Posted on by Nancy Atkinson

Conduct Virtual Explorations of Mars with New WorldWide Telescope Feature

Screenshot showing Olympus Mons in 3-D using the World Wide Telescope.

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Love 3-D imagery of Mars? There’s now a firehose just for you! The WorldWide Telescope has teamed up with NASA to use images from the Mars Reconnaissance Orbiter’s HiRISE camera to provide a high-resolution 3-D map of the Red Planet. Included are fully-interactive images and the latest and greatest NASA data, which will allow for a virtual way to explore Mars and perhaps to even make your own scientific discoveries. This is the highest-resolution fully interactive map of Mars ever created, and includes guided video tours with two NASA scientists, James Garvin of NASA’s Goddard Space Flight Center in Greenbelt, Md., and Carol Stoker of Ames.

Garvin’s tour walks viewers through the geological history of Mars and discusses three possible landing sites for human missions there. Each landing site highlights a different geological era of the planet.

Stoker’s tour addresses the question: “Is there life on Mars?” and describes the findings of NASA’s Mars Phoenix Lander.

The Intelligent Robotics Group at Ames Research Center developed open source software that runs on the NASA Nebula cloud computing platform to create and host the high-resolution maps. The maps contain 74,000 images from Mars Global Surveyor’s Mars Orbiter Camera and more than 13,000 high-resolution images of Mars taken by the Mars Reconnaissance Orbiter’s High Resolution Imaging Science Experiment (HiRISE) camera. Each individual HiRISE image contains more than a billion pixels. The complete maps were rendered into image mosaics containing more than half a billion smaller images.

“These incredibly detailed maps will enable the public to better experience and explore Mars,” said Michael Broxton, a research scientist in the Intelligent Robotics Group at Ames. “The collaborative relationship between NASA and Microsoft Research was instrumental for creating the software that brings these new Mars images into people’s hands, classrooms and living rooms.”

Click here to learn more and to download the WorldWide Telescope.

Source: JPL

Posted on by Nancy Atkinson

Dying Star or Beautiful Bird?

Hubble image of IRAS 19475+3119. Credit: ESA/Hubble and NASA.

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What a gorgeous new Hubble image! At first glance this object looks like a beautiful, giant, translucent bird. But it is actually star shedding its outer atmosphere. The cloud around this bright star is called IRAS 19475+3119. It lies in the constellation of Cygnus (the Swan) about 15, 000 light-years from Earth in the plane of our Milky Way galaxy.

From the ESA Hubble website:

As stars similar to the Sun age they swell into red giant stars and when this phase ends they start to shed their atmospheres into space. The surroundings become rich in dust and the star is still relatively cool. At this point the cloud shines by reflecting the brilliant light of the central star and the warm dust gives off lots of infrared radiation. It was this infrared radiation that was detected by the IRAS satellite in 1983 and brought the object to the attention of astronomers. Jets from the star may create strange hollow lobes, and in the case of IRAS 19475+3119 two such features appear at different angles. These curious objects are rare and short-lived.

As the star continues to shed material the hotter core is gradually revealed. The intense ultraviolet radiation causes the surrounding gas to glow brilliantly and a planetary nebula is born. The objects that come before planetary nebulae, such as IRAS 19475+3119, are known as preplanetary nebulae, or protoplanetary nebulae. They have nothing to do with planets — the name planetary nebula arose as they looked rather like the outer planets Uranus and Neptune when seen through small telescopes.

This image was created from images taken using the High Resolution Channel of the Hubble Space Telescope’s Advanced Camera for Surveys. The red light was captured through a filter letting through yellow and red light (F606W) and the blue was recorded through a standard blue filter (F435W). The green layer of the image was created by combining the blue and red images. The total exposure times were 24 s and 245 s for red and blue respectively. The field of view is about twenty arcseconds across.

Source: ESA Hubble

Posted on by Nancy Atkinson

Searching for the Elusive Type Ia Supernovae Progenitors

This Hubble image reveals the gigantic Pinwheel Galaxy (M101), one of the best known examples of "grand design spirals," and its supergiant star-forming regions in unprecedented detail. Astronomers have searched galaxies like this in a hunt for the progenitors of Type Ia supernovae, but their search has turned up mostly empty-handed. Credit: NASA/ESA
This Hubble image reveals the gigantic Pinwheel Galaxy (M101), one of the best known examples of "grand design spirals". Credit: NASA/ESA

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Astronomers have Type Ia supernovae pretty well figured out. The way these exploding stars brighten and then dim are so predictable that they have been used to measure the universe’s expansion. This reliability led to the discovery that our universe was not only expanding but accelerating, which in turn led to the discovery of dark energy. There’s just one minor detail: nobody knows for sure what causes a supernova.

