Posted on by Fraser Cain

M55 — Or a Swarm of Angry Bees?

M55. Image credit: ESO
M55. Image credit: ESO

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Globular clusters are my absolute favorite telescope targets. Okay, Saturn, and then globular clusters. And that’s why I’ve absolutely fallen in love with this amazing picture from the European Southern Observatory of the globular cluster M55, located in the constellation Sagittarius. In fact, it’s my new desktop wallpaper (it should be yours too, click here and download the screensize that fits your monitor)

Globular clusters contain vast numbers of stars clumped together in a tight area. In the case of M55, there are about 100,000 stars grouped up within a sphere only 100 light-years across. Astronomers know that globular clusters are old, almost as old as the Universe itself. In fact, for the longest time, astronomers calculated the age of globular clusters to be older than the estimated age of the Universe. Of course, there was an incorrect measurement there, and astronomers eventually aligned the age of globular clusters and the Universe.

M55 is thought to have formed 12.3 billion years ago, when the Universe was less than 3 billion years old. The most ancient stars in the cluster burned out a long time ago, detonating as supernovae. We’re now left with the cooler, lower mass stars, which slowly wink out one-by-one becoming white dwarfs as they proceed through the full stellar life cycle. Our own Sun is only halfway through its own lifespan, before it runs out of hydrogen fuel and becomes a white dwarf.

There are at least 160 globular clusters scattered across the Milky Way, grouped up more towards our galaxy’s core. We can only see some of the clusters because the bright core of the Milky Way obscures our view to objects on the other side. But other galaxies, with their own globular clusters show us what our own galaxy probably looks like from afar.

M55 is part of the Messier catalog; a collection of objects that looked comet-like to the eyes of Charles Messier, a French astronomer working in the 18th century. Messier recorded a list of more than 100 objects which could be confused as comets: galaxies, clusters, and nebulae.

Want to see M55 on your own? You’ll need at least a pair of 50 mm binoculars or a small telescope, some nice dark skies, and a clear view to the constellation Sagittarius. Sagittarius looks exactly like a teapot in the sky, hovering above the southern horizon in summer. The further south you go, the higher Sagittarius will be in the sky.

But you’ll never see a view or take an image as detailed as this photo. That’s because it was captured with the ESO’s 4.1-metre (13.4 foot) Visible and Infrared Survey Telescope for Astronomy (VISTA) at ESO’s Paranal Observatory in northern Chile.

Original Source: ESO News Release

Posted on by Jason Major

We Are In This Universe; The Universe Is In Us

The latest installment of the excellent Symphony of Science series is out, and like every one of them it’s a fun, inspirational and educational trip through the cosmos with voiceovers by leading astronomers and physicists. These are great, and if you haven’t seen the others be sure to check them out on creator John Boswell’s YouTube channel here.

Read more on the Symphony of Science website.

“We are part of this universe
We are in this universe
The universe is in us
Yes, the universe is in us”

– Neil deGrasse Tyson

Posted on by Jon Voisey

Searching for Exoplanet Oceans More Challenging Than First Thought

Earth Observation of sun-glinted ocean and clouds
Earth Observation of sun-glinted ocean and clouds. Credit: NASA

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As astronomers continue to discover more exoplanets, the focus has slowly shifted from what sizes such planets are, to what they’re made of. First attempts have been made at determining atmospheric composition but one of the most desirable finds wouldn’t be the gasses in the atmosphere, but the detection of liquid water which is a key ingredient for the formation of life as we know it. While this is a monumental challenge, various methods have been proposed, but a new study suggests that these methods may be overly optimistic.

One of the most promising methods was proposed in 2008 and considered the reflective properties of water oceans. In particular when the angle between a light source (a parent star) and an observer is small, the light is not reflected well and ends up being scattered into the ocean. However, if the angle is large, the light is reflected. This effect can be easily seen during sunset over the ocean when the angle is nearly 180° and the ocean waves are tipped with bright reflections and is known as specular reflection. This effect is illustrated in orbit around our own planet above and such effects were used on Saturn’s moon Titan to reveal the presence of lakes.

Translating this to exoplanets, this would imply that planets with oceans should reflect more light during their crescent phases than their gibbous phase. Thus, they proposed, we might detect oceans on extrasolar planets by the “glint” on their oceans. Even better, light reflecting off a smoother surface like water tends to be more polarized than it might be otherwise.

The first criticisms of this hypothesis came in 2010 when other astronomers pointed out that similar effects may be produced on planets with a thick cloud layer could mimic this glinting effect. Thus, the method would likely be invalid unless astronomers were able to accurately model the atmosphere to take its contribution into consideration.

The new paper brings additional challenges by further considering the way material would likely be distributed. Specifically, it is quite likely that planets in the habitable zones without oceans may have polar ice caps (like Mars) which are more reflective all around. Since the polar regions make up a larger percentage of the illuminated body in the crescent phase than during the gibbous, this would naturally lead to a relative diminishing in overall reflectivity and could give false positives for a glint.

This would be especially true for planets that are more oblique (are “tilted”). In this case, the poles receive more sunlight which makes the reflections from any ice caps even more pronounced and mask the effect further. The authors of the new study conclude that this as well as the other difficulties “severely limits the utility of specular reflection for detecting oceans on exoplanets.”

