to Aristotle’s time and the Greek’s theories about the distances to the stars.

Although you’ll need to use your finderscope with tonight’s brighter skies, you’ll easily locate 61 between Deneb (Alpha) and Zeta on the eastern side. Look for a small trio of stars and choose the westernmost. Not only is it famous because of Bessel’s work, but it is one of the most noteworthy of double stars for a small telescope. 61 Cygni is the fourth nearest star to Earth, with only Alpha Centauri, Sirius, and Epsilon Eridani closer. Just how close is it? Try right around 11 light-years.

Visually, the two components have a slightly orange tint, are less than a magnitude apart in brightness and have a nice separation of around 30 degrees to the south-southeast. Back in 1792, Piazzi first noticed 61’s abnormally large proper motion and dubbed it “The Flying Star.” At that time, it was only separated by around 10 degrees and the B star was to the northeast. It takes nearly 7 centuries for the pair to orbit each other, but there is another curiosity here. Orbiting the A star around every 4.8 years is an unseen body that is believed to be about 8 times larger than Jupiter. A star – or a planet? With a mass considerably smaller than any known star, chances are good that when you view 61 Cygni, you’re looking toward a distant world!

Until next week, dreams really do come true when you keep on reaching for the stars!

June 25, 2012December 23, 2015 by Tammy Plotner

Weekly SkyWatcher’s Forecast: June 25 – July 1, 2012

Crater Julius Caesar - Credit: Wes Higgins

Greetings, fellow SkyWatchers! What a great week to enjoy lunar features! We’ll celebrate many famous birthdays – including Charles Messier – and take on challenging double stars. If you’re in the mood to just kick back in a lawn chair and enjoy, then check out the June Draconid meteor shower. (sssssh… it may have been responsible for the Tunguska Blast!) Still more? Then keep an eye on the western horizon, because Mercury is about to become a “guest star” in the Beehive Cluster! When ever you’re ready, just meet me in the back yard…

Monday, June 25 – Today celebrates the birth of Hermann Oberth – who has often been considered the father of modern rocketry. Born in Transylvania in 1894, Oberth was a visionary who was convinced space travel would one day be possible. Inspired by the works of Jules Verne, Oberth studied rockets and wrote many books devoted to the possibility of achieving spaceflight. He was the first to conceive of rocket “stages” – allowing vehicles to expend their fuel and lose dead weight. But tonight you won’t need one of Oberth’s rockets to travel to the Moon, as take on another challenge as we look mid-way along the terminator at the west shore of Mare Tranquillitatis for crater Julius Caesar.

This is also a ruined crater, but it met its demise not through lava flow – but from a cataclysmic event. The crater is 88 kilometers long and 73 kilometers wide. Although its west wall still stands over 1200 meters high, look carefully at the east and south walls. At one time, something plowed its way across the lunar surface, breaking down Julius Caesar’s walls and leaving them to stand no higher than 600 meters at the tallest. While visiting the “Tranquil Sea”, look for the unusually shaped crater Hypatia. Can you spot its rima on the southern shore of Tranquillitatis? Perhaps the bright pockmark of Moltke on its north edge will help. Hypatia sits on the northern shore of a rugged area known as Sinus Asperitatis. Do you see Alfraganus on the terminator? Follow the terrain to Theophilus and look west for Ibyn-Rushd with crater Kant to the northwest and the beautiful peak of Mons Penck to its east.

Tuesday, June 26 – On this day in 1949, asteroid Icarus was discovered on a 48-inch Schmidt plate made nine months after that telescope went into operation, and just prior to the beginning of the multi-year National Geographic-Palomar Sky Survey. The asteroid was found to have a highly eccentric orbit and a perihelion distance of just 27 million kilometers, closer to the Sun than Mercury, giving it its unusual name. It was just 6.4 million kilometers from Earth at the time of discovery, and variations in its orbital parameters have been used to determine Mercury’s mass and test Einstein’s theory of general relativity.

But, today is even more special because it is the birthday of none other than Charles Messier, the famed French comet hunter. Born in 1730, Messier is best known for cataloging the 100 or so bright nebulae and star clusters that we now refer to as the Messier objects. The catalog was intended to keep both Messier and others from confusing these stationary objects with possible new comets.

