Enceladus and Epimetheus as seen by Cassini on October 1, 2011.
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Taken during the Cassini spacecraft’s October 1 flyby of Saturn’s ice-spewing moon, this image – released today – shows a crescent-lit Enceladus with southern geysers in action… and the much smaller Epimetheus peeking out from behind!
Epimetheus
The 70-mile (113-km) -wide Epimetheus is dwarfed by its larger sibling Enceladus, which is 313 miles (504 km) in diameter… about the width of the state of Arizona.
One of the most reflective objects in the solar system, Enceladus appears to be casting some reflected light onto Epimetheus as well. (Image processors at the Cassini Imaging Lab have brightened the moons by a factor of 1.8 relative to the rings in order to bring out detail.)
Some bright clumps of material can also be seen orbiting within Saturn’s rings at upper left, possibly stirred up by the movement of the shepherd moon Pan.
And I agree with Cassini imaging team lead Carolyn Porco who said on Twitter of this image: “You’d have to be dead to tire of such magnificent vistas of alien worlds. Eerie Titan, the rings, Pan & Pandora. Glory!”
Titan is the largest in the background, and also the largest moon at 5,150 kilometres (3,200 miles) across, with Dione in front of it, which is 1,123 kilometres (698 miles) in diameter. Just to the right of the edge of the rings is Pandora, which is only about 81 kilometres (50 miles) in diameter. Tiny little Pan, only about 28 kilometres (17 miles) across, can just barely be seen as a speck inside the Encke Gap of the A ring on the left side of the image (look closely!).
Another amazing natural montage showing the alien beauty of the worlds in the Saturnian system. The full-size image can be seen here.
Enceladus and Tethys hang below Saturn's rings in this image from the Cassini spacecraft. Credit: NASA/JPL-Caltech/SS
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Another Cassini stunner! This gorgeous, suitable-for-framing image shows two of Saturn’s moons hanging below the planet’s rings, as if strung on a necklace. Beautiful! Enceladus (504 kilometers, 313 miles across) appears just below the rings, while Tethys (1062 kilometers, 660 miles across) appears below. In this shot, Cassini is also closer to Tethys than Enceladus: the spacecraft is 208,000 kilometers (139,000 miles) from Tethys and 272,000 kilometers (169,000 miles) from Enceladus. This image was taken on September 13, 2011.
See below for some raw images from Cassini’s October 1 close fly by of Enceladus, including a great shot of the moon hovering in front of Saturn’s rings, and a view of the geysers.
A closeup view of Enceladus with Saturn's rings in the background. This raw image was taken on Oct. 1, 2011. Credit: NASA/JPL/Space Science Institute
A view of Enceladus from farther away, with the rings slicing through the view of Saturn in the background. Credit: NASA/JPL/Space Science InstituteA view of the geysers on Enceladus, from Cassini's latest close flyby of the moon, on October 1, 2011.Credit: NASA/JPL/Space Science Institute
If you’re reading this, you’re probably very well aware of the Cassini mission. Launched in 1997, the Cassini spacecraft arrived at Saturn in June of 2004 and has been faithfully returning image after beautiful image of Saturn, its rings and its very extended family of moons ever since – not to mention all the groundbreaking scientific discoveries it’s made about the Saturnian system… and our solar system as a whole. Cassini truly is a rock star in the world of robotic space exploration, and now it has its own Hall of Fame to show off some of its best work!
The Cassini mission site put up by JPL/Caltech regularly features news and images from the mission, even including the latest downlinked raw image data from the spacecraft. In this way anyone can keep up with what Cassini is seeing and when, far before the images are included in NASA’s Planetary Data System. The new Cassini Image Hall of Fame showcases the “best of the best” from the mission, and is a great way to revisit Cassini’s past discoveries. (With so much happening at Saturn, sometimes it’s easy to forget all the amazing things Cassini has brought to our attention!)
Revisit the best of the best images of Saturn
If you’re a fan of Saturn (and really, who isn’t?) be sure to check this out. With the current mission extended into 2017 there’s sure to be lots more additions to the Hall of Fame on the way, too!
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA’s Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colorado.