Posted on by Tammy Plotner

Weekly SkyWatcher’s Forecast – May 7-13, 2012

NGC 2903 - Credit: Palomar Observatory Courtesy of Caltech

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Greetings, fellow SkyWatchers! With the Moon rising a bit later each night, it’s time to begin the galaxy hunt once again! Keep an eye on Venus as it heads quickly towards the Sun and becomes more slender and brilliant each night. Don’t forget about Mars and Saturn, too… They are both well-placed for early evening observing. When you’re ready, meet me in the back yard…

Monday, May 7 – Tonight begin your observations just as soon as it is dark and look for an object that can be viewed unaided from a dark location and is splendid in binoculars. Just northeast of Beta Leonis you’ll see a hazy patch of stars known as Melotte 111. Often called the “Queen’s Hair,” this five degree span of 5th to 10th magnitude stars is wonderfully rich and colorful. As legend has it, Queen Berenice offered her beautiful long tresses to the gods for the King’s safe return from battle. Touched by her love, the gods took Berenice’s sacrifice and immortalized it in the stars.

The cluster is best in binoculars because of its sheer size, but you’ll find other things of interest there as well. Residing about 260 light-years away, this collection is one of the nearest of all star clusters, including the Pleiades and the Ursa Major moving group. Although Melotte 111 is more than 400 million years old, it contains no giant stars, but its brightest members have just begun their evolution. Unlike the Pleiades, The Queen’s Hair has no red dwarfs and a low stellar concentration which leads astronomers to believe it is slowly dispersing. Like many clusters, it contains double stars – most of which are spectroscopic. For binoculars, it is possible to split star 17, but it will require very steady hands.

Tuesday, May 8 – Have you checked out Saturn lately? The Ring King is still hanging out with Spica. Before we leave Leo to softly exit west, there is another galaxy that is so worth your time to visit that even binoculars can spot it. You’ll need to identify slightly fainter Lambda to the southwest of Epsilon and head south about one fingerwidth for NGC 2903 (Right Ascension: 9 : 32.2 – Declination: +21 : 30).

This awesome oblique spiral galaxy was discovered by William Herschel in 1784. At a little brighter than magnitude 9, it is easily in range of most binoculars. It is odd that Messier missed this one considering both its brightness and the fact that three of the comets he discovered passed by it! Perhaps it was cloudy when Messier was looking, but we can thank Herschel for cataloging NGC 2903 as H I 56.

While small optics will only perceive this 25 million light-year distant beauty as a misty oval with a slightly brighter core region, larger aperture will light this baby up. Soft suggestions of its spiral arms and concentrations will begin to appear. One such knot is star cloud NGC 2905 – a detail in a distant galaxy so prominent that it received its own New General Catalog designation. NGC 2903 is roughly the same size as our own Milky Way, and includes a central bar – yet the nucleus of our distant cousin has “hot spots” that were studied by the Hubble Telescope and extensively by the Arecibo telescope. While our own galactic halo is filled with ancient globular clusters, this galaxy sports brand new ones!

Be sure to mark your notes with your observations, because many different organizations consider this to be on their “Best of” lists.

While your still in a Leo frame of mind, be sure to have a look at Mars before you go… Tonight the red planet has moved more than 1 AU away from Earth!

Wednesday, May 9 – While our destination tonight isn’t quite so romantic, I think you’ll enjoy getting a “Blackeye.” You’ll find it located just one degree east-northeast of 35 Coma Berenices and it is most often called M64 (Right Ascension: 12 : 56.7 – Declination: +21 : 41).

Originally discovered by Bode about a year before Messier cataloged it, M64 is about 25 million light-years away and holds the distinction of being one of the more massive and luminous of spiral galaxies. It has a very unusual structure and is classified as an Sa spiral in some catalogs and an Sb in others. Overall, its arms are very smooth and show no real resolution to any scope – yet its bright nucleus has a incredible dark dustlane that consumes the north and eastern regions around its core – giving rises to its nickname – the Blackeye Galaxy.

In binoculars, this 8.5 magnitude galaxy can be perceived as a small oval with a slightly brighter center. Small telescope users will pick out the nucleus more easily, but will require both magnification and careful attention to dark adaptation to catch the dustlane. In larger telescopes, the structure is easily apparent and you may catch the outer wisps of arms on nights of exceptional seeing.

No matter what you use to view it, this is one compact and bright little galaxy!

Thursday, May 10 – Tonight let’s use our binoculars and telescopes and return to a globular cluster we’ve studied before- M3 (Right Ascension: 13 : 42.2 – Declination: +28 : 23). You will discover this ancient beauty about halfway between the pair of Arcturus and Cor Caroli – just east of Beta Comae. There’s a reason we’re returning! Discovered by Charles Messier on May 3, 1764, this ball of approximately a half million stars is one of the oldest formations in our galaxy. At around 40,000 light-years away, this awesome globular cluster spans about 220 light-years and is believed to be as much as 10 billion years old. Now, get a grasp on this concept, because our own Sun is less than half that age!