“The question of what causes a Type Ia supernova is one of the great unsolved mysteries in astronomy,” says Rosanne Di Stefano of the Harvard-Smithsonian Center for Astrophysics.

Astronomers are sure that for a Type Ia supernova, the energy for the explosion comes from the run-away fusion of carbon and oxygen in the core of a white dwarf. To detonate, the white dwarf must gain mass until it reaches a tipping point and can no longer support itself.

But how does a white dwarf get bigger? There are two leading scenarios for what leads a stable white dwarf to go ka-boom, and both include a companion star. In the first possibility, a white dwarf swallows gas blowing from a neighboring giant star. In the second possibility, two white dwarfs collide and merge. To establish which option is correct (or at least more common), astronomers look for evidence of these binary systems.

In this negative image of the Pinwheel Galaxy (M101), red squares mark the positions of 'super-soft' X-ray sources. The Pinwheel should contain hundreds of accreting white dwarfs on which nuclear fusion is occurring, which should produce prodigious X-rays. Yet we only detect a few dozen super-soft X-ray sources. This means that we must devise new methods to search for the elusive progenitors of Type Ia supernovae. Credit: R. Di Stefano (CfA)

To find evidence of the first scenario, astronomers looked for accreting white dwarfs by seeking out so- called “super-soft” X-rays, which are produced when gas hitting the star’s surface undergoes nuclear fusion. Given the average rate of supernovae, a typical galaxy should contain hundreds of this type of X-ray sources. However, they are few and far between.

This led astronomers to believe that perhaps the merger scenario was the source of Type Ia supernovae, at least in many galaxies. That conclusion relies on the assumption that accreting white dwarfs will appear as super-soft X-ray sources when the incoming matter experiences nuclear fusion.

But a new paper by Di Stefano and her colleagues argues that the data do not support this hypothesis. The paper argues that a merger-induced supernova would also be preceded by an epoch during which a white dwarf accretes matter that should undergo nuclear fusion. White dwarfs are produced when stars age, and different stars age at different rates. Any close double white-dwarf system will pass through a phase in which the first-formed white dwarf gains and burns matter from its slower-aging companion. If these white dwarfs produce X-rays, then we should find roughly a hundred times as many super-soft X-ray sources as we do.

This means that super-soft X-rays aren’t providing evidence for either scenarios – an accretion-driven explosion and a merger-driven explosion – since they both involve accretion and fusion at some point The alternative proposed by Di Stefano is that the white dwarfs are not luminous at X-ray wavelengths for long stretches of time. Perhaps material surrounding a white dwarf can absorb X-rays, or accreting white dwarfs might emit most of their energy at other wavelengths.

If this is the correct explanation, says Di Stefano, “we must devise new methods to search for the elusive progenitors of Type Ia supernovae.”

Read Di Stefano’s paper in The Astrophysical Journal.

Source: CfA

Posted on by Nancy Atkinson

Rosetta Meets Asteroid Lutetia

Lutetia at closest approach. Image credit: ESA 2010 MPS for OSIRIS Team MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA

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Over the weekend, the Rosetta spacecraft flew by asteroid Lutetia, returning the first close up images of this battered, cratered body. By all accounts, the flyby was a spectacular success with Rosetta performing faultlessly. Closest approach took place at 16:10 GMT on July 10, at a distance of 3,162 km (1964 miles). The images show that Lutetia has been on the receiving end of many impacts during its 4.5 billion years of existence. As Rosetta drew close, a giant bowl-shaped depression stretching across much of the asteroid rotated into view. The images confirm that Lutetia is an elongated body, with its longest side around 130 km (80 miles).

“I think this is a very old object. Tonight we have seen a remnant of the Solar System’s creation,” said Holger Sierks, principal investigator for the spacecraft’s OSIRIS instrument, which combines a wide angle and a narrow angle camera. At closest approach, details down to a scale of 60 meters (see below) can be seen over the entire surface of Lutetia.

At a distance of 36,000 kilometers (22,369 miles) the OSIRIS Narrow Angle Camera (NAC) took this image catching the planet Saturn in the background. Image credit: ESA 2010 MPS for OSIRIS Team MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA

Rosetta raced past the asteroid at 15 km/s completing the flyby in just a minute. But the cameras and other instruments had been working for hours and in some cases days beforehand, and will continue afterwards. Shortly after closest approach, Rosetta began transmitting data to Earth for processing, and the Rosetta team will surely release more details in the coming days and weeks.

