Bestla or Saturn XXXIX is a retrograde irregular moon of Saturn. Its discovery was announced by Scott S. Sheppard, David C. Jewitt, Jan Kleyna, and Brian G. Marsden on 4 May 2005, from observations taken between 13 December 2004 and 5 March 2005.

Description

Bestla is about 7 kilometres in diameter, and orbits Saturn at an average distance of 20,337,900 km in 1087 days, at an inclination of 136° to the ecliptic, in a retrograde direction and with an eccentricity of 0.461. Early observations from 2005 suggested that Bestla had a very high eccentricity of 0.77. Like many of the outer irregular moons of the giant planets, Bestla's eccentricity may vary as a result of the Kozai mechanism. Bestla rotates in a retrograde direction and makes a full rotation every 14.624 hours. Like Kiviuq, it is likely to be a contact binary or binary object, as its light curve has strong variation in brightness and a plateau-like maximum not seen in the other irregulars.

Name

This moon was named in April 2007 after Bestla, a frost giantess from Norse mythology, who is a mother of Odin.