] If you missed your chance last night to see the incredible Alpine Valley, it’s now fully disclosed in the sunlight. Viewable through binoculars as a thin, dark line, telescopic observers at highest powers will enjoy a wealth of details in this area, such as a crack running inside its boundaries. It’s a wonderful lunar observing challenge and a guide to our next lunar feature – Cassini and Cassini A. Where the valley joins the lunar Alps, follow the range south into Mare Imbrium. Along the way you will see the protruding bright peaks of Mons Blanc, Promontorium DeVille, and at the very end, Promontorium Agassiz ending in the smooth sands. Southeast of Agassiz you will spot Cassini. The major crater spans 57 kilometers and reaches a floor depth of 1240 meters. The challenge is to also spot the central crater A, which is only 17 kilometers wide, yet drops down another 2830 meters below the surface. This shallow crater holds another challenge within – Cassini A. But look carefully, can you spot the B crater on Cassini’s inner southwestern rim? Or the very small M crater just outside the northern edge?

For more advanced lunar observers, head a bit further south to the Haemus Mountains to look for the bright punctuation of a small crater on the southwest shore of Mare Serenitatis. Increase your magnification and look for a curious feature with an even more curious name… Rima Sulpicius Gallus. It is nothing more than a lunar wrinkle which accompanies the crater of the same name – a long-gone Roman counselor. Can you trace its 90 kilometer length?

Now see how many Messier objects that you can capture and wish Charles a happy birthday!

Wednesday, June 27 – Let’s begin our lunar studies tonight with a little “mountain climbing!” Using Copernicus as our guide, to the north and northwest of this ancient crater lie the Carpathian Mountains ringing the southern edge of Mare Imbrium. As you can see, they begin well east of the terminator, but look into the shadow! Extending some 40 kilometers beyond the line of daylight, you will continue to see bright peaks – some of which reach a height of 2072 meters. When the area is fully revealed tomorrow, you will see the Carpathian Mountains disappear into the lava flow that once formed them.

Let’s try looking just south of Sinus Medii and identifying these features: (1) Flammarion, (2) Herschel, (3) Ptolemaeus, (4) Alphonsus, (5) Davy, (6) Alpetragius, (7) Arzachel, (8) Thebit, (9) Purbach, (10) Lacaille, (11) Blanchinus, (12) Delaunay, (13) Faye, (14) Donati, (15) Airy, (16) Argelander, (17) Vogel, (18) Parrot, (19) Klein, (20) Albategnius, (21) Muller, (22) Halley, (23) Horrocks, (24) Hipparchus, (25) Sinus Medii

When skies are dark, it’s time to have a look at the 250 light-year distant silicon star Iota Librae. This is a real challenge for binoculars – but not because the components are so close. In Iota’s case, the near 5th magnitude primary simply overshadows its 9th magnitude companion! In 1782, Sir William Herschel measured them and determined them to be a true physical pair. Yet, in 1940 Librae A was determined to have an equal magnitude companion only .2 arc seconds away…. And the secondary was proved to have a companion of its own that echoes the primary. A four star system!

While you’re out, keep watch for a handful of meteors originating near the constellation of Corvus. The Corvid meteor shower is not well documented, but you might spot as many as ten per hour.

Thursday, June 28 – Tonight on the lunar surface, use crater Copernicus as a guide and look north-northwest to survey the Carpathian Mountains. The Carpathians ring the southern edge of Mare Imbrium beginning well east of the terminator. But let’s look on the dark side. Extending some 40 km beyond into the Moon’s own shadow, you can continue to see bright peaks – some reaching 2000 meters high! Tomorrow, when this area is fully revealed, you will see the Carpathians begin to disappear into the lava flow forming them. Continuing northward to Plato – on the northern shore of Mare Imbrium – re-identify the singular peak of Pico. Between Plato and Mons Pico you will find the many scattered peaks of the Teneriffe Mountains. It is possible that these are the remnants of much taller summits of a once precipitous range. Now the peaks rise less than 2000 meters above the surface.

Time to power up! West of the Teneriffes, and very near the terminator, you will see a narrow line of mountains, very similar in size to the Alpine Valley. This is known as the Straight Range or the Montes Recti. To binoculars or small scopes at low power, this isolated strip of mountains will appear as a white line drawn across the grey mare. It is believed this feature may be all that is left of a crater wall from the Imbrium impact. It runs for a distance of around 90 kilometers, and is approximately 15 kilometers wide. Some of its peaks reach as high as 2072 meters! Although this doesn’t sound particularly impressive, that’s over twice as tall as the Vosges Mountains in west-central Europe, and on the average very comparable to the Appalachian Mountains in the eastern United States.

