Birth of 'new Saturn moon' witnessed

Peggy Ring-edge disturbance: The object would become the 63rd moon in Saturn's orbit if confirmed.

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Scientists say they have discovered what could be the birth of a new moon in the rings of Saturn.

Informally named Peggy, the object would become the 63rd moon in Saturn's orbit - if confirmed.

The evidence comes from a black-and-white image of the outermost ring captured by the Cassini spacecraft.

"Witnessing the birth of a tiny moon is an exciting, unexpected event," said Linda Spilker of Nasa's Jet Propulsion Laboratory (JPL).

Scientists noticed a bump or distortion on the edge of the ring that they believe indicates the presence of some kind of object.

It is estimated that Peggy may be about a kilometre (half a mile) in diameter and it is almost certainly made of ice.

Cassini imaging scientist Prof Carl Murray of Queen Mary University of London told BBC News that this was the first time this kind of observation had been made:

"All we know is that something is there - what we can track is the effect of an object in the rings perturbing the particles around it, creating a disturbance in the rings."

The disturbance in the edge of the ring is 20% brighter than its surroundings and about 1,207km (750 miles) long and 9.7km (six miles) wide.

Details were published in the journal Icarus.

The significance of the discovery is that the image may have captured the moment of the moon's birth amid the clouds of ice particles making up the rings.

According to Prof Murray, "the rings are icy, more than 90% pure water-ice, so with the particles colliding you have the ideal conditions for objects to accrete, for objects to form in this region, and images do show this kind of clumpiness".

The most obvious theory is that because the rings contain so much ice, and because many of Saturn's moons are composed primarily of ice, the rings provide the nursery for new moons before they migrate to more distant orbits.

Saturn Saturn's majestic ring system is more than 90% pure water-ice

What happens to Peggy now is not clear. If it continues to orbit inside the rings, it runs the risk of collisions with smaller lumps of ice with the likelihood of the tiny moon disintegrating.

However, if Peggy escapes beyond the rings, it will run the gauntlet of drifting through the paths of much larger moons.

In any event, the moon's small size means that if it does migrate beyond the rings, it will be impossible for the scientists to keep track of it.

Prof Murray said: "Peggy is trying to make its own way in the world. If it escapes, it has to get past some much larger predecessors and if it avoids them it may still get hit by a meteoric bombardment.

"Babies are safer in the womb but they have to leave sometime - and the paradox is that to get to safety Peggy has to pass between other much larger objects."

One hope is that during one of Cassini's final orbits, in 2016, the spacecraft's narrow angle camera may be in a position to offer a far more detailed view of the outermost "A" ring, providing a chance to observe Peggy's fate.

David Shukman Article written by David Shukman David Shukman Science editor

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  • rate this

    Comment number 125.

    This is a pointless discovery that does not contribute to society one bit.

    Still, it will undoubtedly keep scientists on the gravy train, presenting their meaningless papers presented at endless conferences.

    Why don't scientists get proper jobs?

  • rate this

    Comment number 124.

    Astronomy clubs are great, but unlike a fishing club where you can all agree to meet up, and even if the weather is rubbish you can still fish, you can't plan stargazing in advance. The UK is so cloudy that you just have to be prepared to grab your scope and get out when you get the chance - can be damned frustrating!
    (I meant "style" earlier, a stye is bad for observing, even for experts.)

  • rate this

    Comment number 123.

    Yes, this IS news. You people really think completely ficticious economic data is more news than a (possibly) new moon in our solar system?

    Glad there is a few sane heads in this thread.

  • rate this

    Comment number 122.


    Earlier comments recommending you find, and join your local society are good advice. The telescope you were looking at "Celestron PS1000 Newtonian Reflector" seems to have detractors - google for more on that.

    Good luck with your viewing - Saturn, Moonlets and all. Space is truly awe-inspiring and amateurs are still making contributions to our knowledge.

  • rate this

    Comment number 121.


    Thanks for that Chris, I was looking to spend in the region of £150 - £200 for the first one so what you have said fits nicely! I will have a look into what you have said.


Comments 5 of 125



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