Thyone (pron.: // thy-OH-nee; Greek: Θυώνη), also known as Jupiter XXIX, is a retrograde irregular satellite of Jupiter. It was discovered by a team of astronomers from the University of Hawaii led by Scott S. Sheppard, et al. in 2001, and given the temporary designation S/2001 J 2.
Thyone is about 4 kilometres in diameter, and orbits Jupiter at an average distance of 21,406 Mm in 639.803 days, at an inclination of 147° to the ecliptic (147° to Jupiter's equator) with an eccentricity of 0.2526.
Thyone belongs to the Ananke group, retrograde irregular moons which orbit Jupiter between 19.3 and 22.7 Gm, at inclinations of roughly 150°.