A fish-eye view of Titan's surface from the European Space Agency's Huygens lander in January 2005. Credit: ESA/NASA/JPL/University of Arizona
What’s in all that browny orangey stuff in the atmosphere around Titan? It’s a question that scientists have been trying to answer concerning Saturn’s moon for decades (Carl Sagan was among them). That’s because it’s hard to reverse-engineer the recipe.
There are hundreds of thousands of hydrocarbons (hydrogen and carbon molecules) that could form the compounds in the atmosphere along with nitriles (nitrogen-abundant chemicals). But scientists are hoping that their new recipe gets a bit closer to understanding how the atmosphere works.
The researchers put gases inside of a chamber and monitored their reactions, starting with nitrogen and methane — the gases that are the most common in Titan’s atmosphere. Then they included benzene — which the Cassini spacecraft has detected in the atmosphere — along with close chemical relatives.
Titan’s surface is almost completely hidden from view by its thick orange “smog” (NASA/JPL-Caltech/SSI. Composite by J. Major)
In the end, it seemed the best third ingredient was choosing an “aromatic”, a sort of hydrocarbon, that includes nitrogen. That’s because the scientists saw that the spectrum of this gas appeared to be similar to what was spotted by Cassini.
“This is the closest anyone has come, to our knowledge, to recreating with lab experiments this particular feature seen in the Cassini data,” stated lead author Joshua Sebree, a former postdoctoral fellow at the NASA Goddard Space Flight Center who is now an assistant professor at the University of Northern Iowa in Cedar Falls.
Scientists say the recipe still needs some modifications, but this is a good start. The research is available in the journal Icarus.
The May 15th, 2014 occultation of Saturn by the Moon as seen from Australia. (Credit: Byuki/Silveryway).
Some terms in astronomy definitely have a PR problem, and are perhaps due for an overhaul. One such awkward term is occultation, which simply means that one celestial body is passing in front of another from an observer’s vantage point, nothing more, and nothing less. I know, the word ‘occult’ is in there, raising many a non-astronomically minded eyebrow and evoking astronomy’s hoary astrological past. You can even use it as a verb in this sense, as in to ‘occult’ one body with another. A planet or asteroid can occult a star, your cat can occult your laptop’s screen, and the Moon can occult a star or planet, as occurs on Tuesday, June 10th when the waxing gibbous Moon occults the planet Saturn for observers across the southern Indian Ocean region.
The occultation footprint for the June 10th event. The solid lines denote where the occultation occurs after sunset. Created using Occult 4.0.
Of course, most of us will see a near miss worldwide. This is parallax in motion, as differing vantage points on the surface of the planet Earth see the Moon against a different starry background.
And we’re currently in the midst of a cycle of occultations of the planet Saturn in 2014, as the Moon occults it 11 times this year, nearly once for every lunation. The Moon actually occults planets 22 times in 2014, 24 if you count the occultations of 1 Ceres and 4 Vesta on September 28th, with Saturn getting covered by the Moon once again on the same date! Saturn tops the list in the number of times it’s occulted by the Moon this year, as it’s the slowest moving of the planets and fails to hustle out of the Moon’s way until November, after which a series of occultations of the ringed planet won’t resume again until December 9th, 2018.
Four selected views of the occultation/conjunction of the Moon and Saturn on June 10th worldwide. (Credit: Stellarium).
The shadow footprint of the June 10th occultation just makes landfall over southwestern Australia near Perth, a slice of Antarctica, and a scattering of southern Indian Ocean islands and the southern tip of South Africa in and around Cape Town. Note that the phase of the Moon is changing by about 30 degrees of ecliptic longitude as well during each successive occultation of Saturn. Next week’s event occurs as the Moon is at a 93% waxing gibbous illuminated phase this month and soon will occur when the Moon is a crescent. What’s especially interesting is the dark limb of the Moon is always the leading edge during waxing phases; this means that any stars or planets in its way get hidden (or ingress) under its shady nighttime edge.
Looking to the southeast from latitude 30 degrees north from the US east coast at 10 PM EDT. Created using Starry Night Education software.