In the meantime, enjoy this wonderful poem composed by space poet laureate Stu Atkinson.

Lutetia in the Light

For all these years you were merely
A smear of light through our telescopes
On the clearest, coldest night; a hint
Of a glint, just a few pixels wide
On even your most perfectly-framed portraits.
But now, now we see you!
Swimming out of the dark – a great
Stone shark, your star-tanned skin pitted
And pocked, scarred after aeons of drifting
Silently through the endless ocean of space.
Here on Earth our faces lit up as we saw
You clearly for the first time; eyes wide
With wonder we traced the strangely familiar
Grooves raked across your sides,
Wondering if Rosetta had doubled back to Mars
And raced past Phobos by mistake –

Then you were gone, falling back into the black,
Not to be seen by human eyes again for a thousand
Blue Moons or more. But we know you now,
We know you; you’ll never be just a speck of light again.

—Stuart Atkinson

Zoom in on a possible landslide and boulders at the highest resolution. Image credit: ESA 2010 MPS for OSIRIS Team MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA

Sources: ESA, JPL, Rosetta Blog

Posted on by Tammy Plotner

Bright Outburst of QZ Virginis In Progress…


According to AAVSO Special Notice #212: “Hiroshi Matsuyama (MTH), Kanimbla, Queensland, Australia, reports and Rod Stubbings (SRX), Tetoora Road, Victoria, Australia, confirms that the SU UMa-type dwarf nova QZ Vir (formerly called T Leo) is in outburst, and possibly in superoutburst.”

Matsuyama reported it at visual magnitude 10.4 on July 9.409 UT (JD 2455386.909), and Stubbings at visual magnitude 10.0 on July 11.384 (JD 2455388.884).

According to observations in the AAVSO International Database, the last regular outburst of QZ Vir, which is 16th magnitude at quiescence, occurred 4 July 2009 (JD 2455017, magnitude 10.6, Matsuyama), when it reached visual magnitude 10.3 and faded to 15th magnitude by 9 July (2455022). The last superoutburst (see AAVSO Special Notice #144) occurred between 19 January 2009 (JD 2454851, magnitude <14.0, Stubbings) and 21 January 2009 (JD 2454853, 10.97V, R. Diethelm, Rodersdorf, Switzerland), when it reached magnitude 10.0 and returned to 16th magnitude by 1 March 2009 (2454862). If it is a superoutburst, superhumps will develop. All observations, including both visual estimates and CCD time-series photometry, are strongly encouraged at this time. Coordinates: RA 11:38:26.80 Dec +03:22:07.0 Many thanks for your valuable observing efforts and observations! This AAVSO Special Notice was prepared by Elizabeth O. Waagen.

Posted on by Steve Nerlich

Astronomy Without A Telescope – Coloring In The Oort Cloud

A very distant and very red Sedna. Credit: NASA, JPL, Caltech.

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It’s possible that if we do eventually observe the hypothetical objects that make up the hypothetical Oort cloud, they will all be a deep red color. This red coloring will probably be a mix of ices, richly laced with organic compounds – and may represent remnants of the primordial material from which the solar system was formed.

Furthermore, the wide range of colors found across different classes of trans-Neptunian objects may help to determine their origins.

The current observable classes of trans-Neptunian objects includes Pluto and similar objects called plutinos, which are caught in a 2:3 orbital resonance with Neptune towards the inner edge of the Kuiper belt. There are other Kuiper belt objects caught in a range of different resonant orbital ratios, including two-tinos – which are caught in a 1:2 resonance with Neptune – and which are found towards the outer edge of the Kuiper belt.

Otherwise, the majority of Kuiper belt objects (KBOs) are cubewanos (named after the first one discovered called QB1), which are also known as ‘classical’ KBOs. These are not obviously in orbital resonance with Neptune and their solar orbits are relatively circular and well outside Neptune’s orbit. There are two fairly distinct populations of cubewanos – those which have little inclination and those which are tilted more than 12 degrees away from the mean orbital plane of the solar system.

Beyond the Kuiper belt is the scattered disk – which contains objects with very eccentric elliptical orbits. So, although it may take hundreds of years for them to get there, the perihelions of many of these objects’ orbits are much closer to the Sun – suggesting this region is the main source of short period comets.