Let’s further our understanding of distance and how it affects what we see. As you know, light travels at an amazing speed of about 300,000 kilometers per second. To get a feel for this, how many seconds are there in a minute? An hour? A week? A month? How about a year? Ah, you’re beginning to see the light! For every second – 300,000 kilometers. M3 is 40,000 years away traveling at the speed of light. In terms of kilometers – that’s far more zeros than most of us can possibly understand – yet we can still see this great globular cluster. Now let’s locate M53 near Alpha Comae. Aim your binoculars or telescopes there and you will find M53 Right Ascension: 13 : 12.9 – Declination: +18 : 10) about a degree northeast.

This very rich, magnitude 8.7 globular cluster is almost identical to M3, but look at what a difference an additional 25,000 light-years can make to how we see it! Binoculars can pick up a small round fuzzy, while larger telescopes will enjoy the compact bright core as well as resolution at the cluster’s outer edges. As a bonus for scopes, look one degree to the southeast for the peculiar round cluster NGC 5053. Classed as a very loose globular, this magnitude 10.5 grouping is one of the least luminous objects of its type due to its small stellar population and the wide separation between members – yet its distance is almost the same as that of M3.

Friday, May 11 – Tonight, start by locating 5th magnitude 6 Comae Berenices about three fingerwidths east of Beta Leonis. Remember this star! We are going on a galaxy hop to a Mechain discovery that is less than a degree west, and its designation is M98 (Right Ascension: 12 : 13.8 – Declination: +14 : 54).

At magnitude 10, this beautiful galaxy is a telescope-only challenge and a bit on the difficult side for small aperture. Long considered to be part of the Virgo Cluster, M98 is approaching us at a different rate than other cluster members, giving rise to speculation that it may simply be in the line of sight. Quite simply put, it has a blue shift instead of red! But considering that all these galaxies (and far fainter ones than we can see), are in close proximity leads some researchers to believe it is a true member by virtue of the extreme tidal forces which must exist in the area – pushing it toward us at this point in time, rather than away.

In a small telescope, M98 will appear like a slim line with a slightly brighter nucleus – a characteristic of an edge-on galaxy. To large aperture, its galactic disk is hazy and contains patchiness in structure. These are regions of newly forming stars and vast regions of dust – yet the nucleus remains a prominent feature. It’s a very large galaxy, so be sure to use a minimum of magnification and plenty of aversion to make out small details in this fine Messier object!

Saturday, May 12 – Tonight we’ll return once again to 6 Coma Berenices and head no more than a half degree southwest for another awesome galaxy – M99 (Right Ascension: 12 : 18.8 – Declination: +14 : 25).

Discovered by Pierre Mechain on the same night as he found M98, this is one of the largest and brightest of the spiral galaxies in the Virgo Cluster. Recognized second after M51 for its structure, Lord Rosse proclaimed it to be “a bright spiral with a star above.” It is an Sc class, and unlike its similarly-structured neighbors – it rotates clockwise.

Receding from us at 2324 kilometers per second, its speedy retreat through the galaxy fields and close pass to approaching M98 may be the reason that it is asymmetrical – with a wide arm extending to the southwest. Three documented supernovae have been recorded in M99 – in 1967, 1972 and 1986.

Possible in large binoculars with excellent conditions, this roughly 9th magnitude object is low surface brightness and requires clean skies to see details. For a small telescope, you will see this one as fairly large, round, wispy, and with a bright nucleus. But, unleash aperture if you have it! For large scopes, the spiral pattern is very prominent and the western arm shows well. Areas within the structure are patchworked with bright knots of stars and thin dustlanes which surround the concentrated core region. During steady seeing, a bright, pinpoint stellar nucleus will come out of hiding. A worthy study!

Sunday, May 13 – Tonight we’ll return again to 6 Comae and our hunt will be for the last of the three galaxies discovered by Mechain on that same wonderful night in 1781. You’ll find it just a fingerwidth northeast of 6. Its name is M100 (Right Ascension: 12 : 22.9 – Declination: +15 : 49).
M100 is one of the brightest member galaxies of the Virgo Cluster of galaxies – and its design is much like our own galaxy. From our point of view, we see M100 “face on,” and even Lord Rosse in 1850 was able to detect a spiral form from a mere 60,000 light years away. Thanks to its proximity to other galactic members, it has two grand arms in which recently-formed, young, hot, massive stars reside. Regardless of what seems to be perfect form, the nucleus shows that younger stars have formed more to the south side than the north. Perhaps an interaction with its dwarf neighbors?

Achievable in binoculars as a soft round glow, and about the same in a small telescope, extensive photography has shown M100 to be far larger than previously believed – with a substantial portion of its mass contained in faint outer regions. The Hubble Telescope discovered over 20 Cepheids variables and one nova contained inside our spiral friend and was more able to accurately determine its distance at 6 million light-years. In addition, NASA’s Ultraviolet Imaging Telescope has shown starburst and formation activity at the edges of M100’s inner spiral arms.

Larger telescopes will see this galaxy’s intense core region as slightly elliptical and sometimes reveal patchiness in the structure. With good sky conditions, even smaller scopes can reveal a spiral pattern, and this improves significantly with aperture. Be sure to look carefully because five supernovae events have been observed in this hot galaxy – one as recently as February 2006!