Central conjunction for Saturn and the Moon actually occurs at around 19:00 Universal Time on June 10th. The Moon rises at around 6:00 PM local on this date, and North American observers will see Saturn 4 degrees from the limb of the Moon and at an elevation of 28 degrees above the horizon at dusk. Unfortunately, the best occultation of Saturn by the Moon for North America in 2014 occurs in the daytime on August 31st, though you can indeed catch Saturn in the broad daylight through a telescope with good sky transparency if you know exactly where to look for it… a nearby daytime Moon certainly helps!
Unlike stellar occultations, blockages of planets by the Moon are leisurely events, and lend themselves to some pretty amazing video sequences. You can actually get a sense of the motion of the Moon as you watch it slowly cover the planet’s disk, in real time. It might also be fun to catch the occultation of Saturn’s brightest moon, +9th magnitude Titan. Hey, a moon occulting a moon, a sort of cosmic irony…
Saturn spends all of 2014 in the astronomical constellation of Libra. The Moon moves on to Full on Friday the 13th — triskaidekaphobics take note — at 4:13 UT/00:13 AM EDT. This is the closest Full Moon to the northward solstice which occurs on June 21st at 10:51 UT/6:51 AM EDT, meaning that while the Sun rides high in the sky during the day, the rising Full Moon transits low to the south at night. In the southern hemisphere, the reverse is true in June.
The June Full Moon is also known as per ye ole Farmer’s Almanac as the Strawberry or Rose Moon.
So there you have it, occultations were evoked no less than 21 times in the writing of this post. We need a modern, hip, internet ready meme to supplant the term occultation… y’know, like “ring of fire” for and annular eclipse or minimoon for an apogee moon, etc… blockage? Covering? Enveloping? Let us know what you think!
Several images of an aurora on Saturn's north pole taken in April and May 2013 by the Hubble Space Telescope. Credit: NASA/ESA, Acknowledgement: J. Nichols (University of Leicester)
It’s amazing to see what some flashes of light can tell us. New images the Hubble Space Telescope took of Saturn not only reveal auroras dancing in the north pole, but also reveal some interesting things about the giant planet’s magnetic field.
“It appears that when particles from the Sun hit Saturn, the magnetotail collapses and later reconfigures itself, an event that is reflected in the dynamics of its auroras,” the European Space Agency wrote in a description of the image.
“Saturn was caught during a very dynamic light show – some of the bursts of light seen shooting around Saturn’s polar regions traveled more than three times faster than the speed of the gas giant’s roughly 10-hour rotation period.”
And for those readers that remember the music video from Saturn that the Cassini spacecraft took — also of auroras — ESA said this new research complements what the other spacecraft did, too.
The research has been accepted for publication in Geophysical Research Letters.
Saturn heading behind the Moon on May 14, 2014. Credit and copyright: Silveryway on Flickr.
Observers in Australia and New Zealand had a special treat this week: watching Saturn disappear behind the Moon during an event called an occultation. (You can read all the details of how and why this happens here in our preview article.) Catching an event like this with a camera is tricky… the bright Moon can wash out the comparatively tiny (from our vantage point) planet Saturn. But here, several astrophotographers had success. Above is a nice view from Silveryway on Flickr.
An animated gif of the occulation of Saturn by the Moon on May 14, 2014. Credit and copyright: Ian Musgrave.
Ian Musgrave from Australia used a 4″ Newtonian telescope, with a “Point and Shoot” Canon IXUS attached with inifinty to infinity focussing, 3xZoom, and a 25mm eye piece. You can see his entire set of images on his website here.
Widefield view of the occultation of Saturn on May 14, 2014. Credit and copyright: Ian Musgrave.
Peter Lake, also from Australia not only took images of the event, but also did a live Hangout on G+.
“Live hangouts and driving a telescope live is a tricky business,” Peter wrote on his website. “I lost focus playing around trying to improve the image due to the thin cloud.” He added that the night sky wasn’t ideal that evening. “The full moon was shining through thin clouds, washing out a bit of the detail.”
Saturn getting ready to head behind the Moon. Credit and copyright: Peter Lake.
You can watch a replay of Peter’s Hangout below:
Saturn and the Moon diffusion. The clouds drifted across the sky, Saturn and the Moon shone bright, the view from the UK. Credit and copyright: Sarah and Simon Fisher.
Sarah and Simon Fisher from the UK captured this “diffused” view of Saturn close the Moon on the evening of May 13, 2014.
