Posted on by Nancy Atkinson

Spiral Galaxies Could Eat Dwarfs All Across the Universe

Stellar streams around the galaxy M 63. Credit: R. Jay Gabany (Blackbird Obs.) in collaboration with D. Martinez-Delgado (MPIA and IAC) et al.

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For years, astronomers have seen evidence that – at least in our own local neighborhood — spiral galaxies are consuming smaller dwarf galaxies. As they are digested, these dwarf galaxies are severely distorted, forming structures like strange, looping tendrils and stellar streams that surround the cannibalistic spirals. But now, for the first time, a new survey has detected such tell-tale structures in galaxies more distant than our immediate galactic neighborhood, providing evidence that this galactic cannibalism might take place on a universal scale. Remarkably, these cutting-edge results were obtained with small, amateur-sized telescopes.


Since 1997, astronomers have seen evidence that spirals in our local group of galaxies are swallowing dwarfs. In fact, our own Milky Way is currently in the process of eating the Canis Major dwarf galaxy and the Sagittarius dwarf galaxy. But the Local group with its three spiral galaxies and numerous dwarfs is much too small a sample to see whether this digestive process is happening elsewhere in the Universe. But an international group of researchers led by David Martínez-Delgado from the Max Planck Institute for Astronomy recently completed a survey of spiral galaxies at distances of up to 50 million light-years from Earth, discovering the tell-tale signs of spirals eating dwarfs.

For their observations, the researchers used small telescopes with apertures between 10 and 50 cm, equipped with commercially available CCD cameras. The telescopes are located at two private observatories — one in the US and one in Australia. They are robotic telescopes that can be controlled remotely.

During the “eating” process, when a spiral galaxy is approached by a much smaller companion, such as a dwarf galaxy, the larger galaxy’s uneven gravitational pull severely distorts the smaller star system. Over the course of a few billions of years, tendril-like structures develop that can be detected by sensitive observation. In one typical outcome, the smaller galaxy is transformed into an elongated “tidal stream” consisting of stars that, over the course of additional billions of years, will join the galaxy’s regular stellar inventory through a process of complete assimilation. The study shows that major tidal streams with masses between 1 and 5 percent of the galaxy’s total mass are quite common in spiral galaxies.

One of the galaxies in the survey, NGC 4651, sports a remarkable umbrella-like structure. It is composed of tidal star streams, the remnants of a smaller satellite galaxy which NGC 4651 has attracted and torn apart. This galaxy's distance from Earth is 35 million light-years.Credit: R. Jay Gabany (Blackbird Obs.) in collaboration with D. Martínez-Delgado (MPIA and IAC) et al.

Detailed simulations depicting the evolution of galaxies predict both tidal streams and a number of other distinct features that indicate mergers, such as giant debris clouds or jet-like features emerging from galactic discs. Interestingly, all these various features are indeed seen in the new observations – impressive evidence that current models of galaxy evolution are indeed on the right track.

Smaller satellite galaxies caught by a spiral galaxy are distorted into elongated structures consisting of stars, which are known as tidal streams, as shown in this artist's impression. Credit: Jon Lomberg

The ultra-deep images obtained by Delgado and his colleagues open the door to a new round of systematic galactic interaction studies. Next, with a more complete survey that is currently in progress, the researchers intend to subject the current models to more quantitative tests, checking whether current simulations make the correct predictions for the relative frequency of the different morphological features.

While larger telescopes have the undeniable edge in detecting very distant, but comparatively bright star systems such as active galaxies, this survey provides some of the deepest insight yet when it comes to detecting ordinary galaxies that are similar to our own cosmic home, the Milky Way. The results attest to the power of systematic work that is possible even with smaller instruments.

For more images see this page from the Max Planck Institute for Astronomy

*Note: Originally the lead image image was credited incorrectly, and is actually a product of R. Jay Gabany, an astrophotographer whose work has been featured quite often here on Universe Today. See more of his amazing handiwork at his website, Cosmotography.