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

Posted on by Nancy Atkinson

Beautiful, Glowing Dust in Orion

This image of the region surrounding the reflection nebula Messier 78, just to the north of Orion’s belt, shows clouds of cosmic dust threaded through the nebula like a string of pearls. Credit: ESO/APEX (MPIfR/ESO/OSO)/T. Stanke et al./Igor Chekalin/Digitized Sky Survey 2

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On Earth, dust can be pretty mundane. But in space, dust can be beautiful, especially when the dust reflects starlight – and even more so when we have the chance to see the reflections in different wavelengths. Here in NGC 2068, also called Messier 78, this dazzling submillimetre-wavelength view from the Atacama Pathfinder Experiment (APEX) telescope Dust shows the glow of interstellar dust grains, pointing the way to where new stars are being formed.
This reflection nebula lies just to the north of Orion’s Belt. When seen in visible light glimmers in a pale blue glow of starlight, but much of the light is blocked by the dust. In this image, the APEX observations are overlaid on the visible-light image in orange. APEX’s view reveals the gentle glow of dense cold clumps of dust, some of which are even colder than -250 C.

A visible light image from ESO of the reflection nebula Messier 78. Credit: ESO and Igor Chekalin

Compare the new image with this earlier, visible light image of M78.

One filament seen by APEX appears in visible light as a dark lane of dust cutting across Messier 78. This tells us that the dense dust lies in front of the reflection nebula, blocking its bluish light. Another prominent region of glowing dust seen by APEX overlaps with the visible light from Messier 78 at its lower edge. The lack of a corresponding dark dust lane in the visible light image tells us that this dense region of dust must lie behind the reflection nebula.

Observations of the gas in these clouds reveal gas flowing at high velocity out of some of the dense clumps. These outflows are ejected from young stars while the star is still forming from the surrounding cloud. Their presence is therefore evidence that these clumps are actively forming stars.

At the top of the image is another reflection nebula, NGC 2071. While the lower regions in this image contain only low-mass young stars, NGC 2071 contains a more massive young star with an estimated mass five times that of the Sun, located in the brightest peak seen in the APEX observations.

This chart shows the location of Messier 78 in the famous constellation of Orion (The Hunter). This map shows most of the stars visible to the unaided eye under good conditions, and Messier 78 itself is highlighted with a red circle on the image. This reflection nebula is quite bright and can be seen well in moderate-sized amateur telescopes. Credit: ESO, IAU and Sky & Telescope

Source: ESO

Posted on by Nancy Atkinson

Hundreds of Rogue Stars Found Just Outside the Milky Way

astronomers have identified nearly 700 rogue stars that appear to have been ejected from the Milky Way galaxy. When these stars received the powerful kick that knocked them out of the galaxy, they were small, yellow stars like the sun. But in the multi-million-year journey they evolved into red giant stars. Credit: Michael Smelzer, Vanderbilt University

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It’s not quite like being kicked off a reality TV show, but some stars can get kicked out from their home galaxy. These stars – called various names like rogue, runaway or hypervelocity stars – were predicted to exist for quite some time, and finally just in the past couple of years a few of them have actually been discovered. But now a group of nearly 700 rogue stars have been found on the outskirts of the Milky Way. The astronomers who found them argue they are hypervelocity stars that have been ejected from the center of the galaxy.

“These stars really stand out. They are red giant stars with high metallicity which gives them an unusual color,” said Kelly Holley-Bockelmann from Vanderbilt University, who conducted the study with graduate student Lauren Palladino.

They found these stars analyzing the millions of stars cataloged in the Sloan Digital Sky Survey.

“We figured that these rogue stars must be there, outside the galaxy, but no one had ever looked for them. So we decided to give it a try,” said Holley-Bockelmann, who is studying the behavior of the black hole at the center of the Milky Way galaxy.

Runaway stars are kicked into motion either through a supernova explosion of a companion star, through gravitational interactions with other stars in a cluster, or through encounters with a black hole. One scenario could involve a binary pair of stars that get caught in the black hole’s grip, and as one of the stars spirals in towards the black hole, its companion is flung outward at a tremendous velocity.

This is the scenario the researchers focused on, and so they looked for red giant stars just outside the Milky Way.

Red giant stars are the end stage in the evolution of small, yellow stars like the Sun. So, the stars in this new red giant rogues category should have been small stars like the Sun when they got ejected. As they traveled outward, they continued to age until they reached the red giant stage. Even traveling at hypervelocities, it would take a star about 10 million years to travel from the central hub to the spiral’s edge, 50,000 light years away.

“Studying these rogue stars can provide us with new insights into the history and evolution of our home galaxy,” said Holley-Bockelmann

There are a few methods for discovering runaway rogue stars. The first is to examine stars individually and analyze their motion in the plane of the sky (proper motion) along with their motion towards or away from us (radial velocity) to determine if a given star has sufficient velocity to escape. The second is to look at the effects some stars have on the local environment. Since young clusters contain large amounts of gas and dust, stars plowing through it will create bow shocks, similar to those a boat makes in the ocean.