Want to get your astrophoto featured on Universe Today? Join our Flickr group or send us your images by email (this means you’re giving us permission to post them). Please explain what’s in the picture, when you took it, the equipment you used, etc.
Simulation of the moon closing in on Saturn just prior to occultation. Credit: Gianluca Masi using SkyX software
Funny thing. Skywatchers are often just as excited to watch a celestial object disappear as we are to see it make an appearance. Early Wednesday morning (May 14) the Full Flower Moon will slip in front of Saturn, covering it from view for about an hour for observers in Australia and New Zealand. If you don’t live where the dingoes roam, no worries. You can watch it online.And no matter where you are on the planet, the big moon will accompany the ringed planet across the sky this Tues. night-Weds. morning.
Moon-Saturn occultation from Perth, Australia Feb. 22, 2014 captured by Colin Legg
Occultations of stars happen swiftly. The moon’s limb meets the pinpoint star and bam! it’s gone in a flash. But Saturn is an extended object and the moon needs time to cover one end of the rings to the other. Planetary occultations afford the opportunity to remove yourself from planet Earth and watch a planet ‘set’ and ‘rise’ over the alien lunar landscape. Like seeing a Chesley Bonestell painting in the flesh.
Saturn and the moon Tuesday night (May 13) just before midnight as viewed from the U.S. Stellarium
As the moon approaches Saturn, the planet first touches the lunar limb and then appears to ‘set’ as it’s covered by degrees. About an hour later, the planet ‘rises’ from the opposite limb. Planetary occultations are infrequent and always worth the effort to see.
Seen from the northern hemisphere and equatorial regions, the nearly full moon will appear several degrees to the right or west of Saturn tomorrow night (May 13). As the night deepens and the moon rolls westward, the two grow closer and closer. They’ll be only a degree apart (two full moon diameters) during Wednesday morning twilight seen from the West Coast. Northern hemisphere viewers will notice that the moon slides to the south of the planet overnight.
Map showing the region where the occultation of Saturn will be visible. Click to get times of Saturn’s disappearance and reappearance for individual cities. Times shown are UT or Universal Time. Add 9.5 hours for Australian Central Standard Time. Credit: IOTA
Skywatchers in Australia will see the moon cover Saturn during convenient early evening viewing hours May 14:
* 8:09 p.m. local time from Adelaide
* 9:05 p.m. Brisbane
* 8:50 p.m. Melbourne
* 8:53 p.m. Canberra
* 8:56 p.m. from Sydney (More times and a map – click HERE)
Before the occultation, Saturn will shine close to the moon’s upper right and might be tricky to see with the naked eye because of glare.
Binoculars will easily reveal the planet, but a telescope is the instrument of choice. Even a small scope magnifying at least 30x will show Saturn and its rings hovering above the bright edge of the moon. Stick around. About an hour later, Saturn will re-emerge along the moon’s lower left limb.
Saturn and its moons Tuesday night May 13 around 10 p.m. CDT. Titan’s the brightest and easiest moon to see at magnitude +8.5. Iapetus ranges from magnitude +10 when it’s west of Saturn and we see its bright hemisphere to magnitude +12 when it’s east of the planet. Created with Meridian software
Meanwhile, back in the western hemisphere, we’ll watch the nearly full Flower Moon make a close pass of the planet. If you’ve had difficulty finding the celestial ring bearer, you’ll have no problem Tuesday night. Take a look at Saturn’s wonderful system of rings in your telescope – they’re tipped nearly wide open this year. For even more fun, see how many moons you can spot. And don’t forget, you can watch it online courtesy of astrophysicist Gianluca Masi. His Virtual Telescope website will broadcast the occultation live starting at 10:15 Universal Time May 14 (6:15 a.m. EDT, 5:15 CDT, 4:15 MDT and 3:15 PDT).
Uranus as seen by Cassini on July 19, 2013 (NASA/JPL-Caltech/SSI)
When you hear the words “pale blue dot” you’re probably reminded of the famous quote by Carl Sagan inspired by an image of Earth as a soberingly tiny speck, as imaged by Voyager 1 on Feb. 14, 1990 from beyond the orbit of Pluto. But there’s another pale blue world in our Solar System: the ice giant Uranus, and its picture was captured much more recently by the Cassini spacecraft from orbit around Saturn on April 11, 2014.