The trans-Neptunian landscape. Classical Kuiper belt objects have relatively circular orbits that never stray within the orbit of Neptune (yellow circle) - while plutinos and scattered disk objects have eccentric orbits that may. Classical objects with low inclinations (see ecliptic view) tend to have the deepest red coloration. Objects with higher inclination - and those with eccentric solar orbits which take them closer to the Sun - appear faded.

Now, there are an awful lot of trans-Neptunian objects out there and not all of them have been observed in detail, but surveys to date suggest the following trends:

  • Cubewanos with little inclination or eccentricity are a deep red color; and
  • Plutinos, scattered disk objects and highly inclined cubewanos are much less red.

Beyond the scattered disk are detached objects, that are clearly detached from the influence of the major planets. The best known example is Sedna – which is… yep, deep red (or ultra-red as the boffins prefer to say).

Sedna and other extreme outer trans-Neptunian objects are sometimes speculatively referred to as inner Oort cloud objects. So if we are willingly to assume that a few meager data points are representative of a wider (and hypothetical) population of Oort cloud objects – then maybe, like Sedna, they are all a deep red color.

And, looking back the other way, the ‘much less red’ color of highly inclined and highly eccentric trans-Neptunian objects is consistent with the color of comets, Centaurs (comets yet to be) and damocloids (comets that once were).

On this basis, it’s tempting to suggest that deep red is the color of primordial solar system material, but it’s a color that fades when exposed to moderate sunlight – something that seems to happen to objects that stray further inward than Neptune’s orbit. So maybe all those faded objects with inclined orbits used to exist much nearer to the Sun, but were flung outward during the early planetary migration maneuvers of the gas giants.

And the primordial red stuff? Maybe it’s frozen tholins – nitrogen-rich organic compounds produced by the irradiation of nitrogen and methane. And if this primordial red stuff has never been irradiated by our Sun, maybe it’s a remnant of the glowing dust cloud that was once our Sun’s stellar nursery.

Ah, what stories we can weave with scant data.

Further reading: Sheppard, S.S. The colors of extreme outer solar system objects.

Posted on by Tammy Plotner

Weekend SkyWatcher’s Forecast: July 9-11, 2010

Greetings, Fellow SkyWatchers! Is it hot enough for you where you live? Not if you’re in the southern hemisphere… But this weekend the southern hemisphere is the place to be if you’re interested in catching a total solar eclipse! If you can’t travel that close, then let’s travel far, far away as we take a look at the season’s globular clusters… from easy to challenging! Be sure to keep an eye on Saturn and Mars as they draw closer together and look for bright Jupiter in the morning skies! Whenever you’re ready? Grab your optics and I’ll see you in the backyard…

July 9, 2010 – On this date in 1979, Voyager 2 quietly made its closest approach to Jupiter. How about if we take a close approach before dawn as well? Enjoy the waltz of the Galileans and all the fine details! If you enjoy watching the planets swim against the night sky, then be sure to keep an eye on the early evening visage of Saturn as Mars “back strokes” its way towards the Ring King!

Tonight let’s head on out toward two more close objects that appear differently from the rest (and each other)—same-field binocular pair M10 and M12. Located about half a fist-width west of Beta Ophiuchi, M12 (RA 16 47 14 Dec –01 56 52) is the northern most of this pair. Easily seen as two hazy round spots in binoculars, let’s go to the telescope to find out what makes M12 tick.


Since this large globular is much more loosely concentrated, smaller scopes will begin to resolve individual stars from this 24,000-light-year-distant Class IX cluster. Note that there is a slight concentration toward the core region, but for the most part the cluster appears fairly even. Large instruments will resolve out individual chains and knots of stars.

Now let’s drop about 3.5 degrees southeast and check out Class VII M10 (RA 16 57 08 Dec –04 05 57). What a difference in structure! Although they seem to be close together and similar in size, the pair is actually separated by some 2,000 light-years. M10 is a much more concentrated globular, showing a brighter core region to even the most modest of instruments. This compression of stars is what differentiates one type of globular cluster from another and is the basis of their classification. M10 appears brighter, not because of this compression but because it is about 2,000 light-years closer than M12.

July 10, 2010 – Today we celebrate the 1832 birth on this date of Alvan Graham Clark. An astronomer himself, Clark was also a member of a famous American family of telescope makers. He helped to create the largest refractor in the world—the lenses for the 40″ Yerkes Telescope. Perhaps the stress of worrying for their safety took its toll on Alvan, for he died shortly after their first use. Tonight let’s honor Clark’s work by studying a globular cluster suitable for all optics, M4. All you have to know is Antares!