A fast-moving star, Alpha Camelopardalis, creates a stunning bow shock in this image from WISE. Credit: NASA/JPL-Caltech/WISE Team

The team from Vanderbilt selected these stars based on their location in intergalactic space between the Milky Way and the nearby Andromeda galaxy and by their peculiar red coloration.

The researchers’ next step is to determine if any of their candidates are unusually red brown dwarfs instead of red giants. Because brown dwarfs produce a lot less light than red giants, they would have to be much closer to appear equally bright.

Read the team’s paper.

Source: Vanderbilt University

Posted on by Tammy Plotner

Weekly SkyWatcher’s Forecast: April 30-May 6, 2012

Large Magellanic Cloud - Image Courtesy of NASA

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Greetings, fellow SkyWatchers! Are you ready for another week filled with bright planets, a meteor shower, challenging lunar features, interesting stars and astronomy history? Then you have come to the right place! Bring along your telescopes and binoculars and meet me in the backyard…

Monday, April 30 – Karl Frederich Gauss was born on this day in 1777. Known as the “Prince of Mathematics,” Gauss contributed to the field of astronomy in many ways – from computing asteroid orbits to inventing the heliotrope. Out of Gauss’ many endeavors, he is most recognized for his work in magnetism. We understand the term “gauss” as a magnetic unit – a refrigerator magnet carries about 100 gauss while an average sunspot might go up to 4000. On the most extreme ends of the magnetic scale, the Earth produces about 0.5 gauss at its poles, while a magnetar can produce as much as 10 to the 15th power in gauss units!

While we cannot directly observe a magnetar, those living in the Southern Hemisphere can view a region of the sky where magnetars are known to exist – the Large Magellanic Cloud – or you can use the projection method to view a sunspot! If you have a proper solar filter, magnetism distorts sunspots as they near the limb – called the “Wilson Effect”

Tuesday, May 1 – On this day in 1949 Gerard Kuiper discovered Nereid, a satellite of Neptune. If you’re game, you can find Neptune – usually hanging around in Capricornus – about an hour before dawn. While it can be seen in binoculars as a bluish “star,” it takes around a 6″ telescope and some magnification to resolve its disc. Today’s imaging technology can even reveal its moons!

While you’re out this morning, keep an eye on the sky for the peak of the Phi Bootid meteor shower, whose radiant is near the constellation of Hercules. While the best time to view a meteor shower is around 2:00 a.m. local time, you will have best success watching for these meteors when the Moon is as far west as possible. The average fall rate is about 6 per hour.

Our lunar mission for tonight is to move south, past the crater rings of Ptolemaeus, Alphonsus, Arzachel, and Purbach, until we end up at the spectacular crater Walter.

Named for Dutch astronomer Bernhard Walter, this 132- by 140-kilometer-wide lunar feature offers up amazing details at high power. It is worthwhile to take the time to study the differing levels, which drop to a maximum of 4,130 meters below the surface. Multiple interior strikes abound, but the most fascinating of all is the wall crater Nonius. Spanning 70 kilometers, Nonius would also appear to have a double strike of its own—one that’s 2,990 meters deep!

Wednesday, May 2 – On the lunar surface, we can enjoy a strange, thin feature. If you used last night’s map, you’re well acquainted with this area! Look toward the lunar south where you will note the prominent rings of craters Ptolemaeus, Alphonsus, Arzachel, Purbach, and Walter descending from north to south. Just west of them, you’ll see the emerging Mare Nubium. Between Purbach and Walter you will see the small, bright ring of Thebit with a crater caught on its edge. Look further west and you will see a long, thin, dark feature cutting across the mare. Its name? Rupes Recta – better known as The Straight Wall, or sometimes Rima Birt. It is one of the steepest known lunar slopes rising around 366 meters from the surface at a 41 degree angle.

Be sure to mark your lunar challenge notes and we’ll visit this feature again!

Another great target for a bright night is Delta Corvi. 125 light-years away, it displays a yellowish color primary and slightly blue secondary that’s an easily split star in any telescope, and a nice visual double with Eta in binoculars. Use low power and see if you can frame this bright grouping of stars in the same eyepiece field.

Before you put the telescope away for the evening, be sure to visit with Mars. If you’ve been keeping track, the red planet is slowly moving away from us and dimming even more. Tonight it should have reached an apparent -0.0 magnitude. Compare it to other nearby stars and gauge its brightness for yourself. How has its apparent position against the background stars changed over the weeks? Have you noted features like Syrtis Major or Amazonis Planitia? How have the polar caps changed?

Thursday, May 3 – Tonight we’ll use what we learned previously to locate another unusual feature – Montes Recti or the “Straight Range.” You’ll find this curiosity tucked between Plato and Sinus Iridum on the north shore of Mare Imbrium.

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. The Straight Range 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 western Europe, and on the average very comparable to the Appalachian Mountains in the eastern United States.

Friday, May 4 – Tonight you are on your own without a map. Lunar features are easy when you become acquainted with them! Return to the Moon and explore with binoculars or telescopes the area to the south around another easy and delightful lunar feature you should recognize, the crater Gassendi. At around 110 kilometers in diameter and 2010 meters deep, this ancient crater contains a triple mountain peak in its center. As one of the most “perfect circles” on the Moon, the south wall of Gassendi has been eroded by lava flows over a 48 kilometer expanse and offers a great amount of detail to telescopic observers on its ridge- and rille-covered floor. For those observing with binoculars? Gassendi’s bright ring stands on the north shore of Mare Humorum…an area about the size of the state of Arkansas!