Source: Max Planck Institute for Astronomy

Posted on by Nancy Atkinson

Clearing the Confusion on Neptune’s Orbit

This week Neptune will return to the spot where it was discovered in 1846, in the constellation Capricornus. The planet will complete its first orbit, since being discovered, in 2011. Credit: Starry Night Software, via Space.com

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Last week, Space.com had a great article about how on August 20, 2010, Neptune finally completed one orbit around the Sun since its discovery in 1846, and was now back to its original discovery position in the night sky . The original article was widely quoted, and created a lot of buzz on Twitter, Facebook and other websites. But then, later in the day some contradictory info came out, culminating with Bill Folkner, a technologist at JPL declaring via Twitter: “Neptune will reach the same ecliptic longitude it had on Sep. 23, 1846, on July 12, 2011.” Space.com ended up amending their article, but why the confusion? And could both statements be true? Depending on your perspective, perhaps yes.

“These apparently contradictory statements highlight the problems of defining planetary orbits,” astronomer Brian Sheen from the Roseland Observatory in the UK told Universe Today. “There are two ways of following the progress of a planet around the Sun/night sky.”

The first is from the perspective of being on planet Earth (specifically at the center of our planet) – called geocentric longitude, Sheen said, also known as right ascension.

The second is from the perspective of being on the Sun (specifically at the center of the Sun and indeed our solar system) which is called heliocentric longitude, and also ecliptic longitude.

“The orbital period of a planet is measured with reference to the heliocentric longitude, in the case of Neptune this is 164.8 years,” Sheen explained. “The problem of referencing via geocentric longitude is that the Earth itself is orbiting the Sun and therefore changing its relative position to the other planet, this case, Neptune.”

Neptune was discovered Sept 23, 1846. Adding 164.8 years to that date brings us to July 2011, and specifically 12th July. However taking the Earth’s motion into account we have a number of close approaches. Confusion about this situation is exacerbated by the fact that Neptune retrogrades at opposition.

And so, in April and July of this year (2010), Neptune came very close to returning to its apparent position in the sky at the time of its discovery (in geocentric right ascension and declination), actually much closer than it will be next year when it returns to its 1846 heliocentric longitude. It’s location at discovery and currently is in the constellation Capricornus.

But still, Neptune will not complete its first orbit since being discovered until in 2011.

“Given a discovery date of 23rd Sept 1846 and an orbital period of 164.8 years gives a return date of well into 2011 and a rough check gives 9-13 July,” Sheen said. “This accords well with the given date of 12th July.”

This gives us a celebration to look forward to in 2011!

Posted on by Nancy Atkinson

Amazing Sunspot Image from New Solar Telescope

The most detailed sunspot ever obtained in visible light was seen by new telescope at NJIT's Big Bear Solar Observatory. Credit: Big Bear Solar Observatory

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A new type of adaptive optics for solar observations has produced some incredible results, providing the most detailed image of a sunspot ever obtained in visible light. A new telescope built by the New Jersey Institute of Technology’s Big Bear Solar Observatory has seen its ‘first light’ using a deformable mirror, which is able to reduce atmospheric distortions. This is the first facility-class solar observatory built in more than a generation in the U.S.

The New Solar Telescope (NST) is located in the mountains east of Los Angeles. It has 97 actuators that make up the deformable mirror. By the summer of 2011, in collaboration with the National Solar Observatory, BBSO will have upgraded the current adaptive optics system to one utilizing a 349 actuator deformable mirror. The telescope has a 1.6 m clear aperture, with a resolution covering about 50 miles on the Sun’s surface.

The NST will be the pathfinder for an even larger ground-based telescope, the Advanced Technology Solar Telescope to be built over the next decade. Philip R. Goode from NJIT is leading a partnership with the National Solar Observatory (NSO) to develop a new and more sophisticated kind of adaptive optics, known as multi-conjugate adaptive optics. This new optical system will allow the researchers to increase the distortion-free field of view to allow for better ways to study these larger and puzzling areas of the Sun, and a 4-meter aperture telescope will be built in the next decade.

Source: NJIT

Posted on by Nancy Atkinson

Jupiter Gets Smacked Yet Again?

It looks like once again, Jupiter has taken a hit! And once again an amateur astronomer spotted and captured the event. Masayuki Tachikawa was observing Jupiter on at 18:22 Universal Time on August 20th (early on August 21 in Japan) and his video camera captured a 1-second-long flash on the planet’s disk, along the northern edge of the gas giant’s North Equatorial Belt. The event was reported by astronomer Junichi Watanabe from the National Astronomical Observatory of Japan, on his blog.
Continue reading “Jupiter Gets Smacked Yet Again?”