Also, be sure to visit the hard-working Cassini imaging team’s homepage at http://ciclops.org… they are the ones responsible for all these fantastic images in the first place!
A quintet of Saturn's moons come together in the Cassini spacecraft's field of view for this portrait. From left to right: Janus, Pandora, Enceladus, Mimas and Rhea. Credit: NASA/JPL-Caltech/Space Science Institute
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Check out this gorgeous new portrait of a Saturnian moon quintet taken by Earths’ emissary – NASA’s Cassini Orbiter. The moons are majestically poised along a backdrop of Saturn’s rings, fit for an artist’s canvas.
Janus, Pandora, Enceladus, Mimas and Rhea are nearly lined up (from left to right) in this view acquired by Cassini at a distance of approximately 684,000 miles (1.1 million kilometers) from Rhea and 1.1 million miles (1.8 million kilometers) from Enceladus.
The newly released image was taken by Cassini’s narrow angle camera on July 29, 2011. Image scale is about 4 miles (7 kilometers) per pixel on Rhea and 7 miles (11 kilometers) per pixel on Enceladus.
Cassini will stage a close flyby of Enceledus – Satarn’s geyser spewing moon – in about two weeks, swooping within 99 km
Moon Facts from JPL:
Janus (179 kilometers, or 111 miles across) is on the far left. Pandora (81 kilometers, or 50 miles across) orbits between the A ring and the thin F ring near the middle of the image. Brightly reflective Enceladus (504 kilometers, or 313 miles across) appears above the center of the image. Saturn’s second largest moon, Rhea (1,528 kilometers, or 949 miles across), is bisected by the right edge of the image. The smaller moon Mimas (396 kilometers, or 246 miles across) can be seen beyond Rhea also on the right side of the image.
This view looks toward the northern, sunlit side of the rings from just above the ring plane. Rhea is closest to Cassini here. The rings are beyond Rhea and Mimas. Enceladus is beyond the rings.
The simple graphic below shows dozens of Saturn’s moons – not to scale. So far 62 have been discovered and 53 have been officially named.
Saturn’s moons. Click on link below to learn more about each moon. Credit: NASA/JPL
Learn more about Saturn’s moons at this link
This raw, unprocessed image of Hyperion was taken on August 25, 2011 and received on Earth August 26, 2011. Image credit: NASA/JPL-Caltech/Space Science Institute
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It might be one of the weirdest-looking moons in the solar system: Saturn’s moon Hyperion looks like a giant sponge. Additionally, its eccentric orbit makes it subject to gravitational forces from Saturn, so it is just tumbling along, almost out of control. Just yesterday, August 25, 2011, the Cassini spacecraft made a relatively close flyby of Hyperion (24,000 km 15,000 miles away) and took some amazing images.
“Hyperion is a small moon … just 168 miles across (270 kilometers)… orbiting between Titan and Iapetus,” said Carolyn Porco in an email. Porco is the Cassini imaging team lead. “It has an irregular shape and surface appearance, and it rotates chaotically as it tumbles along in orbit, making it impossible to say just exactly what terrain we would image during this flyby.”
See some more of the shots below:
Side view taken by NASA's Cassini spacecraft of Saturn's moon Hyperion. Image credit: NASA/JPL-Caltech/Space Science Institute
Scientists say this flyby’s closeness has likely allowed Cassini’s cameras to map new territory. At the very least, it will help scientists improve color measurements of the moon. It will also help them determine how the moon’s brightness changes as lighting and viewing conditions change, which can provide insight into the texture of the surface. The color measurements provide additional information about different materials on the moon’s deeply pitted surface.
A darker view of Hyperion. Credit: NASA/JPL-Caltech/Space Science InstituteNASA's Cassini spacecraft obtained this unprocessed image of Saturn's moon Hyperion on Aug. 25, 2011. Image credit: NASA/JPL-Caltech/Space Science Institute
The next closest pass of Hyperion is coming up again soon: Sept. 16, 2011, when it passes the tumbling moon at a distance of about 36,000 miles (58,000 kilometers).
