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Space Station Info :: Nine Planet Solar System :: History of Uranus :: Physical Characteristics Of Uranus

Physical Characteristics Of Uranus


Uranus is mainly composed of rocks and various ices, with only about 15% hydrogen and a little helium. Uranus (like Neptune) is analogous to the cores of Jupiter and Saturn minus the substantial liquid metallic hydrogen envelope. It seems that Uranus does not have a hard core like Jupiter and Saturn however that its material is more or less equally dispersed. Uranus' cyan color is due to the absorption of red light by atmospheric methane.

Axial Tilt

Physical Characteristics Of Uranus

One of the most typical features of Uranus is its axial tilt of ninety-eight degrees. As a result, for part of its orbit one pole faces the Sun frequently even as the other pole faces away. At the alternative side of Uranus' orbit the orientation of the poles towards the Sun is reversed. Between these two extremes of its orbit the Sun rises and sets around the equator usually.

At the time of Voyager 2's passage in 1986, Uranus' south pole was pointed about directly at the Sun. Uranus can either be described as having an axial tilt of slightly more than 90, or it can be described as having an axial tilt of some what less than 90 and rotating in a retrograde direction; these two descriptions are exactly correspondent as physical descriptions of the planet but result in different definitions of which pole is the North Pole and which is the South Pole.

Magnetic Field

Uranus' magnetic field is peculiar in that it is not centered on the center of the planet and is tilted about 60 with respect to the axis of rotation. It is perhaps generated by motion at relatively shallow depths within Uranus. Neptune likewise has a displaced magnetic field, suggesting that this is not necessarily a result of Uranus' axial tilt. The magnetotail is twisted by the planet's rotation into a long corkscrew shape behind the planet. The magnetic field's source is unknown; the electrically conductive, super-pressurized ocean of water and ammonia once thought to lie between the core and the atmosphere now appears to be nonexistent.

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