Posted on by Tammy Plotner

Observing Spotlight – Dropping In On Jupiter…

Parallel/Cross-Eye 3D Image - Click For Full Size

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“Now that she’s back in the atmosphere, with drops of Jupiter in her hair…” Oh! Hey, there! Come on over and have a seat. Yeah, I really like that “Train” song, too. While the Moon is putting the brakes on deep sky observing, why don’t you take a look though the magnificent eye of the 9″ TMB refractor of Dietmar Hager and we world-wide friends can spend a little quality time together with Jupiter.

Here… You look through the eyepiece of a little telescope for awhile and I’ll tell you some of the things we know about this giant planet.

What’s that you say? Yes. Jupiter is big… Big enough to hold the mass of 1,000 Earths and about 1/10 the size of our Sun. Its a heavy-weight, too… But, believe it or not, Jupiter’s density is only about 1/4 of that of Earth’s. Scientists think this means the giant planet consists mostly of hydrogen and helium around a core of heavy elements. That means Jupiter more closely resembles a sun instead of a planet! Yeah… It’s hot there, too. As a matter of fact, Jupiter is putting out twice as much heat as it receives from Sol. Near the core temperature may be about 43,000 degrees F (24,000 degrees C)… Even hotter than the surface of the Sun. Hot enough to get a burn? Darn right. Those subtle tones of red and brown are chemical reactions much like what happens when we humans get a sunburn.

I see you smiling in the dark. Are you starting to notice details Jupiter’s cloud bands? Even a small telescope shows these areas called “zones”. This is where chemicals have formed colorful layers of clouds at different heights. The white belts are made of crystals of frozen ammonia and they are positioned much higher than the dark belts. Of course, you know all about the “Great Red Spot”, but sometimes it’s pretty hard to see unless you know when to look. Jupiter makes a complete rotation in about 10 hours, so even if you can’t see something right now – you can wait awhile and it will come around.

Speaking of coming around, did you notice how close one of Jupiter’s moon is getting to the edge of the planet? Then keep watching because we’re about to see a transit happen. Jupiter has at least 60 moons, but 4 of them are bright and very easy to see even in binoculars. They were discovered by Galileo, and that’s why you’ll sometimes hear them called the “galiean moons”. When they zip around behind Jupiter in their orbit, it’s called a occultation – but when they go in front of the planet from our point of view, it’s called a tranist. The really fun part is that you can not only see the little moon going across the surface, but a few minutes later? You can see the shadow, too! Here’s a little bit of magic from another friend of ours named Sander Klieverik.

Click to start animation...

Isn’t that just the coolest? You’re going to be hearing a lot about Sander’s work here in the near future. And there’s going to be a great Jupiter event he wants to make sure you know about!

“On October 31, 2010 Europa and Ganymede will simultaneously cross the cloud tops of Jupiter from 02:26 till 03:21 UT as do their shadows from 04:17 UT till 07:00 UT. Timing of entrance of the first moon, Ganymede will be around 00.20 UT, following by Europe at 02:26 UT. The first shadow will appear 04:09, quickly followed by Europe’s shadow at 04:16. Two shadows in very close proximity should be a very beautiful view! Circumstances are favourable as Jupiter has a visual diameter of around 48 arc seconds, being a month after opposition in which Jupiter reached almost 50 arc seconds (minimum 33″). For the non-astronomers, when a planet is in opposition it is roughly closest to the Earth at this point of its orbit, making it appear bigger and brighter. At that moment it is visible almost all night, rising around sunset, culminating around midnight and setting around sunrise.”

In the meantime, why don’t you keep practicing timing galiean events and seeing them? Here’s a handy Jupiter Moon Tool, and Sander has also prepared a Jupiter Almanac as well!

“But tell me, did the wind sweep you off your feet? Did you finally get the chance to dance along the light of day… And head back to the Milky Way? And tell me, did Venus blow your mind? Was it everything you wanted to find? And did you miss me 1hile you were looking for yourself out there?”

Now, quit bogarting that eyepiece… It’s my turn!

Many thanks to the one and only Dietmar Hager, Jupiter Video courtesy of Northern Galactic and the up and coming Sander Klieverik’s “AstronomyLive”. Song lyrics – “Drops of Jupiter” are from the artists “Train”. Let’s keep on rockin’ the night!

Posted on by Tammy Plotner

Clockwork Planets

Bottoms up! Mercury, Moon, Saturn, Venus, Mars...