Northeast of Regulus by about a fistwidth is 2.61 magnitude Gamma Leonis – also known as Algieba. This is one of the finest double stars in the sky, but a little difficult at low power since the pair is both bright and close. Separated by about twice the diameter of our own solar system, this 90 light-year distant pair is slowly widening.

Another two fingerwidths north is 3.44 magnitude Zeta Leonis – also named Aldhafera. Located about 130 light-years away, this excellent star has an optical companion which is viewable in binoculars – 35 Leonis. Remember this pair, because it will lead you to galaxies later!

Saturday, May 5 – In 1961 Alan Shepard became the first American in “space” (as we now refer to that region above the sky), taking a 15 minute suborbital ride aboard the Mercury craft Freedom 7.

Return to the Moon tonight to have a look on the terminator near the southern cusp for two outstanding features. The easiest is crater Schickard – a class V mountain-walled plain that spans 227 kilometers. Named for German astronomer Wilhelm Schickard, this beautiful old crater with the subtle interior details has another crater caught on its northern wall named Lehmann.

Look further south for one of the Moon’s most incredible features – Wargentin. Among the many strange things on the lunar surface, Wargentin is unique. Once upon a time, it was a very normal crater and had been that way for hundreds of millions of years – then it happened. Either a fissure opened in its interior, or the meteoric impact that formed it caused molten lava to begin to rise. Oddly enough, Wargentin’s walls were without large enough breaks to allow the lava to escape and it continued to fill the crater to the rim. Often referred to as “the Cheese,” enjoy Wargentin tonight for its unusual appearance and be sure to note Nasmyth and Phocylides as well!

Before we leave, let’s have a look east at 3.34 magnitude Theta Leonis. Also known as Chort, mark this one in your memory, as well as 3.94 magnitude Iota to the south as markers for a galaxy hop. Last is easternmost 2.14 magnitude Beta. Denebola is the “Lion’s Tail” and has several faint optical companions.

Sunday, May 6 – Earlier we learned about awesome magnetic energy, but what happens when you find magnetism in a very unlikely place? Tonight might be Full Moon, but we can still have a look at the lunar surface just a little southeast of the grey oval of Grimaldi. The area we are looking for is called the Sirsalis Rille and on an orb devoid of magnetic fields – it’s magnetic! Like a dry river bed, this ancient “crack” on the surface runs 480 kilometers along the surface and branches in many areas.

For those who like curiosities, our target for tonight will be 1.4 degrees northwest of 59 Leonis, which is itself about a degree southwest of Xi. While this type of observation may not be for everyone, what we are looking for is a very special star – a red dwarf named Wolf 359 (RA 10 56 28.99 Dec +07 00 52.0).

Discovered photographically by Max Wolf in 1959, charts from that time period will no longer be accurate because of the star’s large proper motion. It is one of the least luminous stars known, and we probably wouldn’t even know it was there except for the fact that it is the third closest star to our solar system. Located only 7.5 light-years away, this miniature star is about 8% the size of our Sun – making it roughly the size of Jupiter. Oddly enough, it is also a “flare star” – capable of jumping another magnitude brighter at random intervals. It might be faint and difficult to spot in mid-sized scopes, but Wolf 359 is definitely one of the most unusual things you will ever observe!

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

Posted on by Jenny Winder

The Mystery of Venus’ Ashen Light

Venus imaged by Magellan Image Credit: NASA/JPL

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May is the best time to try and spot one of the most enduring unsolved mysteries in our Solar System. Ashen Light is a faint glow allegedly seen on the unlit portion of Venus, during its crescent phase, similar to the earthshine often observed on the Moon, though not as bright. It is more commonly observed while Venus occupies the evening sky, as now, than when it is in the morning sky. But no one really knows for sure what causes it.

So what’s the history of our knowledge about this enigmatic glow?

The phenomenon was first noted in 1643, by Italian astronomer Giovanni Battista Riccioli. Though many notable astronomers have reported sightings in the 369 years since, including Sir William Herschel and more recently, Sir Patrick Moore, many others have failed to see the effect, leading to claims that it is due to nothing more than observer error, an illusion, atmospheric effect or equipment malfunction. Things are not helped by the fact that nobody has managed to capture an image of Ashen Light, yet.

As the month progresses, Venus nears the Sun, ready for its transit on June 5th to 6th and the planet’s crescent phase will increase in diameter during the month, from 37 arcseconds to 56 arcseconds. The best option for amateur astronomers hoping to catch a fleeting glimpse is to use an occulting bar to block the bright crescent, making any glow present on the unlit portion of Venus, more visible.