Shortly after forming, Jupiter was slowly pulled toward the sun. Saturn was also pulled in and eventually, their fates became linked. When Jupiter was about where Mars is now, the pair turned and moved away from the sun. Scientists have referred to this as the "Grand Tack," a reference to the sailing maneuver. Credit: NASA/GSFC
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Jupiter hasn’t always been in the same place in our solar system. Early in the history of our solar system, Jupiter moved inward towards the sun, almost to where Mars currently orbits now, and then back out to its current position.
The migration through our solar system of Jupiter had some major effects on our solar system. Some of the effects of Jupiter’s wanderings include effects on the asteroid belt and the stunted growth of Mars.
What other effects did Jupiter’s migration have on the early solar system and how did scientists make this discovery?
In a research paper published in the July 14th issue of Nature, First author Kevin Walsh and his team created a model of the early solar system which helps explain Jupiter’s migration. The team’s model shows that Jupiter formed at a distance of around 3.5 A.U (Jupiter is currently just over 5 A.U from the sun) and was pulled inward by currents in the gas clouds that still surrounded the sun at the time. Over time, Jupiter moved inward slowly, nearly reaching the same distance from the sun as the current orbit of Mars, which hadn’t formed yet.
“We theorize that Jupiter stopped migrating toward the sun because of Saturn,” said Avi Mandell, one of the paper’s co-authors. The team’s data showed that Jupiter and Saturn both migrated inward and then outward. In the case of Jupiter, the gas giant settled into its current orbit at just over 5 a.u. Saturn ended its initial outward movement at around 7 A.U, but later moved even further to its current position around 9.5 A.U.
Astronomers have had long-standing questions regarding the mixed composition of the asteroid belt, which includes rocky and icy bodies. One other puzzle of our solar system’s evolution is what caused Mars to not develop to a size comparable to Earth or Venus.
Artist's conception of early planetary formation from gas and dust around a young star. Image Credit: NASA/JPL-Caltech
Regarding the asteroid belt, Mandell explained, “Jupiter’s migration process was slow, so when it neared the asteroid belt, it was not a violent collision but more of a do-si-do, with Jupiter deflecting the objects and essentially switching places with the asteroid belt.”
Jupiter’s slow movement caused more of a gentle “nudging” of the asteroid belt when it passed through on its inward movement. When Jupiter moved back outward, the planet moved past the location it originally formed. One side-effect of caused by Jupiter moving further out from its original formation area is that it entered the region of our early solar system where icy objects were. Jupiter pushed many of the icy objects inward towards the sun, causing them to end up in the asteroid belt.
“With the Grand Tack model, we actually set out to explain the formation of a small Mars, and in doing so, we had to account for the asteroid belt,” said Walsh. “To our surprise, the model’s explanation of the asteroid belt became one of the nicest results and helps us understand that region better than we did before.”
With regards to Mars, in theory Mars should have had a larger supply gas and dust, having formed further from the sun than Earth. If the model Walsh and his team developed is correct, Jupiter foray into the inner solar system would have scattered the material around 1.5 A.U.
Mandell added, “Why Mars is so small has been the unsolvable problem in the formation of our solar system. It was the team’s initial motivation for developing a new model of the formation of the solar system.”
An interesting scenario unfolds with Jupiter scattering material between 1 and 1.5 AU. Instead of the higher concentration of planet-building materials being further out, the high concentration led to Earth and Venus forming in a material-rich region.
The model Walsh and his team developed brings new insight into the relationship between the inner planets, our asteroid belt and Jupiter. The knowledge learned not only will allow scientists to better understand our solar system, but helps explain the formation of planets in other star systems. Walsh also mentioned, “Knowing that our own planets moved around a lot in the past makes our solar system much more like our neighbors than we previously thought. We’re not an outlier anymore.”
This image from the Cassini spacecraft, shows a huge arrow-shaped storm measuring 1,500km in length. Image Credit: NASA/JPL/SSI
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Titan is making news again, this time with Cassini images from 2010 showing a storm nearly as big as Texas. Jonathan Mitchell from UCLA and his research team have published their findings which help answer the question:
What could cause such large storms to develop on a freezing cold world?
For starters, the huge arrow isn’t a cosmic detour sign reminding us to “Attempt No Landings” on Jupiter’s moon Europa.