Just slightly more than a degree west (RA 16 23 35 Dec –26 31 31), this major 5th magnitude Class IX globular cluster can even be spotted unaided from a dark location. In 1746 Philippe Loys de Cheseaux happened upon this 7,200-light-year-distant beauty, one of the nearest to us. It was also included in Lacaille’s catalog as object I.9 and in Messier’s in 1764. Much to Charles’s credit, he was the first to resolve it!


As one of the loosest, or most ‘‘open,’’ globular clusters, M4 would be tremendous if we were not looking at it through a heavy cloud of interstellar dust. To binoculars, it is easy to pick out a very round, diffuse patch, yet it will begin to resolve with even a small telescope. Large telescopes will also easily see a central ‘‘bar’’ of stellar concentration across M4’s core region, which was first noted by Herschel. As an object of scientific study, in 1987, the first millisecond pulsar was discovered within M4, which turned out to be ten times faster than the Crab Nebula pulsar. Photographed by the Hubble Space Telescope in 1995, M4 was found to contain white dwarf stars—the oldest in our galaxy—with a planet orbiting one of them! A little more than twice the size of Jupiter, this planet is believed to be as old as the cluster itself. At 13 billion years, it would be three times the age of the Solar System!

July 11, 2010 – Today marks the 1732 birth on this date of Joseph Jerome Le Francais de Lalande, who determined the Moon’s parallax and published a comprehensive star catalog in 1801. While we might not be determining the Moon’s parallax against the background stars, we’re certainly going to see its effects against the background Sun! Right now the southern hemisphere is the place to be if you’re interested in catching a total solar eclipse – but this eclipse isn’t going to be an easy one to observe unless you’re on the water.


Starting roughly 2000 kilometers northeast of New Zealand at 18:15 UT, totality will begin at local sunrise over the ocean. Minutes later the shadow pass will actually cross land as it encounters the island of Mangaia for about 3 minutes total time. Totality will brush by Tahiti, encompass the uninhabited atolls of the Tuamotu Archipelago and slide its way across the mysterious Easter Island. The Moon’s shadow will take once again to the water for another 3700 kilometers where it will reach its end at the very southernmost tip of South America. For those of you who have the great fortune to eclipse chase? We wish you the very best of skies and luck!

For hard-core observers, tonight’s globular cluster study will require at least a mid-aperture telescope, because we’re staying up a bit later to go for a same-low-power-field pair—NGC 6522 (RA 18 03 34 Dec –30 02 02) and NGC 6528 (RA 18 04 49 Dec –30 03 20). You will find them easily at low power just a breath northwest of Gamma Sagittarii, better known as Al Nasl, the tip of the ‘‘teapot’s’’ spout. Once located, switch to higher power to keep the light of Gamma out of the field, and let’s do some study.


The brighter, and slightly larger, of the pair to the northeast is Class VI NGC 6522. Note its level of concentration compared to the Class V NGC 6528. Both are located around 2,000 light years away from the galactic center and are seen through a very special area of the sky known as ‘‘Baade’s Window’’—one of the few areas toward our galaxy’s core region not obscured by dark dust.

Although each is similar in concentration, distance, etc., NGC 6522 has a slight amount of resolution toward its edges, while NGC 6528 appears more random. Although both NGC 6522 and NGC 6528 were discovered by Herschel on July 24, 1784, and both are the same distance from the galactic core, they are very different. NGC 6522 has an intermediate metallicity. At its core, the red giants have been depleted, or stripped tidally by evolving into blue stragglers. It is possible that core collapse has already occurred. NGC 6528, however, contains one of the highest metal contents of any known globular cluster collected in its bulging core!

Until next time? Keep reaching for the stars!

This week’s awesome images are: M10, M12, M4, NGC 6522 and NGC 6528 from Palomar Observatory, courtesy of Caltech. Alvan Clark historical image and eclipse information courtesy of NASA. We thank you so much!

Posted on by Nancy Atkinson

Watch Live Webcast of Rosetta Flyby of Asteroid Lutetia July 10

Rosetta captured this image of asteroid (21) Lutetia on July 9, 2010, at 01:00 UTC, when the spacecraft was still about two million kilometers (and 36 hours) from the asteroid. Credit: ESA 2010 MPS for OSIRIS Team

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On July 10, ESA’s Rosetta spacecraft will fly past 21 Lutetia, the largest asteroid ever visited by a satellite. After weeks of maneuvers and optical observations, Rosetta is perfectly lined up to skim by the asteroid only 3,162 km (2,000 miles) away. ESA is hosting a live webcast at 16:00 GMT on July 10. Below is an embedded feed that will go live once the webcast begins.

