Prometheus a shepherd moon of Saturn. Image Credit: NASA/JPL-Caltech/Space Science Institute
The little moon Prometheus is featured in this image is creating channels (gores) and streamers in the F ring of Saturn. Prometheus and Pandora are believed to be responsible for much of the structure of the ring. Can’t see the moon? Look at the speck at about 10 O’clock.
Prometheus is only 86 km (53 miles) across and has an orbit that regularly brings it to the F ring. When the encounter occurs as we can see the gores where it enters and streamers pulled away in its wake as it exits.
There is a movie of this happening and you can see it here.
Cassini see a blue orb on the horizon. Click for larger. NASA/JPL-Caltech/Space Science Institute
It’s not us though, Cassini gets an image of Saturn’s neighbor Uranus for the first time. It’s the bright blue dot in the top-left. Although it has been brightened in this image, it is pretty much that color. I’ve taken images and they were never this good of course but color did show, I’ll see if I can find them.
The little moon Pan is minding the (Enke) gap. Image: NASA/JPL-Caltech/Space Science Institute
If you’ve ever wondered how the Enke gap in the rings of Saturn can be, it is thanks to the tiny moon Pan who minds the gap, keeping it nice and orderly using its gravity. Pan is so small it barely shows up in the image above.
BTW: If you are out and about just after sunset and in the twilight AND have decent skies, look to the south, on your left or East about 15 degrees you will see the planet Mars, nice and red then on the right or West about 15 degrees you will see the bright blue star Sirius. I saw the two last evening and quite enjoyed it, the colors were really good against the twilight sky.
Here’s the Cassini caption from JPL:
Saturn’s moon Pan, named for the Greek god of shepherds, rules over quite a different domain: the Encke gap in Saturn’s rings.
Pan (17 miles, or 28 kilometers across) keeps the Encke gap open through its gravitational influence on the ring particles nearby.
The final journey of Cassini. Image: NASA
As hard as it seems, the Cassini spacecraft soon enough enter the final phase of its mission.
The new and final mission will begin in 2016 and promises to be incredible.
During this final phase the spacecrafts orbit will take it well above the north pole of Saturn, it will then plunge between the inner ring and the planet itself.
You can get the details of the final months of Cassini here.
In the mean time the Cassini team is looking for a name to call the mission and YOU can help.
Pick a name from a list.
Submit a name of your own.
A small icy object named Peggy in the rings of Saturn. Image: NASA/JPL-Caltech/Space Science Institute
An “object”, dubbed Peggy located at the edge of the rings seen here at the bottom is being described as a “Small Icy Object”; might it be a new moon forming? Maybe, although it’s not expected to grow any larger, Peggy gives a good look at how a moon could form. It’s all new to everybody because this has never been seen before – a common theme with the Cassini mission. An epic mission for sure.
Here’s the story at NASA.
A possible internal structure of Enceladus. Artist concept: NASA/JPL-Caltech
I love this! I know, it’s not “for sure positively” but close enough for me. I was in the “global ocean” camp, then I thought “why not” this seems perfectly reasonable.
I do have to take issue with the very last line of the ESA press release (included / linked below): “This experiment provides a crucial new piece of information towards understanding the formation of plumes on this intriguing moon,” says Nicolas Altobelli, ESA’s Cassini project scientist. Yeah it does provide a piece, but seems like it brings up more questions than it answered. That’s awesome is what it is!
Here is the Enceladus image gallery from NASA.
The press release from ESA is excellent:
Saturn’s icy moon Enceladus has an underground sea of liquid water, according to the international Cassini spacecraft.
Understanding the interior structure of 500 km-diameter Enceladus has been a top priority of the Cassini mission since plumes of ice and water vapour were discovered jetting from ‘tiger stripe’ fractures at the moon’s south pole in 2005.
Subsequent observations of the jets showed them to be relatively warm compared with other regions of the moon and to be salty – strong arguments for there being liquid water below the surface.
The churning atmosphere of Saturn. Copyright NASA/JPL-Caltech/SSI/Hampton University
I was having a look at the ESA Space in Images page and they had this image of the stormy atmosphere of Saturn. We tend to be more used to seeing this sort of activity in the atmospheric bands of Jupiter, Saturn shares similar storm processes (and banding) although the colors tend to be more muted. The image colors were enhanced to tease out the visual details as explained below in the ESA caption.