Released today by the Cassini Imaging Team, the image above shows Uranus as a tiny blue orb shining far beyond the bright hazy bands of Saturn’s F ring.
“Do you relish the notion of being a Saturnian, and gazing out from the lofty heights of Saturn at the same planets we see here from the Earth?”
– Carolyn Porco, Cassini Imaging Team Leader
Uranus’ coloration is a result of methane high in its frigid atmosphere. According to the description on the CICLOPS site, “methane on Uranus — and its sapphire-colored sibling, Neptune — absorbs red wavelengths of incoming sunlight, but allows blue wavelengths to escape back into space, resulting in the predominantly bluish color seen here.”
This was also the first time Uranus had been imaged by the Cassini spacecraft, which has been in orbit around Saturn since 2004. In fact its ten-year orbital anniversary will come on July 1.
This image adds one more planet to the list of worlds captured on Camera by Cassini, which made headlines last fall when a glorious mosaic was released that featured a backlit Saturn in eclipse surrounded by its luminous rings, the specks of several of its moons, and the distant dots of Venus, Mars, and the Earth and Moon. Made from 141 separate exposures, the mosaic was captured on July 19, 2013 — known by many space aficionados as “the day the Earth smiled” as it was the first time the world’s population was alerted beforehand that its picture would be taken from over 900 million miles away.
Saturn — with its terrestrial spacecraft in tow — was about 28.6 AU away from Uranus when the image was acquired. That’s about 4.28 billion kilometers (2.66 billion miles). From that distance the glow of the 51,118-kilometer (31,763-mile) -wide Uranus is reduced to a mere few pixels (which required digital brightening by about 4.5x, as well.)
NASA's Curiosity Mars rover has caught the first image of asteroids taken from the surface of Mars. The image includes two asteroids, Ceres and Vesta. This version includes Mars' moon Deimos in a circular, exposure-adjusted inset and square insets at left from other observations the same night. Credit: NASA/JPL-Caltech/MSSS/Texas A&M
NASA’s Curiosity Mars rover has caught the first image of asteroids taken from the surface of Mars on April 20, 2014. The image includes two asteroids, Ceres and Vesta. This version includes Mars’ moon Deimos in a circular, exposure-adjusted inset and square insets at left from other observations the same night. Credit: NASA/JPL-Caltech/MSSS/Texas A&M
More night sky views and surface mosaics below[/caption]
The Curiosity rover has captured the first images of asteroids even taken by a Human probe from the alien surface of the Red Planet during night sky imaging.
And it’s not just one asteroid, but two asteroids caught in the same night time pointing on the Red Planet. Namely, asteroids Ceres and Vesta.
The stupendous image – seen above – was snapped by Curiosity’s high resolution Mastcam camera earlier this week on Sunday, April 20, 2014, Sol 606, whilst she was scanning about during daylight for her next drilling target at “The Kimberley” waypoint she pulled into at the start of this month.
Ceres and Vesta appear as streaks since the Mastcam image was taken as a 12 second time exposure.
“This imaging was part of an experiment checking the opacity of the atmosphere at night in Curiosity’s location on Mars, where water-ice clouds and hazes develop during this season,” said camera team member Mark Lemmon of Texas A&M University, College Station, in a statement.
“The two Martian moons were the main targets that night, but we chose a time when one of the moons was near Ceres and Vesta in the sky.”
View our “Kimberley” region photo mosiacs below to see exactly from where the six wheeled robot took the asteroid image shown above, while driving around the base of “Mount Remarkable”.
And those two asteroids are extra special because not only are they the two most massive objects in the Main asteroid belt between Mars and Jupiter, but they are also the destinations of another superlative NASA unmanned mission – Dawn.
Curiosity Mars rover captured this panoramic view of a butte called “Mount Remarkable” and surrounding outcrops at “The Kimberley ” waypoint on April 11, 2014, Sol 597. Colorized navcam photomosaic was stitched by Marco Di Lorenzo and Ken Kremer. Credit: NASA/JPL-Caltech/Marco Di Lorenzo/Ken Kremer – kenkremer.com
The exotic Dawn probe, propelled by a stream of ions, orbited Vesta for a year in 2011 and is now approaching Ceres for an exciting orbital mission in 2015.
