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 6.

    Amazing stuff. I'm guessing in about 30 minutes this thread will be filled with people stating how pointless this exercise was or how astronomy has no use, i'll pre-empt them with a list of discoveries that came from the space age:
    1) Memory Foam
    2)Shoe Insoles
    3) Long distance telephone calls
    4) Smoke detectors
    5) Cordless tools
    6) Water filters
    7) Protective paint
    8) Scratch resistant lenses

  • rate this

    Comment number 12.

    Baron_of_Bristol - I saw the rings of Saturn 30 years ago with my own eyes, through a telescope. It was one of most incredible things I had ever seen - completely different from just seeing it on TV or in a book. It turned me on to Astronomy and I ended up doing an Astrophysics degree at University.
    You only need a relatively inexpensive telescope to see the rings - I suggest you have a go!

  • rate this

    Comment number 49.

    We need stories like this. Contrary to what many people think lots of ordinary people are interested in the ins and outs of scientific discovery even if they don't hold advanced degrees. You don't get people interested in science by denying it them. "So what" Some people might say. I say it matters a lot, if only to engage peoples curiosity. Personally I find it fascinating.

  • rate this

    Comment number 46.

    Amazing discovery that will surely amaze and interest children but what a pity so many adults feel the need to ridicule the story.

  • rate this

    Comment number 9.

    6. Shed

    I'll add that Wifi and mobile phones standards and technologies came out of radio astronomy (which had to deal with radio waves being reflected off tall buildings, hills etc). Of course the modern scientific method emerged out of astronomy with Kepler, Galileo, Newton onwards.


Comments 5 of 125



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