Like a swirl from a paintbrush being dipped in water, this image from the Cassini orbiter shows the progress of a massive storm on Saturn. The storm first developed in December 2010, and this mosaic captures how it appeared on 6 March 2011.
The head of the storm is towards the left of the image, where the most turbulent activity is shown in white, but towards the centre you can also see the trace of a spinning vortex in the wake of the storm.
This image, centred at about 0º longitude and 35º N latitude, has had its colours enhanced to help reveal the complex processes in Saturn’s weather. The white corresponds to the highest cloud tops, but to the human eye the storm would appear more as a bright area against a yellow background.
Four moons of Saturn at once! Click for larger. Credit: NASA/JPL-Caltech/Space Science Institute
We get to see four of Saturn;s moons in this Cassini image. NASA describes them below. They do not comment on one of more spectacular shots of the rings Cassini has taken; they show up better in the larger versions at the NASA website.
Two pairs of moons make a rare joint appearance. The F ring’s shepherd moons, Prometheus and Pandora, appear just inside and outside of the F ring (the thin faint ring furthest from Saturn). Meanwhile, farther from Saturn the co-orbital moons Janus (near the bottom) and Epimetheus (about a third of the way down from the top) also are captured.
Prometheus (53 miles, or 86 kilometers across) and Pandora (50 miles, or 81 kilometers across) sculpt the F ring through their gravitational influences. Janus (111 miles, or 179 kilometers across) and Epimetheus (70 miles, or 113 kilometers across) are famous for their orbital dance, swapping places about every four years. They are also responsible for gravitationally shaping the outer edge of the A ring into seven scallops.
This view looks toward the sunlit side of the rings from about 47 degrees above the ringplane. The image was taken in visible light with the Cassini spacecraft wide-angle camera on Oct. 11, 2013.
The view was acquired at a distance of approximately 810,000 miles (1.3 million kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 47 degrees. Image scale is 47 miles (76 kilometers) per pixel.
Continuing on this weekend’s theme:
13 years of Cassini for a Day! This is a great opportunity for both teachers and students, espeically students. Looking for a project? You could enter this and (or) use the essay at school. Surely an entry would earn some extra credit.
Students must be in grades 5 to 12 and the entry deadline is 17 April 2014. Note: that is a US deadline, other counties may have different deadlines which are not yet listed, typically they indeed different. The International link on the site is not yet current but it will be shortly.
Check out the Cassini Scientist for a Day website.
The contest meets U.S. National English and Science Education Standards.
Cassini Scientist for a Day is an essay contest designed to give students a taste of life as a scientist.
Students study three possible targets that the Cassini spacecraft can image during a given time set aside for education. They are to choose the one image they think will yield the best science results and explain their reasons in an essay.
The three targets are:
- Target 1 is Saturn’s F ring. Cassini will be taking 70 images of the F ring using the spacecraft’s Narrow Angle Camera to make a movie showing how the F ring changes as it orbits Saturn.
- Target 2 is Saturn’s largest moon, Titan. Cassini will be taking nine images of Titan’s north polar region using its Narrow Angle Camera. These images will be stitched together to form a mosaic.
- Target 3 is the planet Saturn. The Cassini spacecraft will use its Wide Angle Camera and its Narrow Angle Camera to image Saturn’s north pole, studying the hurricane at the north pole and the hexagon-shaped polar vortex.
The Saturn moon Rhea. Image Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
It has been quite a while since I’ve seen the Saturn moon Rhea so I thought I’d put this recent Cassini offering up.
A nearly full Rhea shines in the sunlight in this recent Cassini image.
Rhea (949 miles, or 1,527 kilometers across) is Saturn’s second largest moon.
Lit terrain seen here is on the Saturn-facing hemisphere of Rhea. North on Rhea is up and rotated 43 degrees to the left. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Sept. 10, 2013.
The view was obtained at a distance of approximately 990,000 miles (1.6 million kilometers) from Rhea. Image scale is 6 miles (9 kilometers) per pixel.
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 in Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging team is based at the Space Science Institute, Boulder, Colo.