Ceres, the largest asteroid, is about 590 miles (950 kilometers) in diameter. Vesta is the third-largest object in the main belt and measures about 350 miles (563 kilometers) wide.
And as if Curiosity’s mouthwatering and heavenly double asteroid gaze wasn’t already spectacular enough, the tinier of Mars’ moons, Deimos, was also caught in that same image.
A trio of star trails is also seen, again due to the 12 second time exposure time.
Furthermore, Mars largest moon Phobos as well as massive planets Jupiter and Saturn were also visible that same Martian evening, albeit in a different pointing.
These celestial objects are all combined in the composite image above.
“The background is detector noise, limiting what we can see to magnitude 6 or 7, much like normal human eyesight. The two asteroids and three stars would be visible to someone of normal eyesight standing on Mars. Specks are effects of cosmic rays striking the camera’s light detector,” says NASA.
An unannotated image is seen below.
NASA’s Curiosity Mars rover has caught the first image of asteroids taken from the surface of Mars. The image includes two asteroids, Ceres and Vesta. In this unannotated version of the 12-second-exposure image, the brightness of Deimos at lower right saturates the image, making the moon appear overly large. Credit: NASA/JPL-Caltech/MSSS/Texas A&M
Curiosity’s makers back on Earth are nowhere to be seen. But check out the Curiosity’s earlier photo below of the Earth and Moon from my prior article – here.
To date, Curiosity’s odometer totals 3.8 miles (6.1 kilometers) since landing inside Gale Crater on Mars in August 2012. She has taken over 143,000 images.
The sedimentary foothills of Mount Sharp, which reaches 3.4 miles (5.5 km) into the Martian sky, is the 1 ton robots ultimate destination inside Gale Crater because it holds caches of water altered minerals. Such minerals could possibly indicate locations that sustained potential Martian life forms, past or present, if they ever existed. Martian landscape with rows of curved rock outcrops at ‘Kimberly’ in the foreground and spectacular Mount Sharp on the horizon. NASA’s Curiosity Mars rover pulled into Kimberly waypoint dominated by layered rock outcrops as likely drilling site. This colorized navcam camera photomosaic was assembled from imagery taken on Sol 576 (Mar. 20, 2014). Credit: NASA/JPL-Caltech/Marco Di Lorenzo/Ken Kremer-kenkremer.com
Curiosity has some 4 kilometers to go to reach the base of Mount Sharp sometime later this year.
Stay tuned here for Ken’s continuing Curiosity, Opportunity, Chang’e-3, SpaceX, Orbital Sciences, LADEE, MAVEN, MOM, Mars and more planetary and human spaceflight news.
You are here! – As an Evening Star in the Martian Sky
This evening-sky view taken by NASA’s Mars rover Curiosity shows the Earth and Earth’s moon as seen on Jan. 31, 2014, or Sol 529 shortly after sunset at the Dingo Gap inside Gale Crater. Credit: NASA/JPL-Caltech/MSSS/TAMUMars rock rows and Mount Sharp. Martian landscape scene with rows of striated rocks in the foreground and Mount Sharp on the horizon. NASA’s Curiosity Mars rover paused mid drive at the Junda outcrop to snap the component images for this navcam camera photomosaic on Sol 548 (Feb. 19, 2014) and then continued traveling southwards towards mountain base. UHF Antenna at right. Credit: NASA/JPL-Caltech/Marco Di Lorenzo/Ken Kremer-kenkremer.com
Saturn as imaged from Aguadilla, Puerto Rico on April 15th. Credit: Efrain Morales.
Planet lovers can rejoice: one of the finest jewels of the solar system in returning to the evening night sky.
The planet Saturn reaches opposition next month on May 10th. This means that as the Sun sets to the west, Saturn will rise “opposite” to it in the east, remaining well positioned for observation in the early evening hours throughout the summer season. In fact, we’ll have four of the five naked eye planets above the horizon at once for our evening viewing pleasure in the month of May, as Jupiter also rides high to the west at sunset, Mars just passed opposition last month and Mercury reaches greatest eastern elongation on May 25th. Venus is the solitary holdout, spending a majority of 2014 in the dawn sky.
