Ymir (moon)

Ymir
Provisional or systematic name	S / 2000 S 1
Central body	Saturn
Properties of the orbit
Major semi-axis	23,130,000 km
Periapsis	15,320,000 km
Apoapsis	30,760,000 km
eccentricity	0.334
Orbit inclination	173.50 °
Orbital time	1315.6 d
Mean orbital velocity	1.27 km / s
Physical Properties
Albedo	0.06
Apparent brightness	21.7 mag
Medium diameter	≈ 18 km
Dimensions	≈ 4.9 × 10 15 kg
Medium density	2.3 g / cm 3
Sidereal rotation	11.92220 h
Acceleration of gravity on the surface	≈ 0.004 m / s 2
Escape speed	≈ 8.5 m / s
discovery
Explorer	Brett Gladman et al.
Date of discovery	August 7, 2000

Ymir (also Saturn XIX) is the third outer known moon of the planet Saturn .

discovery

The discovery of Ymir by Brett Gladman on recordings from August 7th to September 29th, 2000, was announced on October 25th, 2000. Ymir was initially given the provisional designation S / 2000 S 1.

The moon was named after Ymir , the ancient giant of Nordic mythology .

Orbit data

Ymir orbits Saturn on an eccentric orbit at a mean distance of 23,130,000 km in 1,315.6 days or 3.6 years. The orbital eccentricity is 0.33. The orbit is inclined 173.5 ° to the ecliptic and is therefore retrograde, i.e. That is, the moon runs around the planet in the opposite direction to the direction of rotation of Saturn.

Structure and physical data

Ymir has a diameter of 18 km. It has a very dark surface with an albedo of about 0.06, i.e. H. only 6% of the incident sunlight is reflected .

With an apparent brightness of 21.7 ^m , Ymir is an extremely faint object. The rotation period is just under 12 hours.

Web links

• T. Denk's Ymir website with information on the Cassini observations (in English)
• IAUC 7512: S / 2000 S 1 and S / 2000 S 2 October 25, 2000 (discovery)
• MPEC 2000-Y15: S / 2000 S 1, S / 2000 S 2, S / 2000 S 7, S / 2000 S 8, S / 2000 S 9 December 19, 2000 (ephemeris)
• MPEC 2001-T06: S / 2000 S 1, S / 2000 S 2, S / 2000 S 4, S / 2000 S 6, S / 2000 S 12 October 6, 2001 (rediscovery)
• IAUC 8177: Satellites of Jupiter, Saturn, Uranus August 8, 2003 (numbering and naming)

Individual evidence

1. ↑ ^{a b} T. Denk, S. Mottola, F. Tosi, WF Bottke, DP Hamilton (2018): The Irregular Satellites of Saturn. In: Enceladus and the Icy Moons of Saturn , Schenk, PM, Clark, RN, Howett, CJA, Verbiscer, AJ, Waite, JH (eds.), Space Science Series, The University of Arizona Press, Tucson, AZ. Chapter 20, p. 409-434. DOI: 10.2458 / azu_uapress_9780816537075-ch020 .

further inside	Saturn moons	further outside
S / 2004 S 39	Semi- major axis  (km) Ymir 23,040,000	Lodge