Mundilfari (moon)
Bluest moon studied, second-fastest rotator among Saturn's irregulars.
Mundilfari, also designated Saturn XXV, is a natural satellite of Saturn discovered in 2000 by Brett J. Gladman et al. It is a small, irregular moon about 7 kilometers in diameter, notable for being the bluest of all moons studied by Grav and Bauer (2007), slightly more so than Phoebe and about as blue as Erriapus is red, and for having the second-fastest rotation period among irregular moons studied by Cassini–Huygens, after Hati. It is the largest remaining fragment of an eponymous sub-group of small retrograde irregular moons belonging to the Norse group.
Quick Facts
- Mpc Name
- Saturn XXV
- Pronounced
- is · ˈmʏntɪlvarɪ · lang
- Named After
- Mundilfari
- Discoverer
- Gladman et al.
- Discovered
- 2000
- Inclination
- 168.4°
- Eccentricity
- 0.210
- Period
- −952.95 days
- Satellite Of
- Saturn
- Group
- Norse group
- Dimensions
- 11.78 × 7 × 5.86 kmModeled using the diameter calculated from the assumed albedo.
Facts from the source article.
Lore & Background
Mundilfari was discovered in 2000 by Brett J. Gladman et al. and given the temporary designation S/2000 S 9. It was named in August 2003 from Norse mythology, where Mundilfari is the father of the goddess Sól (Sun) and the god Máni (Moon). The moon orbits Saturn at an average distance of 18,5903 Mm in 952.95 days, with an eccentricity of 0.210 and an inclination of 168.4° to the ecliptic in a retrograde sense. Its rotation period is 6.74±0.08 hours, the second-fastest among all the irregular moons studied by Cassini–Huygens after Hati, and it appears to be very elongated in shape. With a spectral slope of −5.0%/100, Mundilfari is the bluest of all the moons studied by Grav and Bauer (2007), slightly more so than Phoebe (−2.5%/100 nm) and about as blue as Erriapus (+5.1%/100 nm) is red.
Reader's Guide
Mundilfari may have formed from debris knocked off Phoebe by large impacts at some point in the Solar System's history, but the article notes that its orbit is sufficiently different from Phoebe that this may be difficult to reconcile. This uncertainty is preserved, highlighting the ongoing challenge in understanding the origins of Saturn's irregular moons. As the largest remaining fragment of an eponymous sub-group of small retrograde irregular moons belonging to the Norse group, Mundilfari serves as a key representative of its dynamical family. Its extremely blue spectral slope, the bluest among moons studied by Grav and Bauer (2007), distinguishes it from other irregular satellites and suggests a unique surface composition or history. The moon's rapid rotation and elongated shape, observed by Cassini–Huygens, further add to its distinctiveness among Saturn's irregular moons. Its naming from Norse mythology connects it to the cultural tradition of naming Saturn's moons after figures from that mythology.
Did You Know?
- Its rotation period of 6.74±0.08 hours is the second-fastest among irregular moons studied by Cassini–Huygens, after Hati.
- It was named in August 2003 from Norse mythology as the father of the goddess Sól and the god Máni.
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