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While the Perseid meteor shower has been putting on quite a show, there’s an awesome “no telescope needed” eye-catching apparition that only requires a clear western skyline. If you haven’t been watching the planets – Mercury, Saturn, Venus and Mars – line up like clockwork, then don’t despair. You have a few more days yet!

While the uniformed all-too-often see “signs of bad portent” in a planetary alignment, the rest of us know this is a perfectly normal function of our solar system called a conjunction. This is a simple positional alignment as seen (usually from Earth’s viewpoint) from any given vantage point. The world isn’t going to end, the oceans aren’t going to rise… and Mars is darn-sure not going to be the size of the Moon. All alignments of at least two celestial bodies are merely coincidental and we even have a grand name for what’s happening – an appulse.

When planets are involved, their near appearance usually happens in the same right ascension. They really aren’t any closer to each other than what their orbital path dictates – it just appears that way. In the same respect, there is also conjunction in ecliptical longitude. But, if the planet nearer the Earth should happen to pass in front of another planet during a conjunction it’s called a syzygy!

One thing is for sure… You don’t have to be a syzy-genius to simply enjoy the show and the predictable movements of our solar system. Just find an open western skyline and watch as twilight deepens. Tonight the Moon will be directly south of Venus and over the next couple of days the planetary alignment will gradually separate as brilliant Venus seems to hold its position, while Mars, Saturn and Mercury drift north. Enjoy the show! Because just like the yearly Mars/Moon Myth?

It happens like clockwork…

Many, many thanks to the incredible Shevill Mathers for providing us with this breathtaking photo. (Do you know just how hard it is to get a shot like that without over or under exposing? I dare you to try it…) Every fox has a silver lining!

Posted on by Tammy Plotner

2010 Perseid Meteor Shower


In just a few days – during the evening hours of August 12 and morning of August 13 – one of the year’s most reliable meteor showers is about to grace this year’s dark skies. Not only will we be in for some celestial fireworks, but the planets are going to put on a show as well. Who, what, when, where, why and how? Then step inside and let’s talk about the 2010 Perseid meteor shower…

During the latter half of July and the beginning of August, the Earth cruises through several minor cometary debris streams – producing equally minor meteor showers which meander through the constellations of Cygnus, Capricornus and Aquarius. This is the type of normal activity which is enjoyed by both the northern and southern hemisphere. One any given good, dark night, you might spot as many as a dozen meteors during an evening’s observing session. It’s a nice transition in the weather for both halves of Earth and this period of time makes for comfortable watching. While I love catching a sparkling trail when I really wasn’t expecting or waiting for one, there’s nothing in the heavens that can make me yell out loud like being witness to a productive meteor shower.


And the Perseids produce…

Where exactly did all the “stuff” come from that causes the annual Perseid meteor shower to be so reliable? Try periodic comet 109P/Swift-Tuttle. Discovered in 1862, Swift-Tuttle is called “periodic” because it makes a pass through our solar system about every 133-135 years leaving behind a debris trail. As early as 36 AD, Chinese astronomers began to notice a sharp peak of meteor activity during this time and began keeping record. Other astronomers followed suit until astronomy became a rather dangerous occupation and facts and figures began to dwindle. Although often referred to as “the tears of St. Lawrence” to celebrate the martyr’s death on August 10, it wasn’t until 1835 and Adolphe Quetelet that the annual Perseid was actually given credit to an individual for pinpointing its radiant and peak date.

Within four years, sharp-eyed observers had not only began to note the Perseid presence, but to make an accurate hourly account of the fall rate as well. In 1839, E. Heis gave us his first written documentation of a maximum rate of 160 per hour and over the next several decades, many other observers joined him. What they noticed through their observations was the fall rate changed from year to year… Why?

Between 1864 and 1866, Giovanni Schiaparelli also took an interest in the Perseids and computed the stream’s orbit. What he discovered was astounding. It nearly matched that of a comet discovered just two years earlier – 109P/Swift-Tuttle. After that, it didn’t take very long to figure out each high spike in fall rates also corresponded with the comet’s known perihelion. It was the very first time a meteor shower had been positively identified with a comet!

But, when it comes to science, proving a speculation is everything. Record keeping for that period of time wasn’t exactly the best and in 1973 astronomer Brian Marsden was busy trying to predict the return of comet Swift/Tuttle. His chosen date was 1981 and as annual activity of the Perseid meteor shower increased, so did the excitement of recapturing the comet. However, like so many astronomical predictions, the traveler from Oort Cloud failed to make its debut appearance Needless to say, between disappointment and lunar interference, interest in the Perseid’s cometary originator quickly faded. However, Marsden wasn’t about to give up. Choosing another documented comet seen in 1737, he made another prediction… Swift/Tuttle would return in 1992.

