Pole Star - Other Planets

Other Planets

Pole stars of other planets are defined analogously: they are stars that most closely coincide with the projection of the planet's axis of rotation onto the Celestial sphere. Different planets have different pole stars because their axes are oriented differently. (See Poles of astronomical bodies.)

• Alpha Pictoris is the south pole star of Mercury, while Omicron Draconis is the north star.
• Phi Draconis is the closest star to the southern pole of Venus, however Eta¹ Doradus is brighter though not as close.
• Delta Doradus is the south pole star of the Moon.
• Kappa Velorum is only a couple of degrees from the south Celestial pole of Mars. The top two stars in the Northern Cross, Sadr and Deneb, point to the north Celestial pole of Mars.
• Delta Octantis is the south pole star of Saturn.
• Eta Ophiuchi is the north pole star of Uranus and 15 Orionis is its south pole star.
• The north pole of Neptune points to a spot midway between Gamma and Delta Cygni. Its south pole star is Gamma Velorum.

Some asteroids have more than one axis of rotation, possible due to impacts with other bodies. These asteroids tumble in space and have no pole stars. It is possible that a planet could be similarly affected, though unlikely as the much greater mass of a planet and its (usually) spherical shape make it much more unlikely for an impact to create a second axis of rotation.