When you’re finished with your lunar observations, tonight let’s try a challenging double star – Upsilon Librae. This beautiful red star is right at the limit for a small telescope, but quite worthy as the pair is a widely disparate double. Look for the 11.5 magnitude companion to the south in a very nice field of stars!

Friday, June 29 – Today we celebrate the birthday of George Ellery Hale, who was born in 1868. Hale was the founding father of the Mt. Wilson Observatory. Although he had no education beyond his baccalaureate in physics, he became the leading astronomer of his day. He invented the spectroheliograph, coined the word astrophysics, and founded the Astrophysical Journal and Yerkes Observatory. At the time, Mt. Wilson dominated the world of astronomy, confirming what galaxies were and verifying the expanding universe cosmology, making Mt. Wilson one of the most productive facilities ever built. When Hale went on to found Palomar Observatory, the 5-meter (200?) telescope was named for him and dedicated on June 3, 1948. It continues to be the largest telescope in the continental United States.

It’s time to head deeper toward the lunar south as we take a close look at the dark, heart-shaped region Palus Epidemiarum. Caught on its southern edge is the largely eroded Campanus with well defined Cichus to the east and Ramsden to the west. Power up in your telescope and look carefully at its smooth floors. If conditions are favorable, you will catch Rima Hesiodus cutting across its northern boundary and the crisscross pattern of Rima Ramsden in the western lobe. Can you make out a small, deep puncture mark to the northeast? It might be small, but it has a name – Marth.
Now let’s go deep south and have look at an area which once held something almost half a bright as tonight’s Moon and over four times brighter than Venus. Only one thing could light up the skies like that – a supernova. According to historical records from Europe, China, Egypt, Arabia and Japan, 1001 years ago the very first supernova event was noted. Appearing in the constellation of Lupus, it was at first believed to be a comet by the Egyptians, yet the Arabs saw it as an illuminating “star.”

Located less than a fingerwidth northeast of Beta Lupus (RA 15 02 48.40 Dec -41 54 42.0) and a half degree east of Kappa Centaurus, no visible trace is left of a once grand event that spanned five months of observation beginning in May, and lasting until it dropped below the horizon in September, 1006. It is believed all the force created from the event was converted to energy and very little mass remains. In the area, a 17th magnitude star shows a tiny gas ring and radio source 1459-41 remains our best candidate for pinpointing this incredible event.

Saturday, June 30 – We start our observing evening with the beautiful Moon as we return first to the ancient and graceful landmark crater Gassendi standing at the north edge of Mare Humorum. The mare itself is around the size of the state of Arkansas and is one of the oldest of the circular maria on the visible surface. As you view the bright ring of Gassendi, look for evidence of the massive impact which may have formed Humorum. It is believed the original crater may have been in excess of 462 kilometers in diameter, indenting the lunar surface almost twice over. Over time, similar smaller strikes formed the many craters around its edges and lava flow gradually gave the area the ridge- and rille-covered floor we see tonight. Its name is the “Sea of Moisture,” but look for its frozen waves in the long dry landscape.

Caught on the north-western rim of Mare Humorum, look for crater Mersenius. It is a typical Nectarian geological formation, spanning approximately 51 miles in diameter in all directions. Power up in a telescope to look for fine features such as steep slopes supporting newer impact crater Mersenius P and tiny interior craterlet chains. Can you spot white formations and crevices along its terraced walls? How about Rimae Mersenius? Further south you’ll spy tiny Liebig helping to support Mersenius D’s older structure, along with its own small set of mountains known as the Rupes Liebig. Continue to follow the edge of Mare Humorum around the wall known as Rimae Doppelmayer until you reach the shallow old crater Doppelmayer. As you can see, the whole floor fractured crater has been filled with lava flow from Mare Humorum’s formation, pointing to an age older than Humorum itself. Look for a shallow mountain peak in its center – there’s a very good chance this peak is actually higher than the crater walls. Did this crater begin to upwell as it filled? Or did it experience some volcanic activity of its own? Take a closer look at the floor if the lighting is right to spy a small lava dome and evidence of dark pyroclastic deposits – it’s a testament to what once was!

Still got the moonlight blues? Then try your hand at a super challenging double – Mu Librae. This pair is only a magnitude apart in brightness and right at the limit for a small telescope. Up the power slowly and look for the companion just to the southwest of the primary. Good luck and mark your observation because Mu’s blues are on many observing lists!