This time was sweet success.

With 18 years between now and comet Swift/Tuttle’s last perihelion, will the 2010 Perseid meteor activity be a smashing shower or a dwindling display? It’s really hard to say because the stream is so wide and complex. We know when the Earth passes through this outgassing of materials that we can expect a certain amount of activity during a marginal time period – but we can only make a guess at how much material was expelled. There may have been time centuries ago when the comet did something very unexpected (as comets have a way of doing) and left a dense cloud just waiting for us to orbit through… And it may be burning itself out during each successive pass around Sol. So many things can happen! Jupiter may have affected the stream’s position – or a huge flurry of activity might occur during daylight. But what about this year?

Thankfully there will be no Moon to obscure fainter meteors and zenith hourly rates may approach up to nearly 100 per hour. But that’s a very optimistic estimate since the Perseids are notoriously fast – burning through our atmosphere at 140,000 mph – and sometimes very faint. As the evening begins, facing east/northeast will be best for most northern hemisphere observers, and follow Perseus to the north as it rises. Unfortunately, southern hemisphere observers aren’t likely to see any of this activity – but it never hurts to keep watch to the northern horizon if you’re out. If you have to be selective about the times you watch, the very best views will be had when the constellation is at its highest – after local midnight through local dawn.

Don’t wait until the peak date to begin your observations. Perseid activity is already underway at 15 to 20 per hour and the fall rate will only continue to increase as it nears the night of August 12/13th when up to 75 meteors may grace the starry skies. If you live in a light polluted area, make plans to get rural. Many farmers and home owners in the countryside are more than happy to grant you permission to choose a safe observing spot on their land if you explain what you’re doing – so ask! Be sure to take along things which will aid in your comfort, such as a reclining lawn chair or blanket (meteor neck sucks). Make it a popcorn and soda family event! But stay away from white light. If being in the wild scares you a bit, create your own “night vision friendly” flashlight by stretching a red balloon over the lens. If you arrive at sunset? Then check out the beautiful conjunction of Mercury Mars, Saturn, Venus and the very tender crescent Moon….

Wishing you clear skies and the very best of luck!

Here’s information on the 2009 Perseids.

Posted on by Tammy Plotner

Observing Spotlight – Whatever Happened to M71?

The M71 Globular Cluster, as pictured by the Hubble space telescope. Credit: NASA

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In our rush to look at the bright and beautiful objects in the night, we often overlook celestial curiosities in favor of a more splashy neighbor. How many times have you looked at the Andromeda Galaxy, but really didn’t take the time to power up and study M110? Perhaps you spent a whole evening studying the intricacies of the Great Orion Nebula – but totally forgot about striking M78? It’s the way of things. But, next time you drop by the Dumbbell Nebula, spend some Hubl time with the sparkling stars of Messier 71…

Discovered by Philippe Loys de Cheseaux in 1746 and researched by Charles Messier then added his catalog of comet-like objects in 1780, this brilliant globular cluster let’s its presence be known at a distance of about 12,000 light years away from Earth. Covering an area measuring approximately 27 light years across, it shines with a luminosity of around 13,200 suns – not bad for a conglomeration of stars which could be as old as 9-10 billion years. Until about four decades ago, Messier 71 was believed to be a dense galactic cluster – nearly devoid of RR Lyrae “cluster” variable stars and rich in metallicity.

And a concentrated cluster of stars it stayed until modern H-R diagram photometry picked up a short “horizontal branch” in its structure…

Who remembers to stop and study? While grandiose images like our Hubble lead-in photo might pique your curiosity for a moment, it’s the deep sky dedication and devotion revealed in the work of Bernhard Hubl which ignites the sense of wonder all over again…

M71 by Bernhard Hubl

Reach out and touch M71 for yourself. Located in the constellation of Sagitta at RA:19h 53m 48s Dec: +18°47′ and close to magnitude 7, it’s easily caught in average binoculars from a dark sky location, beauty revealed in smaller telescopes and breathtakingly resolved in large aperture telescopes. It’s really not hard to find if you just take the time to let your eyes relax to see Sagitta’s faint arrow-shaped signature asterism. Just aim mid-way between Gamma and Delta and be swept away…

Because it’s full of stars.