For more information and a complete timeline of events, check out this ESA web page.

Watch live streaming video from eurospaceagency at livestream.com

Rosetta is expected to pass Lutetia at a relative speed of 54,000 km/hr. All this takes place 454 million km from Earth. Lutetia is a major scientific target of Rosetta’s mission, so most of the orbiter and lander instruments will be on for flyby, studying the asteroid’s surface, dust environment, exosphere, magnetic field, mass and density.

Rosetta is on its way to a 2014 rendezvous with comet 67P/Churyumov-Gerasimenko.

Posted on by Nancy Atkinson

Mini Moons Are Buzzing Through Saturn’s Rings

Using images obtained by NASA's Cassini mission, astronomers followed several of what are likely to be dozens of small moons orbiting within the outer edge of Saturn's A ring -- the outermost of the planet's large, dense rings -- from 2005 to 2009.

Scientists for NASA’s Cassini mission noticed some weird-looking propeller-like shapes in the outer edge of Saturn’s A ring. What could be creating these unusual contours? A closer look revealed they were being formed by dozens of moving moonlets. Normally, these kilometer-sized moons would have been almost impossible to see, since they are embedded within the rings. “However, their presence is betrayed by the large tell-tale ‘propeller’ structures they generate in the ring material on either side of them,” said Carolyn Porco, leader of the Cassini imaging team, and co-author on a new paper on these propeller moons. In an email, Porco said similar features had been seen earlier in other locations in Saturn’s rings, but were “much smaller, harder to see, and so numerous that there was no hope of following any one of them. The new propellers, and the moonlets that create them, are some ten times larger and much easier to identify and follow from image to image and year to year.”

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The team said the ability to watch as the embedded moons’ orbits evolve over time could give scientists valuable new clues about how planets form and grow around stars in young solar systems.

“What is outstanding about these new findings is the insight they ultimately will provide into the early stages of solar system formation,” said Porco, “when growing planets become large enough to open gaps in the ring material around them and ultimately truncate their own growth.”

The scientists have tracked eleven of these moons since 2006. Most are between one and several kilometers in diameter, too small to be imaged directly by Cassini’s cameras, but are only distinguishable by the unique double-armed propeller features.

The area in the middle of Saturn’s outermost dense A ring is now known as the “propeller belts,” and the new moonlets have been given appropriate names.

“You may find it amusing that these large propellers have unofficially been named after famous aviators,” Porco said. “Those flight enthusiasts among you will recognize Bleriot, Earhart, Santos-Dumont, and others.”

Cassini caught sight of Blériot (named after a French aviator) more than 100 times, allowing the researchers to map its path in detail. The propeller shape it created is several thousand kilometers long, or half the distance across the continental United States.

“You would expect any object that’s just orbiting Saturn on its own should stay in a constant path,” said lead author Matthew Tiscareno from Cornell University. “What we actually see is that the orbits are changing.”

The most likely explanation, he said, is that the moons are actually interacting with the disk: exchanging angular momentum with the ring particles around them either through gravity or by direct collisions.

Still, other explanations, like resonant interactions with more distant moons, have not been ruled out as causes.

Scientists will be keeping an eye on these wandering little moons in order to figure out if the disk itself is driving the changes, similar to the interactions that occur in young solar systems. If it is, Tiscareno said, this would be the first time such a measurement has been made directly.

Read the team’s paper.

More images at CICLOPS

Sources: NASA, Cornell, Porco email

Posted on by Nancy Atkinson

Are You Keeping an Eye on SDO Keeping an Eye on the Sun?

Have you been checking out the Solar Dynamics Observatory website and seeing all the amazing, high resolution images of our closest star? If not, you should. Above is a great new video of SDO’s capabilities and latest images. If you want to see what the Sun looks like right now, go to SDO’s homepage. And here’s a link to the SDO image browser where you can see the different images in different wavelengths from the AIA (Atmospheric Imaging Assembly) and HMI (Helioseismic and Magnetic Imager). If you choose the date range option, you can see a “movie” of the Sun’s activity. For example, check out the enormous coronal hole in the northern hemisphere seen last week in AIA 193 (date range 6/28 to 7/3), allow all the images to download and then press “Play.” Completely awesome. The SDO website should be part of your daily internet routine!