And out of the blue comes a meteor shower! Keep watch tonight for the June Draconids. The radiant for this shower will be near handle of Big Dipper – Ursa Major. The fall rate varies from 10 to 100 per hour, but tonight’s bright skies will toast most of the offspring of comet Pons-Winnecke. On a curious note, today in 1908 was when the great Tunguska impact happened in Siberia. A fragment of a comet, perhaps?

Sunday, July 1 – Today In 1917, the astronomers at Mt. Wilson were celebrating as the 100? primary mirror arrived. Up until that time, the 60? Hale telescope (donated by George Hale’s father) was the premier creation of St. Gobrain Glassworks – which was later commissioned to create the blank for the Hooker telescope. Thanks to the funds provided by John D. Hooker (and Carnegie), the dream was realized after years of hard work and ingenuity to create not only a building to properly house it – but the telescope workings as well. It saw “first light” five months later on November 1.
As anxious astronomers waited for this groundbreaking moment, the scope was aimed at Jupiter but the image was horrible – to their dismay, workmen had left the dome open and the Sun had heated the massive mirror! Try as they might to rest until it had cooled – no astronomer slept. Fearful of the worst, sometime around three in the morning they returned again long after Jupiter had set. Pointing the massive scope towards a star, they achieved a perfect image!

If you’re looking for a perfect image, then look no further than the western horizon tonight at twilight. Why? Because Mercury is going to be a “guest star” in the Beehive Cluster! Be sure to at least get out your binoculars and look at the speedy little inner planet as it cruises about a degree or so to the western edge of M44.

Tonight we’ll return again to our landmark lunar feature – crater Grimaldi – and begin our journey north…

As you move north of Grimaldi on a crater hop, the next feature you will en-counter is the walled plain of Hevelius. With a diameter of about 64 miles, this round area doesn’t have a height we can really measure because of its lunar position, but we can see that it does have some relatively steep walls around its edges. Hevelius was formed in the Nectarian geological period and if you look closely you’ll see that it has a small central peak, a fine rimae and many craterlet chains, too. Can you spot large interior Crater Hevelius A with just binoculars? How about companion crater Cavalerius which is part of its northern border?

While you’re out, take the time to look at lowly Theta Lupi about a fistwidth south-southwest of the mighty Antares. While this rather ordinary looking 4th magnitude star appears to be nothing special – there’s a lesson to be learned here. So often in our quest to look at the bright and incredible – the distant and the impressive – we often forget about the beauty of a single star. When you take the time to seek the path less traveled, you just might find more than you expected. Hiding behind a veil of the “ordinary” lies a trio of three spectral types and three magnitudes in a diamond-dust field. An undiscovered gem…

Until next week? Ask for the Moon, but keep on reaching for the stars!

June 25, 2012December 23, 2015 by Nancy Atkinson

Mysterious Noctilucent Clouds as Seen from the International Space Station

Mysterious “night shining” or noctilucent clouds are beautiful to behold, and this stunning image offers an unusual view of these clouds as seen by astronauts on board the International Space Station. Also called polar mesospheric clouds, these clouds are puzzling scientists with their recent dramatic changes. They used to be considered rare, but now the clouds are growing brighter, are seen more frequently, are visible at lower and lower latitudes than ever before, and sometimes they are even appearing during the day.

The astronauts were also able to take a time-lapse sequence of these clouds on June 5, 2012, as seen below. According to NASA, it is first such sequence of images of the phenomena taken from orbit.

The sequence in this video was taken while the ISS was passing over western Asia. By focusing on the limb of the Earth at night with the Sun illuminating it, the crew was able to capture some movement to these mysterious clouds.

There is quite a bit of debate for the cause of noctilucent clouds. Dust from meteors, global warming, and rocket exhaust have all been tagged as contributors, but the latest research suggests that changes in atmospheric gas composition or temperature has caused the clouds to become brighter over time.

Noctilucent clouds are usually seen during the summertime, appearing at sunset. They are thin, wavy ice clouds that form at very high altitudes (between 76 to 85 kilometers (47 to 53 miles) above Earth’s surface and reflect sunlight long after the Sun has dropped below the horizon. They appear in both the Northern and Southern Hemisphere and appear as delicate, shining wispy clouds against the dark sky.

The top image from the ISS was taken on June 13, 2012, as the space station passed over the Tibetan Plateau. At the same time, polar mesospheric clouds were also visible to aircraft flying over Canada. In addition to the noctilucent/polar mesospheric clouds trending across the center of the image, lower layers of the atmosphere are also illuminated. The lowest layer of the atmosphere visible in this image—the stratosphere—is indicated by dim orange and red tones near the horizon.

