Uranus - The Supreme God

Uranus is the seventh planet from the Sun and the third largest (by diameter). Uranus is larger in diameter but smaller in mass than Neptune.

orbit: 2,870,990,000 km (19.218 AU) from Sun
mass: 8.683e25 kg
diameter: 51,118 km
Temperature: -193°C
Composition:
Atmosphere: 83% hydrogen (H), 15% helium (He) and 2% methane.
Rings: Yes
Satellites: 20, 1 recently discovered: Ariel, Belinda, Caliban, Cordelia, Cressida, Desdemona, Juliet, Miranda, Oberon, Ophelia, Portia, Puck, Rosalind, Sycorax, Titania, Umbriel
Year Length: 84 years
Day Length: -17.9 hours (Uranus rotates the opposite way of the earth)
Surface gravity: 7.7 m/s^2 approx. 1/3 of earth's surface gravity.

Uranus has been visited by only one spacecraft, Voyager 2 on Jan 24 1986.

Most of the planets spin on an axis nearly perpendicular to their plane of rotation about the sun, but Uranus' axis is almost parallel to it's plane of rotation. At the time of Voyager 2's passage, Uranus' south pole was pointed almost directly at the Sun. This results in the odd fact that Uranus' polar regions receive more energy input from the Sun than its equatorial regions. Uranus is nevertheless hotter at its equator than at its poles. The mechanism underlying this is unknown.

Uranus is composed primarily of rock and various ices, with only about 15% hydrogen and a little helium (in contrast to Jupiter and Saturn which are mostly hydrogen). Uranus (and Neptune) are in many ways similar to the cores of Jupiter and Saturn minus the massive liquid metallic hydrogen envelope. It appears that Uranus does not have a rocky core like Jupiter and Saturn but rather that its material is more or less uniformly distributed.

Like the other gas planets, Uranus has bands of clouds that blow around rapidly. But they are extremely faint, visible only with radical image enhancement of the Voyager 2 pictures. Recent observations with Hubble Space Telescope(HST) show larger and more pronounced streaks. Further HST observations show even more activity. With the HSPT, it now seems clear that the differences are due to seasonal effects since the Sun is now at a lower Uranian latitude which may cause more pronounced day/night weather effects. By 2007 the Sun will be directly over Uranus's equator.

Like the other gas planets, Uranus has rings. Like Jupiter's, they are very dark, but like Saturn's they are composed of fairly large particles ranging up to 10 meters in diameter in addition to fine dust. There are 11 known rings, all very faint; the brightest is known as the Epsilon ring. The Uranian rings were discovered right after Saturn's rings were discovered. This was of considerable importance since we now know that rings are a common feature of planets, not a peculiarity of Saturn alone.

Uranus is sometimes just barely visible with the unaided eye on a very clear night; it is fairly easy to spot with binoculars (if you know exactly where to look). A small astronomical telescope will show a small disk. There are several Web sites that show the current position of Uranus (and the other planets) in the sky, but much more detailed charts will be required to actually find it.

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