Saturn will shine at magnitude +0.3 this month and its disk spans an apparent 19,” or 44” if you take into account the apparent width of its rings. The rings are currently tipped open 22 degrees with respect to our line of sight. The ring opening is widening, and will reach a maximum of over 25 degrees in 2017 before the trend reverses. Anyone who remembers observing Saturn back in 2009 will recall that its rings were edge on to our view. This widening of Saturn’s rings also lends itself to a curious effect: although we’re in a cycle of oppositions that are getting farther away — Saturn is 12.5 million kilometres or 0.083 Astronomical Units (A.U.s) more distant in 2014 than it was during opposition last year as it’s headed towards aphelion in 2018 — its widening rings are actually making it appear a bit brighter.
The path of Saturn through the constellation Libra from April through October 2014. Created using Starry Night Education Software.
This year’s opposition will find Saturn in the astronomical constellation of Libra, where it’ll spend most of 2014. Oppositions of the ringed planet are set to continue to “head south” until 2018, and won’t occur north of the celestial equator again until 2026. I remember when oppositions of Saturn returned to the constellation Virgo a few years back — where I had first looked at it with my 60mm Jason refractor as a teenager — and realizing that I had now been into observational astronomy for roughly one “Saturnian year.”
The ancients had little knowledge of how unique Saturn was. The faintest and slowest moving of the classical planets, even Galileo knew that something was up when he turned his first primitive telescope towards it. His sketches depict Saturn as something similar to a double handled coffee cup, a testament to how poor his view really was. It wouldn’t be until Christiaan Huygens in 1655 that the true nature of Saturn’s rings was deduced as a flat and separate feature from the disk.
At opposition, the disk of the planet casts a shadow straight back from our point of view. This vantage slowly changes as the planet moves towards eastern quadrature on August 9th and we get a glimpse slightly off to one side of the planet. After opposition, the shadow of the disk can again be seen casting back onto the rings.
An outstanding IPhone 4S capture of Saturn on April 20th, 2014. Credit: Andrew Symes, @FailedProtostar.
Another interesting phenomenon to watch out for near opposition is known as the Seeliger effect. Also sometimes referred to as the “opposition surge,” this sudden brightening of the disk and rings is a subtle effect, as the globe of Saturn and all of those tiny little ice crystals reach 100% illumination. This effect can be noted to the naked eye on successive nights around opposition, and will get more prominent towards 2017. Coherent-backscattering of light has also been proposed as a possible explanation of this phenomenon. Perhaps a video sequence capturing this effect is in order for skilled astro-imagers in 2014.
Through a small telescope, the first feature that becomes apparent is Saturn’s glorious system of rings. Crank up the magnification, and you’ll note a dark groove in the ring system. This is the Cassini Division, first described by Giovanni Cassini in 1675.
Here’s a challenge we came across some years back: can you see the disk of Saturn through the Cassini Division? Right around opposition is a good time to attempt this unusual feat of visual athletics.
A sample simulation depicting the orientation of Saturn’s observable moons on the night of May 9th. Created using Starry Night Education software.
Saturn’s large moon Titan is an easy catch at magnitude +8 in a small telescope. Titan is the second largest moon in the solar system. Place it in a direct orbit about the Sun, and it would be considered a planet, no problem. 7 of Saturn’s 62 known moons are within reach of a small telescope. In addition to Titan, they are, with quoted magnitudes: Mimas (+13), Enceladus (+12), Tethys (+10), Rhea (+10), Dione (+11) and Iapetus. Iapetus is of special interest, as it brightens from +11.9 to magnitude +10.2 as it traces out its 79 day orbit. We always knew there was something unique about this moon, and NASA’s Cassini mission revealed the world to have two distinctly different hemispheres with vastly different albedos during its close 2007 flyby.
The close passage of the Full Moon near Saturn on May 14th. Created using Stellarium.
Also, be sure to check out Saturn on the night of May 14th — just 4 nights after opposition — as the Full Moon sits less than a degree south of the ringed planet. Can you see both in the same telescopic field of view? Can you nab Saturn next to the rising daytime Moon low to the horizon just before local sunset? The Moon will actually occult (pass in front of) Saturn for viewers based in Australia and New Zealand on the 14th. This is only one of 11 occultations — nearly one for each lunation — of Saturn by the Moon in 2014. Unfortunately, the best one for North America occurs in the daytime on August 31st, though it too may be observable telescopically.