Lead image caption: Noctilucent or Polar Mesospheric clouds captured by the crew of the ISS on June 13, 2012. Credit: NASA

Source: NASA Earth Observatory

June 22, 2012December 23, 2015 by Nancy Atkinson

Early “Elemental” Galaxy Found 12.4 Billion Light Years Away

This is definitely a story about a galaxy long ago and far away. An international team of researchers using the Atacama Large Millimeter/submillimeter Array (ALMA) has observed a “submillimeter galaxy” located about 12.4 billion light-years away. Their observations have revealed that the elemental composition of this galaxy in the early universe, at only 1.3 billion years after the Big Bang, was already close to the current elemental composition of the Universe. This means that intense star formation was taking place at that early point in the Universe’s history.

A submillimeter galaxy is a type of galaxy which has intense star formation activity and is covered by large amounts of dust. Since dust blocks observations in visible light, using ALMA’s millimeter wavelength capabilities can penetrate and see though dust clouds. In addition, ALMA also has extraordinary sensitivity, which is capable of catching even extremely faint radio signals. This is one of the most distant galaxies ALMA has ever observed.

The team was able to examine the chemical composition of the galaxy, called LESS J0332, and detected an emission line that contained nitrogen. To do this, they compared the brightness ratio of the observed emission lines from nitrogen and carbon with theoretical calculations. Their results showed that the elemental composition of LESS J0332, especially the abundance of nitrogen, is significantly different from that of the Universe immediately after the Big Bang – which consisted of almost only hydrogen and helium — but was much more similar to that of our Sun today, where a variety of elements exist abundantly.

It took 12.4 billion years for the emission lines from LESS J0332 to reach us, which means that the team was able to observe the galaxy located in the young universe at 1.3 billion years after the Big Bang.

“Submillimeter galaxies are thought to be relatively massive galaxies in the growth phase. Our research, revealing that LESS J0332 already has an elemental composition similar to the sun, shows us that the chemical evolution of these massive galaxies occurred rapidly made in the early universe, that is to say, in the early universe active star formation occurred for a short period of time,” said Tohru Nagao from Kyoto University, co-author of the paper.

The observations were made with ALMA, even though construction is not yet completed; only 18 antennas were used in this observation, while ALMA will be equipped with 66 antennas when completed.

This research was published in the “Letters” section of the journal, “Astronomy & Astrophysics.”

Lead image caption: Artist impression of the submillimeter galaxy LESS J0332 observed the ALMA at the 5000-meter altitude plateau. [Credit: NAOJ]

Source: ALMA

June 18, 2012December 23, 2015 by Tammy Plotner

Weekly SkyWatcher’s Forecast: June 18-24, 2012

NGC 3981 - Credit: Palomar Observatory, Courtesy of Caltech

Greetings, fellow SkyWatchers! Let’s begin the week with some awesome galactic studies and enjoy a meteor shower during Summer Solstice! We’ll be studying variable stars, the planet Mars, Saturn, the Moon and Mercury, too! There’s always a bit of astronomy history and some unusual things to learn about. When you’re ready, just meet me in the back yard…

Monday, June 18 – With dark skies on our side, we’ll spend the next few days concentrating on a very specific region of the night sky. Legend tells us the constellation of Crater is the cup of the gods – cup befitting the god of the skies, Apollo. Who holds this cup, dressed in black? It’s the Raven, Corvus. The tale is a sad one – a story of a creature sent to fetch water for his master, only to tarry too long waiting on a fig to ripen. When he realized his mistake, the sorry Raven returned to Apollo with his cup and brought along the serpent Hydra in his claws as well. Angry, Apollo tossed them into the sky for all eternity and it is in the south they stay until this day.

For the next few days, it will be our pleasure to study the Cup and the Raven. The galaxies I have chosen are done particularly for those of us who still star hop. I will start with a “marker” star that should be easily visible unaided on a night capable of supporting this kind of study. The field stars are quite recognizable in the finder and this is an area that takes some work. Because these galaxies approach magnitude 13, they are best suited to the larger telescope.

Now, let’s go between map and sky and identify both Zeta and Eta Crater and form a triangle. Our mark is directly south of Eta the same distance as between the two stars. At low power, the 12.7 magnitude NGC 3981 (Right Ascension: 11 : 56.1 – Declination: -19 : 54) sits inside a stretched triangle of stars. Upon magnification, an elongated, near edge-on spiral structure with a bright nucleus appears. Patience and aversion makes this “stand up” galaxy appear to have a vague fading at the frontiers with faint extensions. A moment of clarity is all it takes to see tiny star caught at the edge.