Many thanks go to Bernhard Hubl of Northern Galactic for his untold hours of work just to share the inspiration!

Posted on by Nicholos Wethington

Telescope’s Laser Pointer Clarifies Blurry Skies

The new laser adaptive optics system in action. At Mount Hopkins in Arizona, a bundle of five lasers is shot into the atmosphere to improve the imaging of the 6.3-meter MMT telescope. Image Credit: Thomas Stalcup

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While it’s handy for us humans (and all of the other life on our planet for that matter), the atmosphere is almost universally cursed among astronomers. It’s great for breathing, but when it comes to astronomical observations of faint objects, all the atmosphere tends to do is muck up the view. In the past 20 years, development of adaptive optics – essentially telescopes that change the shape of their mirrors to improve their imaging capability – has dramatically improved what we can see in space from the Earth.

With a new technique involving lasers (Yes! Lasers!), the images capable with an adaptive optics telescope could be nearly as crisp as those from the Hubble Space Telescope over a wide field of view. A team of University of Arizona astronomers led by Michael Hart has developed a technique that helps calibrate the surface of the telescope very precisely, which leads to very, very clear images of objects that would normally be very blurry.

Laser adaptive optics in telescopes are a relatively new development in getting better image quality out of ground-based telescopes. While it’s nice to be able to use space-based telescopes like the Hubble and the forthcoming James Webb Space Telescope, they are certainly expensive to launch and maintain. On top of that, there are a lot of astronomers competing for very little time on these telescopes. Telescopes like the Very Large Telescope in Chile, and the Keck Telescope in Hawaii both already use laser adaptive optics to improve imaging.

Initially, adaptive optics focused in on a brighter star near the area of the sky that the telescope was observing, and actuators in the back of the mirror were moved very rapidly by a computer to cancel out atmospheric distortions. This system is limited, however, to areas of the sky that contain such an object.

Laser adaptive optics are more flexible in their usability – the technique involves using a single laser to excite molecules in the atmosphere to glow, and then using this as a “guide star” to calibrate the mirror to correct for distortions caused by turbulence in the atmosphere. A computer analyzes the incoming light from the artificial guide star, and can determine just how the atmosphere is behaving, changing the surface of the mirror to compensate.

In using a single laser, the adaptive optics can only compensate for turbulence in a very limited field of view. The new technique, pioneered at the 6.5-m MMT telescope in Arizona, uses not just one laser but five green lasers to produce five separate guide stars over a wider field of view, 2 arc minutes. The angular resolution is less than that of the single laser variety – for comparison, the Keck or VLT can produce images with a 30-60 milli-arcsecond resolution, but being able to see better over a wider field of view has many advantages.

In the image on the left, the cluster M3 appears blurry with the laser adaptive optics system turned off. Things are much clearer using the system, and individual stars in the cluster become visible, as can be seen in the image on the right. Image Credit: Michael Hart

The ability to take the spectra of older galaxies, which are very faint, is possible using this technique. By taking their spectra, scientists are better able to understand the composition and structure of objects in space. Using the new technique, taking the spectra of galaxies that are 10 billion years old – and thus have a very high red shift – should be possible from the ground.

Supermassive clusters of stars would also be more easily scrutinized using the technique, as images taken in a single pointing of the telescope on different nights would allow astronomers to understand just which stars are part of the cluster and which are not gravitationally bound.

The results of the team’s efforts was published in the Astrophysical Journal in 2009, and the original paper is available here on Arxiv.

Source: Eurekalert, Arxiv paper

Posted on by Tammy Plotner

Weekend SkyWatcher’s Forecast: July 16-19, 2010

Greetings, fellow SkyWatchers! Are you ready for a rock the night weekend? Then come along as you won’t need a telescope to watch the movement of the planets and the Perseid meteor shower heating up your evenings! If you’d still like a challenge, then why not chase bright asteroid Ceres with binoculars – or look up a challenging globular cluster? If you still need appeal, then there are a couple of great stars that are worth observing… and learning about! Whenever you’re ready, I’ll see you in the backyard….

July 16, 2010 – Today celebrates the 1746 birth of Giuseppe Piazzi. Although we know Piazzi best for his discovery of the asteroid Ceres, did you know he was also the first to notice that 61 Cygni had a large proper motion? Nine days and 38 years later, the man responsible for measuring 61 Cygni, Friedrich Bessel, was born.

