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Pallene (pronounced pal-lee-nee, adjective: Pallenean) is a tiny 4-kilometer (3-mile) diameter moon that orbits between Mimas and Enceladus at about 211,000 kilometers (131,000 miles) from Saturn. Scientists have two theories to explain the presence of Pallene and two other tiny sister moons, Methone and Anthe. First, the three moons may have split from either Mimas or Enceladus. Second, all five moons may be the remains of a larger swarm that traveled in that area close to Saturn. Pallene circles Saturn in approximately 27.7 hours
Because these three tiny moons orbit at very similar distances from Saturn, they are in a dynamical relationship. Mimas strongly perturbs Pallene, the 3-kilometer (2-mile) diameter moon Methone, and the 2-kilometer (1-mile) diameter moon Anthe, all of which orbit between Mimas and the next major moon, Enceladus. The vastly more massive Mimas causes the orbits of the tiny moons to vary by as much as 20 kilometers (12.4 miles).
These three moons may also be contributing particles to Saturn's E-ring. The moons are small and were only recently discovered. Consequently, astronomers have few details on characteristics of these moons such as reflectivity (albedo), rotation (probably tidally locked on Saturn because they are so close), and composition.
Discovery
The Cassini Imaging team discovered Pallene on June 1, 2004. Pallene and nearby Methone were the first moons discovered in Cassini images.
Origin of Name
John Herschel suggested that the moons of Saturn be associated with Greek mythical brothers and sisters of Kronus, known to the Romans as Saturn. The International Astronomical Union now controls the official naming of astronomical bodies.
The name Pallene comes from the name in Greek mythology of one of seven Alkyonides, daughters of the god (or Titan) Alkyoneus who was born of Gaia and the blood of Uranus. Herakles (Hercules) killed their father in the war between the gods of Mount Olympus and the titans. Overcome by grief, the seven daughters threw themselves into the sea to die, but the goddess Amphitrite took pity on them and transformed them into halcyons or kingfishers.
Astronomers also refer to Pallene as Saturn XXXIII and as S/2004 S2. Pallene has been determined to be the same object spotted in a single image taken by NASA's Voyager spacecraft in the 1980s, at that time known as S/1981 S14.
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Flyby Dates |
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- No targeted flyby.
Closest approach: May 25, 2008 -- 19,536 kilometers (12,139 miles)
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Fast Facts |
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- Discovered in June 2004 by the Cassini imaging team
- Distance from Saturn: 211,000 km (about 131,100 miles)
- Period of Orbit around Saturn: 26 hours
- Diameter: 4 km (2.5 miles)
- Mass: unknown
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Science Goals |
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- Determine the characteristics and geological history of Pallene
- Define the different physical processes that created the surface of Pallene
- Investigate composition and distribution of surface materials on Pallene -- particularly dark, organic-rich material and condensed ice
- Determine the bulk composition and internal structure of Pallene
- Investigate interaction of Pallene with Saturn's magnetosphere and ring system
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Saturn's Moons (sorted alphabetically) |
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