Tuesday, June 19 – New Moon! Tonight’s first study object, 12.7 magnitude NGC 3956 (Right Ascension: 11 : 54.0 – Declination: -20 : 34) is about a degree due south of NGC 3981. When first viewed, it appears as edge-on structure at low power. Upon study it takes on the form of a highly inclined spiral. A beautiful multiple star, and a difficult double star also resides with the NGC 3956 – appearing almost to triangulate with it. Aversion brings up a very bright core region which over the course of time and study appears to extend away from the center, giving this very sweet galaxy more structure than can be called from it with one observation.

Our next target is a little more than two degrees further south of our last study. The 12.8 magnitude NGC 3955 (Right Ascension: 11 : 54.0 – Declination: -23 : 10) is a very even, elongated spiral structure requiring a minimum of aversion once the mind and eye “see” its position. Not particularly an impressive galaxy, the NGC 3955 does, however, have a star caught at the edge as well. After several viewings, the best structure I can pull from this one is a slight concentration toward the core.

Now we’ll study an interacting pair and all that is required is that you find 31 Corvii, an unaided eye star west of Gamma and Epsilon Corvii. Now we’re ready to nudge the scope about one degree north. The 11th magnitude NGC 4038/39 (Right Ascension: 12 : 01.9 – Declination: -18 : 52) is a tight, but superior pair of interacting galaxies. Often referred to as either the “Ringtail” or the “Antenna”, this pair deeply captured the public’s imagination when photographed by the Hubble. (Unfortunately, we don’t have the Hubble, but what we have is set of optics and the patience to find them.) At low power the pair presents two very stellar core regions surrounded by a curiously shaped nebulosity. Now, drop the power on it and practice patience – because it’s worth it! When that perfect moment of clarity arrives, we have crackling structure. Unusual, clumpy, odd arms appear at strong aversion. Behind all this is a galactic “sheen” that hints at all the beauty seen in the Hubble photographs. It’s a tight little fellow, but worth every moment it takes to find it.

Return to 31 Corvii and head one half degree northwest to discover 11.6 magnitude NGC 4027 (Right Ascension: 11 : 59.5 – Declination: -19 : 16). Relatively large, and faint at low power, this one also deserves both magnification and attention. Why? Because it rocks! It has a wonderful coma shape with a single, unmistakable bold arm. The bright nucleus seems to almost curl along with this arm shape and during aversion a single stellar point appears at its tip. This one is a real treat!

Wednesday, June 20 – Today marks the official date of 2012 Summer Solstice!

With no Moon to contend with in the predawn hours, we welcome the “shooting stars” as we pass through another portion of the Ophiuchid meteor stream. The radiant for this pass will be nearer Sagittarius and the fall rate varies from 8 to 20, but it can sometimes produce unexpectedly more.

Tonight let’s look to the sky again and fixate on Eta Crater – our study lay one half degree southeast. The 12.8 magnitude NGC 4033 (Right Ascension: 12 : 00.6 – Declination: -17 : 51) is a tough call even for a large scope. Appearing elliptical at low power, it does take on some stretch at magnification. It is smallish, even and quite unremarkable. It requires good aversion and a bit of patience to find. Good luck!

The last of our studies resides by a star, one degree west of Beta Corvii. In order to “see” anything even remotely called structure in NGC 4462 (Right Ascension: 12 : 29.3 – Declination: -23 : 10), this one is a high power only galaxy that is best when the accompanying star is kept out of the field as much as possible. It holds a definite stellar nucleus and a concentration that pulls away from it making it almost appear barred. On an exceptional night with a large scope, wide aversion and moments of clarity show what may be three to four glints inside the structure. Ultra tiny pinholes in another universe? Or perhaps an unimaginably huge, bright globular clusters? While attention is focused on trying to draw out these points, you’ll notice this galaxy’s structure much more clearly. Another true beauty and fitting way to end this particular study field!

Thursday, June 21 – Keep an eye out for the exiting planet Mars! It’s been on the move and has now crossed the border of Virgo and returned to Leo. Have you noticed it quickly changing in both apparent brightness and size? It won’t be long until it’s gone! And speaking of planets on the move, have you spotted Mercury yet? You can find the swift little planet low on the western horizon just after sunset. Look for it just to the south of Castor and Pollux!