The footprint of the May 14th occultation of Saturn by the Moon. Credit: Occult 4.0.
Finally, this evening apparition of the planet runs through northern hemisphere summer and fall until Saturn reaches solar conjunction on November 18th. So get those homemade planetcams out, send those pics in to Universe Today, and be sure to join in to the Virtual Star Party every Sunday Night… Saturn is sure to be featured!
A 750-mile (1,200-km) -long feature spotted on Saturn's A ring by Cassini on April 15, 2013
Congratulations! It’s a baby… moon? A bright clump spotted orbiting Saturn at the outermost edge of its A ring may be a brand new moon in the process of being born, according to research recently published in the journal Icarus.
“We have not seen anything like this before,” said Carl Murray of Queen Mary University in London, lead author of the paper. “We may be looking at the act of birth, where this object is just leaving the rings and heading off to be a moon in its own right.”
In images acquired with Cassini’s narrow-angle camera in 2013, a 1,200-kilometer-long, 10-kilometer-wide arc of icy material was observed traveling along the edge of the A ring. The arc is thought to be the result of gravitational perturbations caused by an as-yet unseen embedded object about a kilometer wide — possibly a miniature moon in the process of formation.
Cassini image of 179-km-wide Janus from April 2010. Janus’ gravity may have helped spur the formation of Peggy. (NASA/JPL-Caltech/SSI)
The half-mile-wide object has been unofficially named “Peggy,” after lead author Murray’s mother-in-law (whose 80th birthday it was on the day he was studying the Cassini NAC images.) Murray first announced the findings on Dec. 10, 2013 at the AGU 13 meeting in San Francisco.
According to the team’s paper, Peggy’s effects on the A ring has been visible to Cassini since May 2012.
Eventually Peggy may coalesce into a slightly larger moon and move outward, establishing its own orbital path around Saturn. This is how many of Saturn’s other moons are thought to have formed much further back in the planet’s history. Now, its rings having been depleted of moon-stuff, can only create tiny objects like Peggy.
“Witnessing the possible birth of a tiny moon is an exciting, unexpected event.”
– Linda Spilker, Cassini Project Scientist at JPL
While it is possible that the bright perturbation is the result of an object’s breakup rather than formation, researchers are still looking forward to finding out more about its evolution.
Raw image of Saturn with two moons acquired by Cassini on March 11, 2014 (NASA/JPL-Caltech/SSI)
On March 11, NASA’s Cassini spacecraft was acquiring some images of Saturn’s back-lit limb when two of its moons decided to make an entrance. Like stage hands in a darkened theatre the moons quickly passed across the scene, moving between Saturn and the spacecraft and, because of exposure time and spacecraft motion, getting a bit blurred in the process.
In the image above the silhouette of one moon can be seen at bottom right — Mimas, perhaps — while another’s crescent can be made out at upper left… possibly Enceladus. Very cool!
Watch an animation of the moons below:
Two of Saturn’s moons drift into the scene on March 11, 2014 (NASA/JPL-Caltech/SSI. Animation by Jason Major.)
While I admit I’m not 100% sure which moons these are, based on their apparent shapes, positions, and relative sizes I’d make my guess that these are 318-mile (511-km) -wide Enceladus and the 246-mile (395-km) -wide Mimas.
Possible location of icy spray, if Enceladus is in fact this moon’s real name
Cassini was 843,762 miles (1,357,903 km) from Saturn when the images were acquired. And, if the larger moon at left is Enceladus, I’m thinking south in these images is up based on the barely-perceptible presence of a lighter area along its top edge that could be icy spray from its southern geysers. (See enlarged detail at right.)
Saturn, of course, is on the right. A small segment of the bright arc of its backlit limb is what’s running diagonally down across the image.
These images have not yet been calibrated or cataloged by NASA or the Cassini team.
See the latest raw images from Cassini on JPL’s mission page here.
*I say “dark moons” but actually Enceladus and Mimas are pretty bright, both being composed of a lot of ice. Enceladus is actually the most reflective world in the Solar System!