This would indeed be a great evening to check out asteroid Ceres for yourself. You’ll find it in Ophiuchus and well placed for either binoculars or a small telescope just above the “sting” of the Scorpion! Here’s a map to help you along the way…


Now let’s take a look at gorgeous 61 Cygni. You’ll easily locate it between Deneb and Zeta on the eastern side. Look for a small trio of just visible stars and choose the westernmost (RA 21 06 54 Dec +38 44 44). Not only is it famous because of Piazzi and Bessel’s work, but it is one of the most noteworthy of double stars for a small telescope. Of the unaided visible stars, 61 is the fourth closest 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″ to the south-southeast. Back in 1792, Piazzi first noticed its abnormally large proper motion and dubbed it the ‘‘Flying Star.’’ At that time, it was only separated by around 10″, and the B star was to the northeast. It takes nearly seven 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!

July 17, 2010 – This date marks the 1904 passing of Isaac Roberts, an English astronomer who specialized in photographing nebulae. As an ironic twist, this is also the date on which a star was first photographed at Harvard Observatory!

Tonight let’s have a look at a real little powerpunch globular cluster located in northern Lupus—NGC 5824. Although it’s not an easy star hop, you’ll find it about 7 degrees southwest of Theta Librae, and exactly the same distance south of Sigma Librae (RA 15 03 58 Dec –33 04 04). Look for a 5th magnitude star in the finderscope to guide you to its position southeast.


A Class I globular cluster, you won’t find any others that are more concentrated than this. Holding a rough magnitude of 9, this little beauty has a deeply concentrated core region that is simply unresolvable. Discovered by E.E. Barnard in 1884, it enjoys its life in the outer fringes of its galactic halo about 104 thousand light-years away from Earth and contains many recently discovered variable stars.

Oddly enough, this metal-poor globular may have been formed by a merger. Research on NGC 5824’s stellar population leads us to believe that two less dense and differently aged globulars may have approached one another at a low velocity and combined to form this ultra-compact structure. Be sure to mark your observing notes on this one! It also belongs to the Bennett catalog and is part of many globular cluster lists.

July 17, 2010 – Celestial scenery alert! Are you watching the planet dance as Mars heads towards Saturn? You don’t need a telescope to enjoy the early evening trio of bright Venus along the western horizon – or the duet just above it! While you’re out enjoying a relaxing evening, keep your eyes on the skies. The early activity of the annual Perseid meteor shower is really heating up and you can expect to see several “shooting stars” an hour!


Tonight let’s begin with the 1689 birth of Samuel Molyneux. This British astronomer and his assistant were the first to measure the aberration of starlight. What star did they choose? Alpha Draconis, which oscillated with an excursion of 39’’ from its lowest declination in May. Why choose a single star during an early dark evening? Because Alpha Draconis—Thuban—is far from bright.


At magnitude 3.65, Thuban’s ‘‘alpha’’ designation must have come from a time when it, not Polaris, was the northern celestial pole star. If you’re aware that the two outer stars of the ‘‘dipper’’ point to Polaris, then use the two inner stars to point to Thuban (RA 14 04 23 Dec +64 22 33). This 300-light-year distant white giant is no longer main sequence, a rare binary type.

Now head to binary Eta Lupi, a fine double star resolvable with binoculars. You’ll find it by staring at Antares and heading due south two binocular fields to center on bright H and N Scorpii— then one binocular field southwest. Now hop 5 degrees southeast (RA 16 25 18 Dec –40 39 00) to encounter the fine open cluster NGC 6124. Discovered by Lacaille, and known as object I.8, this 5th magnitude open cluster is also Dunlop 514, Melotte 145, and Collinder 301. Situated about 19 light years away, it shows a fine, round, faint spray of stars to binoculars and is resolved into about 100 stellar members to larger telescopes. AlthoughNGC6124 is low for northern observers, it’s worth the wait to try at culmination. Be sure to mark your notes because this delightful galactic cluster is also a Caldwell object and counts for a southern skies binocular award.

Until next week? Keep capturing photons!

This week’s awesome images are (in order of appearance): 61 Cygni, NGC 5824, Alpha Draconis and NGC 6124 are from Palomar Observatory, courtesy of Caltech. Maps are courtesy of “Your Sky”. We thank you so much!