For challenging larger telescope studies, return to eastern edge of Mare Crisium and Promontorium Agarum to identify shallow crater Condorcet to its east. Look along the shore of the mare for a mountain to the south known as Mons Usov. Just to its north Luna 24 landed and directly to its west are the remains of Luna 15. We’ll study more about them in the future. Can you spot the tiny dark well of crater Fahrenheit nearby? Continue with your telescope north of Mare Crisium for even more challenging features such as northeast limb studies Mare Smythii and Mare Marginis. Between them you will see the long oval crater Jansky – bordered by Jansky A at the very outer edge.

While you’re out tonight, take a look at the skies for a circlet of seven stars that reside about halfway between orange Arcturus and brilliant blue/white Vega. This quiet constellation is named Corona Borealis – or the “Northern Crown.” Just northwest of its brightest star is a huge concentration of over 400 galaxies that reside over a billion light-years away from us. This area is so small from our point of view that we could cover it with our thumbnail held at arm’s length!

For variable star fans, let’s explore Corona Borealis and focus our attention on S – located just west of Theta – the westernmost star in the constellation’s arc formation. At magnitude 5.3, this long-term variable takes almost a year to go through its changes; usually far outshining the 7th magnitude star to its northeast – but will drop to a barely visible magnitude 14 at minimum. Compare it to the eclipsing binary U Coronae Borealis about a degree northwest. In slightly over three days this Algol-type will range by a full magnitude as its companions draw together.

Friday, June 22 – Today celebrates the founding of the Royal Greenwich Observatory in 1675. That’s 332 years of astronomy! Also on this date in history, in 1978, James Christy of the US Naval Observatory in Flagstaff Arizona discovered Pluto’s satellite Charon.

If you’d like to practice some unaided eye astronomy, then look no further than the western skyline as the Sun sets. At twilight you’ll first notice the very slender crescent Moon – but don’t delay your observations as you can spot Mercury to the west! The inner planet will set very fast, so you’ll need an open horizon. But that’s not all… the speedy little dude is lined up perfectly with Castor and Pollux! With the foursome nearly “in a row” this will make a very cool apparition to remind friends and family to watch for!

Now, grab your favorite optics for a selenographic treat tonight return to the area just north of Mare Crisium area to observe spectacular crater Cleomides. This two million year old crater is separated from Crisium by some 60 kilometers of mountainous terrain. Telescopically, Cleomides is a true delight at high power. To Cleomides’ east, begin by identifying Delmotte, and to the northwest, Trailes and Debes. About twice Clemoides’ width northwest, you will see a sharply well-defined Class I crater Geminus. Named for the Greek astronomer and mathematician Geminos, this 86 kilometer wide crater shows a smooth floor and displays a long, low dune across its middle.

When you’re finished, point your binoculars or telescopes back towards Corona Borealis and about three fingerwidths northwest of Alpha for variable star R (Ra 15. 48.6 Dec +28 09). This star is a total enigma. Discovered in 1795, most of the time R carries a magnitude near 6, but can drop to magnitude 14 in a matter of weeks – only to unexpectedly brighten again! It is believed that R emits a carbon cloud which blocks its light. When studied at minima, the light curve resembles a “reverse nova,” and has a peculiar spectrum. It is very possible this ancient Population II star has used all of its hydrogen fuel and is now fusing helium to carbon. It’s so odd that science can’t even directly determine its distance!

Saturday, June 23 – If you missed yesterday’s apparition of Mercury, then try again tonight. While the small planet might be dim, just look for the brighter pairing of Castor and Pollux above the western horizon at twilight. Can’t find it? Then try this. When you look at this famous pair of stars, judge the distance between the two. Now, apply that same distance and angle to the left (southern) star, Pollux, and you’ve found Mercury! Need more? Then check out the Moon and you’ll see Regulus is about a fistwidth to the east/southeast and Mars is a little more than two handspans to the southeast. Still more? Then continue on from Mars southeast about about another two handspans and you’ll see the pairing of Spica and Saturn!

Using your telescope tonight on the Moon will call up previous study craters, Atlas and Hercules to the lunar north. If you walk along the terminator to the due west of Atlas and Hercules, you’ll see the punctuation of 40 kilometer wide Burg just emerging from the shadows. While it doesn’t appear to be a grand crater just yet, it has a redeeming feature – it’s deep – real deep. If Burg were filled with water here on Earth, it would require a deep submergence vehicle like ALVIN to reach its 3680 meter floor! This class II crater stands nearly alone on an expanse of lunarscape known as Lacus Mortis. If the terminator has advanced enough at your time of viewing, you may be able to see this walled-plain’s western boundary peeking out of the shadows.

