Peggy (moonlet)
A former moonlet in Saturn's A Ring, discovered in 2013.
Peggy is the informal name for a moonlet that once existed in the outermost region of Saturn’s A Ring, about 136,775 kilometers from the planet. The Cassini Imaging Team found it in 2013, and it may be in the process of leaving the A Ring. No direct photograph of Peggy has ever been taken. Other moonlets similar to Peggy include Bleriot, Earhart, and Santos-Dumont.
The moonlet was named after the mother-in-law of Carl D. Murray, a professor at Queen Mary University of London, because it was her 80th birthday at the time.
Peggy was first spotted in 2013, though it could have been detected as early as 2012. Two images from Cassini of the A Ring’s edge confirmed it was not a cosmic ray artifact. Disturbances appeared at the ring’s edge, including one patch about 20 percent brighter than its surroundings, and protuberances along the normally smooth boundary.
When first found, no similar object had been seen in Saturn’s main rings. In 2014, Peggy reappeared but was much fainter than in 2013. Carl Murray proposed that it may have collided with something or been gravitationally ejected, but there is no evidence. After 2014, Cassini observations suggested Peggy had broken into two pieces, with the second piece called Peggy B.
Quick Facts
- Discoverer
- Cassini Imaging Team
- Discovered
- 2013
- Semimajor
- 136,775.20 ±0.03km
- Eccentricity
- ≈ 0.000
- Inclination
- ≈ 0.0
- Satellite Of
- Saturn
- Mean Diameter
- 1 km
- Rotation
- assumed synchronous
Facts from the source article.
Lore & Background
The moonlet was first discovered in 2013, although its discovery was possible in 2012. Cassini took two images of the edge of Saturn's A Ring, thereby ruling out it being a cosmic ray artifact. Disturbances were observed at the edges of Saturn's A Ring, with one of these being approximately 20% brighter than its surroundings. There were also protuberances at the edge of the usually smooth A Ring.
When it was first discovered, no similar object had been discovered in Saturn's main rings. The moonlet was then seen again in 2014 but it was much dimmer than it was in 2013. Carl Murray suggests that there may have been a collision or that it was gravitationally ejected, though without evidence. In Cassini observations past 2014, Peggy appears to have broken into two pieces, with the other being named Peggy B.
The name of the moonlet comes from the mother-in-law of Carl D. Murray, a professor at the Queen Mary University of London. Murray named it after his mother-in-law because it was her 80th birthday at the time.
Reader's Guide
Peggy's significance lies in its status as a former moonlet in Saturn's outermost A Ring, discovered by the Cassini Imaging Team in 2013. It is notable because no direct image of it has ever been made, and it may be exiting Saturn's A Ring. The moonlet was first observed through disturbances at the ring edge, including a feature 20% brighter than its surroundings and protuberances. Its discovery was confirmed by two Cassini images that ruled out a cosmic ray artifact. When first found, no similar object had been discovered in Saturn's main rings. By 2014, Peggy appeared much dimmer, and Carl Murray proposed a possible collision or gravitational ejection, though without evidence. Later Cassini observations showed Peggy broken into two pieces, the second named Peggy B. The moonlet's informal name honors Carl D. Murray's mother-in-law on her 80th birthday. Similar moons include Bleriot, Earhart, and Santos-Dumont.
Did You Know?
- Peggy is the informal name for a former moonlet in the outermost part of Saturn's Ring A.
- No direct image of Peggy has ever been made.
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