There is much controversy and many theories as to the cause of Ashen Light. The Keck 1 telescope on Hawaii reported seeing a subtle green glow and suggested it could be produced as ultraviolet light from the Sun splits molecules of carbon dioxide, known to be common in Venus’ atmosphere, into carbon monoxide and oxygen, but the green light emitted as oxygen recombines to form O2 is thought too faint to explain the effect. Another more likely theory is that multiple lightning strikes are illuminating Venus’ skies. Though the Cassini spacecraft flew by Venus twice on it’s voyage to Saturn and failed to detect the high frequency radio noise we associate with thunderstorms on Earth, in 2007 Venus Express did detect low frequency ‘whistler waves’ that can also result from lightning. It could also be the Venusian equivalent of aurorae.

By far the most bizarre theory, and my personal favourite, was proposed in the early 19th century by the Bavarian astronomer Franz von Gruithuisen, who suggested that Ashen Light was the result of fires lit to clear land for farming on Venus, or to celebrate the coronation of a new Venusian Emperor!

For further reading, a paper on Ashen Light by C. T. Russell and J. L. Phillips

Posted on by Ken Kremer

Outer Space – Mind Blowing Video from Jupiter and Saturn

Video Caption: This mesmerizing video unveils incredibly amazing sequences around Jupiter and Saturn from NASA’s Cassini and Voyager missions set to stirring music by “The Cinematic Orchestra -That Home (Instrumental)”. Credit: Sander van den Berg

Don’t hesitate 1 moment ! Look and listen to this mind blowing video of the Jupiter and Saturnian systems.

If you love the wonders of the hitherto unknown Universe unveiled before your eyes – and long to explore – feast your eyes on this short new video right now titled simply; “Outer Space”. Continue reading “Outer Space – Mind Blowing Video from Jupiter and Saturn”

Posted on by Tammy Plotner

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

Mars In Leo - Credit: John Chumack

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Greetings, fellow SkyWatchers! What a great week to just enjoy some great unaided eye astronomy observations. Who can resist the beautiful appearance of Mars in Leo? Also this week, you’ll enjoy not one – but two – meteor showers as the Mu Virginids come to town mid-week and the Bootids light up the weekend. Get ready to enjoy bright stars, find planets, explore lunar features, learn some astronomy history and much more! When ever you’re ready, meet me in the back yard…

Monday, April 23 – Pioneer quantum physicist Max Planck was born on this day in 1858. In 1900, Max developed the Planck equation to explain the shape of blackbody spectra (a function of temperature and wavelength of emission). A “blackbody” is any object that absorbs all incident radiation – regardless of wavelength. For example, heated metal has blackbody properties because the energy it radiates is thermal. The blackbody spectrum’s shape remains constant, and the peak and height of an emitter can be measured against it – be it cosmic background radiation – or our own bodies.

Now, let’s put this knowledge into action. Stars themselves approximate blackbody radiators, because their temperature directly controls the color we see. A prime example of a “hot” star is Alpha Virginis, better known as Spica. Compare its color to the cooler Arcturus… What colors do you see? There are other astronomical delights that radiate like blackbodies over some or all parts of the spectrum as well. You can observe a prime example in a nebula such as M42, in Orion. By examining the radio portion of the spectrum, we find the temperature properly matches that of electrons involved in the process of fluorescence. Much like a common household fixture, this process is what produces the visible light we can see.

Tuesday, April 24 – Today in 1970, China launched its first satellite. Named Shi Jian 1, it was a successful technological and research craft. This achievement made China the fifth country to send a vessel into space.

Tonight see if you can spot the tender beginnings of the Moon after sunset. Observers take pleasure in sweeping the sky with small scopes and binoculars in hopes of finding the thinnest possible lunar crescent. And speaking of crescents, did you spot Venus close to the Moon? Why not take out your telescope and see what phase Venus is now in. If you don’t have a filter to cut its bright glare, try wearing sunglasses!

No telescope? No problem. You can still do some very awesome astronomy with just your eyes! Begin with locating the northern constellation of Ursa Major – most commonly known as the “Big Dipper”. Take note of the curve of the Dipper’s “handle” and trace it from the bottom of the cup and continue on the “Arc to Arcturus”. Keep moving, because now you’re going to “Speed on to Spica”! Once you’ve located this bright, blue/white star, simply look to its east/southeast (or upper left) for a yellow appearing “star”. That’s no star… That’s Saturn!

Now let’s have a look at 140 light-year distant Epsilon Hydrae – the northernmost star in the small circlet east of Procyon. While it and Rho will make a beautiful visual double for binoculars, Epsilon itself is a multiple system. Its A and B components are a tough split for any scope, but the 8th magnitude C star is easier. The D component is a dwarf star.

Wednesday, April 25 – Today marks the 15th anniversary of the deployment of Hubble Space Telescope. While everyone in the astronomical community is well aware of what this magnificent telescope “sees,” did you know that you can see it with just your eyes? The HST is a satellite that can be tracked and observed. Visit heavens-above.com and enter your location. This page will provide you with a list of visible passes for your area. Although you can’t see details of the scope itself, it’s great fun to track with binoculars or see the Sun glinting off its surface in a scope.

Tonight our first voyage is to the Moon’s surface. Look along the terminator in the southern quadrant and revisit ancient old crater Furnerius. Named for French Jesuit mathematician George Furner, this crater spans approximately 125 kilometers and is a lunar club challenge. Power up and look for two interior craters. The smaller is crater A and it spans a little less than 15 kilometers and drops to a depth of over 1000 meters. The larger crater C is about 20 kilometers in diameter, but goes far deeper, to more than 1400 meters. That’s about as deep as a coral will grow under the Earth’s oceans!