In the study by Mitchell and his team, a model of Titan’s global weather was created to understand how atmospheric waves affect weather patterns on Titan. During their research, the team discovered a “stenciling” effect that creates distinct cloud shapes, such as the arrow-shaped cloud shown in the Cassini image above.
“These atmospheric waves are somewhat like the natural, resonant vibration of a wine glass,” Mitchell said. “Individual clouds might ‘ring the bell,’ so to speak, and once the ringing starts, the clouds have to respond to that vibration.”
Titan is the only other body in the solar system (aside from Earth) known to have an active “liquid cycle”. Much like Titan’s warmer cousin Earth, the small moon has an atmosphere primarily composed of Nitrogen. Interestingly enough Titan’s atmosphere is roughly the same mass as Earth’s and has about 1.5 times the surface pressure. At the extremely low temperatures on Titan, hydrocarbons such as methane appear in liquid form, rather than the gaseous form found on Earth.
With an active liquid both on the surface and in the atmosphere of Titan, clouds form and create rain. In the case of Titan, the rain on the plain is mainly methane. Water on Titan is rock-hard, due to temperatures hovering around -200 c.
Studies of Titan show evidence of liquid runoff, rivers and lakes, further emphasizing Titan’s parallels to Earth. Researchers believe better understanding of Titan may offer clues to understanding Earth’s early atmosphere. In another parallel to earth, the weather patterns on Titan created by the atmospheric waves can create intense rainstorms, sometimes with more than 20 times Titan’s average seasonal rainfall. These intense storms may cause erosion patterns that help form the rivers seen on Titan’s surface. Mitchell described Titan’s climate as “all-tropics”, basically comparing the weather to what is usually found near Earth’s equator. Could these storms be Titan’s equivalent of monsoon season?
Mitchell stated “Titan is like Earth’s strange sibling — the only other rocky body in the solar system that currently experiences rain”. Mitchell also added, “In future work, we plan to extend our analysis to other Titan observations and make predictions of what clouds might be observed during the upcoming season”.
The research was published Aug. 14 in the online edition of the journal Nature Geoscience .
Image of Tethys and Titan taken in green visible light on July 14th 2011. Image Credit: NASA/JPL-Caltech/Space Science Institute
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In this new image from the Cassini Imaging Team Saturn’s moon Titan looks a little out of focus compared to the sharp, cratered surface of Tethys, seen in the foreground. But that’s only because Titan’s hazy atmosphere makes the moon look blurry. Titan’s current atmosphere is thought to resemble Earth’s early atmosphere, so we could be looking at an analog of early Earth.
And so, the Cassini mission is sharpening our understanding of Saturn and all its moons, but it might help us understand our own planet, as well.
At just over 1,000 kilometers in diameter, Tethys is believed to be almost entirely comprised of water ice, based on density estimates. Titan, at just over 5,000 kilometers in diameter is notable for being the second largest moon in our solar system, as well as having an atmosphere 1 1/2 times thicker than Earth. Titan is also known to have an active “liquid cycle” made up of various hydrocarbons, making Titan the second body in the solar system to have stable liquid on its surface.
The camera view is aimed at the Saturn-facing side of Titan and at the area between the trailing hemisphere and anti-Saturn side of Tethys. Not shown in frame is Saturn, which would be far to the left, from the perspective shown in the image.
The image was acquired with Cassini’s narrow-angle camera, in green visible light, on July 14, 2011. At a distance of roughly 3 million kilometers, the image scale for Titan is 19 kilometers per pixel. With Tethys at a distance of about 2 million kilometers, the image scale is roughly 11 kilometers per pixel.
This Cassini raw image shows a portion of Saturn's rings along with several moons. How many can you find? Credit: NASA/JPL/Space Science Institute
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This stunning new Cassini image was captured on July 29, 2011, and shows a portion of Saturn’s rings along with several moons dotting the view. How many moons can you find, and can you name them?
See below for a color version of this image, put together by our own Jason Major!
Saturns moons and rings, in color. Credit: NASA / JPL / SSI. Edited by Jason Major. Click for larger version.
Jason shares on his Flickr page the process of how he edited the image. As Jason says, it’s a moon flash mob!