While we’re out, let’s have a look at Delta Serpens. To the eye and binoculars, 4th magnitude Delta is a widely separated visual double star… But power up in the telescope to have a look at a wonderfully difficult binary. Divided by no more than 4 arc seconds, 210 light-year distant Delta and its 5th magnitude companion could be as old as 800 million years and on the verge of becoming evolved giants. Separated by about 9 times the distance of Pluto from our Sun, the white primary is a Delta Scuti-type variable which changes subtly in less than four hours. Although it takes the pair 3200 years to orbit each other, you’ll find Delta Serpens to be an excellent challenge for your optics.

Sunday, June 24 – On this day in 1881, Sir William Huggins made the first photographic spectrum of a comet (1881 III) and discovered cyanogen (CN) emission at violet wavelengths. Unfortunately, his discovery caused public panic around 29 years later when Earth passed through the tail of Halley’s Comet. What a shame the public didn’t realize that cyanogens are also released organically! More than fearing what is in a comet’s tail, they should have been thinking about what might happen should a comet strike. Tonight look at the wasted Southern Highland area of the Moon with new eyes… Many of these craters you see were caused by impacts – some as large as the nucleus of Halley itself.

Now let’s pick up a binocular curiosity located on the northeast shore of Mare Serenitatis. Re-identify the bright ring of Posidonius, which contains several equally bright points both around and within it – and look at Mare Crisium and get a feel for its size. A little more than one Crisium’s length west of Posidonius you’ll meet Aristotle and Eudoxus. Drop a similar length south and you will be at the tiny, bright crater Linne on the expanse of Mare Serenitatis. So what’s so cool about this little white dot? With only binoculars you are resolving a crater that is one mile wide, in a seven mile wide patch of bright ejecta – from close to 400,000 kilometers away! While you were there, did you notice how much Proclus has changed tonight? It is now a bright circle and beginning to show bright lunar rays…

Before we head for deep sky, be sure to at least take a look at Saturn and Mars. Right now the Ring King has reached its greatest westward position and will begin its tour back to the east. Now, check out Mars’ position to the west and measure with your hands roughly how far apart they are. At this point they are separated by about two handspans. Check again in a few weeks to see planetary motion displayed right before your eyes!

Now let’s turn binoculars or telescopes towards magnitude 2.7 Alpha Librae – the second brightest star in the celestial “Scales.” Its proper name is Zuben El Genubi, and even as “Star Wars” as that sounds, the “Southern Claw” is actually quite close to home at a distance of only 65 light-years. No matter what size optics you are using, you’ll easily see Alpha’s 5th magnitude companion widely spaced and sharing the same proper motion. Alpha itself is a spectroscopic binary which was verified during an occultation event, and its inseparable companion is only a half magnitude dimmer according to the light curves. Enjoy this easy pair tonight!

Until next week? Ask for the Moon… But keep on reaching for the stars!

June 15, 2012December 23, 2015 by Nancy Atkinson

Astronomers View Asteroid 2012 LZ1’s Bright Flyby

As reported, asteroid 2012 LZ1 came about 5.3 million km (3.3 million miles) from planet Earth on its closest approach on June 14th, 2012. The fairly big and unusually bright space rock is about 502 meters (1,650 feet) wide. The Remanzacco Observatory crew of Nick Howes, Ernesto Guido & Giovanni Sostero captured this imagery of the pass.

Ian Musgrave in Australia also took some imagery of the pass:

Asteroid 2012 LZ1 imaged by Ian Musgrave with the iTelescope T16. Click for larger view of the image.

According to a little research by David Dickinson (@Astroguyz on Twitter) by looking at ESA’s NEODYS-2 website, this rock won’t be back in Earth’s vicinity again until June 12th, 2053, and will be about 3 times as distant.

There was no danger this asteroid would impact Earth at the distance it passed, and it appears it won’t be a problem in the future. But it has been classified as a Potentially Hazardous Asteroid. PHAs are asteroids larger than approximately 100 meters that can come closer to our planet than 0.05 AU (7.4 million km, 4.65 million miles). None of the known PHAs is on a collision course with our planet, although, as the Remanzacco team pointed out, astronomers are finding new ones all the time.

See the Minor Planet Center for more details on this object.