Keep a watch on the skies while you’re out as the Mu Virginid meteor shower reaches its peak at 7 to 10 per hour. With dark skies tonight, you still might catch one of these medium speed meteors radiating from a point near the constellation of Libra.

Thursday, April 26 – On this date in 1920, the Shapely-Curtis debate raged in Washington on the nature of and distance to spiral nebulae. Shapely claimed they were part of one huge galaxy to which we all belonged, while Curtis maintained they were distant galaxies of their own. Thirteen years later on the same date, Arno Penzias was born. He went on to become a Nobel Prize winner for his part in the discovery of the cosmic microwave background radiation, through searching for the source of the “noise” coming from a simple horn antenna. His discovery helped further our understanding of cosmology in ways that Shapely and Curtis could have never dreamed of.

Perhaps they dreamed of Moon? We’ve got Moon! No matter, what we really want to do is revisit and study a changeable, sometimes transient, and eventually bright feature on the lunar surface – crater Proclus. At around 28 kilometers in diameter and 2400 meters deep, Proclus will appear on the terminator on the west mountainous border of Mare Crisium. For many viewers tonight, it will seem to be about 2/3 black, but 1/3 of the exposed crater will be exceptionally brilliant – and with good reason. Proclus has an albedo, or surface reflectivity, of about 16%, which is an unusually high value for a lunar feature. Watch this area over the next few nights as two rays from the crater will widen and lengthen, extending approximately 322 kilometers to both the north and south. Congratulations on another lunar club challenge!

Friday, April 27 – Tonight we’re heading towards the lunar surface to view a very fine old crater on the northwest shore of Mare Nectaris – Theophilus. Slightly south of mid-point on the terminator, this crater contains an unusually large multiple-peaked central mountain which can be spotted in binoculars. Theophilus is an odd crater, one that is a parabola – with no area on the floor being flat. It stretches across a distance of 100 kilometers and dives down 440 meters below the surface. Tonight it will appear dark, shadowed by its massive west wall, but look for sunrise on its 1400 meter summit!

Now, let’s try picking up a globular cluster in Hydra that is located about 3 fingerwidths southeast of Beta Corvus and just a breath northeast of double star A8612 – M68 (Right Ascension:12 : 39.5 – Declination: -26 : 45). This class X globular was discovered in 1780 by Charles Messier and first resolved into individual stars by William Herschel in 1786. At a distance of approximately 33,000 light-years, it contains at least 2000 stars, including 250 giants and 42 variables. It will show as a faint, round glow in binoculars, and small telescopes will perceive individual members. Large telescopes will fully resolve this small globular to the core!

While you’re out, have a look at 27 Hydrae about a fingerwidth southwest of Alpha. It’s an easy double for any equipment with its slightly yellow 5th magnitude primary and distant, white, 7th magnitude secondary. Although it is wide, the pair is a true binary system.

Saturday, April 28 – Today was a very busy day in astronomy history. Newton published his Principia in 1686 on April 28. In 1774, Francis Baily was born. He went on to revise star catalogs and explain the phenomenon at the beginning and ending of a total solar eclipse which we know as “Baily’s Beads.” 1900 saw the birth of Jan Hendrick Oort, who quantified the Milky Way’s rotation characteristics and envisioned the vast, spherical area of comets outside our solar system that we now call the Oort Cloud. Last, but not least, was the birth of Bart Jan Bok in 1906 who studied the structure and dynamics of the Milky Way.

Tonight’s outstanding lunar feature will be crater Maurolycus just southwest of the three rings of Theophilus, Cyrillus and Catharina. This lunar club challenge spans 114 kilometers and goes below the lunar surface by 4730 meters. Be sure to look for Gemma Frisius just to its north.

Now let’s check out a dandy little group of stars that are about a fistwidth southeast of Procyon and just slightly more than a fingerwidth northeast of M48. Called C Hydrae, this group isn’t truly gravitationally bound, but is a real pleasure to large binoculars and telescopes of all sizes. While they share similar spectral types, this mixed magnitude collection will be sure to delight you!

For SkyWatchers, no equipment is necessary to enjoy the Alpha Bootid meteor shower – despite the Moon. Pull up a comfortable seat and face orange Arcturus as it climbs the sky in the east. These slow meteors have a fall rate of 6 to 10 per hour and leave very fine trails, making an evening of quiet contemplation most enjoyable.

Sunday, April 29 – Before we explore space, let’s have a look at the Moon and the close apparition of Regulus and Mars! The three make a wonderful “line up” the night sky! Now, let’s start our lunar observations tonight as challenge craters Cassini and Cassini A come into view just south of the black slash of the Alpine Valley. 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.

While we’re out, have a look at R Hydrae about a fingerwidth east of Gamma – which is a little more than fistwidth south of Spica. R is a beautiful, red, long-term variable first observed by Hevelius in 1662. Located about 325 light-years from us, it’s approaching – but not that fast. Be sure to look for a visual companion star as well!

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

Many thanks to John Chumack of Galactic Images for his outstanding photo of “Leo In Mars”!