NASA Cassini Images May Reveal Birth of New Saturn Moon

5

NASA's Cassini spacecraft has documented the formation of a small icy object within the rings of Saturn that may be a new moon, and may also provide clues to the formation of the planet's known moons.

Images taken with Cassini's narrow angle camera on April 15, 2013 show disturbances at the very edge of Saturn's A ring — the outermost of the planet's large, bright rings. One of these disturbances is an arc about 20 percent brighter than its surroundings, 750 miles (1,200 kilometers) long and 6 miles (10 kilometers) wide. Scientists also found unusual protuberances in the usually smooth profile at the ring's edge. Scientists believe the arc and protuberances are caused by the gravitational effects of a nearby object. Details of the observations were published online today (April 14, 2014) by the journal Icarus.

The object is not expected to grow any larger, and may even be falling apart. But the process of its formation and outward movement aids in our understanding of how Saturn's icy moons, including the cloud-wrapped Titan and ocean-holding Enceladus, may have formed in more massive rings long ago. It also provides insight into how Earth and other planets in our solar system may have formed and migrated away from our star, the sun.

"We have not seen anything like this before," said Carl Murray of Queen Mary University of London, and the report's lead author. "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."

The object, informally named Peggy, is too small to see in images so far. Scientists estimate it is probably no more than about a half mile in diameter. Saturn's icy moons range in size depending on their proximity to the planet — the farther from the planet, the larger. And many of Saturn's moons are comprised primarily of ice, as are the particles that form Saturn's rings. Based on these facts, and other indicators, researchers recently proposed that the icy moons formed from ring particles and then moved outward, away from the planet, merging with other moons on the way.

Written By: NASA
continue to source article at nasa.gov

5 COMMENTS

  1. Saturn’s ring system is constantly changing and evolving, with icy particles added by cryo-volcanism, and shepherd-moons shaping and sweeping gaps in the rings. http://www.nasa.gov/multimedia/imagegallery/image-feature-650.html

    Shepherd Moons

    In various instances now we know that ring structures in the Jovian planets are stabilized by small “shepherd moons” that orbit in or near the rings and stabilize them by their gravitational influences. One such example is the F-ring of Saturn, which is kept narrow by two small shepherd moons, Prometheus and Pandora, as illustrated in the adjacent image (click the button for labels). We shall find similar examples of shepherd moons for rings associated with other planets. Although such shepherd satellites clearly play a significant role in ring structures, we only partially understand the details of these roles.
    http://csep10.phys.utk.edu/astr161/lect/saturn/moons.html

    • In reply to #1 by Alan4discussion:

      Saturn’s ring system is constantly changing . . .

      Yeah, but they like to grab headlines by describing it as ‘ooh we think we see a new moon forming’. I suppose it sounds more interesting than saying ‘”Yep, something similar happened again today!”

      I read this report on the BBC News website this morning and there were several comments asking why it had even been reported as news.

      • In reply to #2 by Lonevoice:

        I read this report on the BBC News website this morning and there were several comments asking why it had even been reported as news.

        “We have not seen anything like this before,” said Carl Murray of Queen Mary University of London, and the report’s lead author. “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.”

        Would it help if they reported that a militant ring particle faction was fighting the rebel ring particles to remain associated with the ring system? A dirty ice political coup? An assassination attempt on the gravitational non-ring leader? A secret affair with one of the ring particles back home?

        I don’t understand what is missing for the good posters on the BBC News site to consider this a news story.

  2. @OP “We have not seen anything like this before,” said Carl Murray of Queen Mary University of London, and the report’s lead author. “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.”

    Perhaps he should have looked a little further!

    Are Asteroids Rubble Piles? http://www.spaceacademy.net.au/watch/neo/rubble.htm

    As ground imaging techniques improve and as more spacecraft make close encounters with asteroids we are increasingly observing that an asteroid may not be a single body. Several asteroids have now been discovered that have two or more components gravitationally bound to each other. Many researchers now consider that even when an asteroid looks to be a single body, it may in fact be composed of many smaller rocks loosely held together by their mutual gravitational force.

    This has led to development of the “rubble pile” model for an asteroid. The main fact that seems to suggest that many asteroids may in fact fit this model is the observation that no asteroid more than 200 metres in diameter has a rotational period less than about 2.3 hours. In fact there seems to be a sharp cutoff at around this value. A rubble pile could not have a rotation faster than this value without flying to pieces.

    Orbiting materials accreting into orbiting bodies. Stars, planets, moons, asteroids, comets, solar-systems! Mmmm Where have I seen this before??

    • In reply to #4 by Alan4discussion:

      @OP “We have not seen anything like this before,” said Carl Murray of Queen Mary University of London, and the report’s lead author. “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.”

      Perhaps he should have looked a li…

      I don’t know what was in Carl Murray’s mind when he said that but I assume he means we have no images of formation by accretion as it is happening (which is what these images may show). I doubt he meant that statement even that broadly as I also assume he is referring to ring dynamics in particular (as the second half of his statement suggests). The point is having theories of formation and a set of images where we watch it happen are two different things.

Leave a Reply