Space Probe Spots A Saturn Moonlet

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Space Probe Spots A Saturn Moonlet

A space probe’s last orbit through Saturn’s rings may finally give scientists a clear image of a small moonlet called Peggy. The spacecraft Cassini has its sights trained on the formation and is aiming for a shot that captures the entirety of the moonlet.

Cassini has been sending a steady stream of images back to Earth for 13 years but is nearing the end of its mission. It is estimated that the craft will succumb to the atmosphere of the ringed planet in September of this year, abruptly stopping the flow of images that have provided scientists with valuable information about Saturn and its rings.

Before the probe is destroyed, professor Carl Murray of Queen Mary University of London hopes to get a close-up of the developing moon. Murray first spotted Peggy on April 15, 2013, and named it after his mother-in-law who shares a birthday with the discovery.

Murray was really looking for Prometheus, a much larger moon associated with Saturn’s F ring, but noticed a small smudge in the background on the A-ring. The smudge turned out to be a tiny, newly formed moonlet that was so small it was only detectable by the disturbance it had caused in the ice and dust surrounding it.

Studying formations like Peggy help researchers to understand how moons and planets form. Saturn’s rings are very similar to the kinds of discs circling far-off new stars and is a miniature example of how planets form around those stars.

“Peggy is evolving. Its orbit is changing with time,” said Murray. “Sometimes it moves out, sometimes it moves in, by just a few kilometers. And this is what we think happens with proto-planets in those astrophysical discs. They interact with other proto-planets and the material in the disc, and they migrate; they move. ”

Though Peggy is small, less than 5 kilometers wide, Cassini’s new orbit should allow it to capture a more clear image and make one last contribution to the scientific community before it is pulled in by the planet it has circled for so long.

Top photo by Kabsik Park CC BY 2.0

Lauren Leising is a freelance writer based in Athens, Georgia.