Discovery [1] | |
---|---|
Discovered by | Brett J. Gladman |
Discovery site | Observatoire de la Cote d'Azur |
Discovery date | 2000 |
Designations | |
Designation | Saturn XIX |
Pronunciation | /ˈiːmɪər/, [2] /ˈɪmɪər/ [3] |
Named after | Ymir |
S/2000 S 1 | |
Adjectives | Ymirian /ɪˈmɪəriən/ [a] [5] |
Orbital characteristics [6] | |
Epoch 2000 January 1.5 | |
22957100 km | |
Eccentricity | 0.337 |
−3.6 yr (−1315.16 d) | |
344.3° | |
Inclination | 173.1° |
61.5° | |
90.8° | |
Satellite of | Saturn |
Group | Norse group |
Physical characteristics [7] [8] [9] | |
Dimensions | 24 km × 22 km × 16 km |
Mean diameter | 19+50% −30% km |
Circumference | 65 km (equatorial) |
−11.92220±0.00002 h | |
North pole
right ascension | 280°±20° [b] |
North pole
declination | 70°±10° [b] |
Albedo | 0.06 [10] |
Spectral type | D/ P |
21.7 [11] | |
12.3 | |
Ymir /ˈiːmɪər/, or Saturn XIX, is the second-largest retrograde irregular moon of Saturn. It was discovered by Brett J. Gladman, et al. in 2000, and given the temporary designation S/2000 S 1. It was named in August 2003 after Ymir, who in Norse mythology is the ancestor of all the Jotuns or frost giants. [12]
It takes 3.6 Earth years to complete an orbit around Saturn. Of the moons that take more than 3 Earth years to orbit Saturn, Ymir is the largest, at about 19 kilometres (12 miles) in diameter; [11] Ymir is also the second largest member of the Norse group, after Phoebe. [9]
Spectral measurements from Cassini–Huygens show that Ymir is reddish in color, unlike Phoebe's gray color, suggesting a separate origin for this moon. It shows a similar light curve as Siarnaq and has a triangular shape, rotating in a retrograde direction about once every 11.9 hours. [9]
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