Astronomy Uranus Was the First Planet Discovered

Astronomy

Uranus

Uranus was the first planet discovered in contemporary times. It was discovered in 1781 by William Herschel while he was searching the sky with his telescope. It had actually been seen many times before but ignored as simply being another star. "In the beginning Herschel named it "the Georgium Sidus" (the Georgian Planet) in honor King George III of England. Others called it "Herschel." The name "Uranus" was first proposed by Bode in conformity with the other planetary names from classical mythology but didn't come into common use until 1850" (Uranus, 2011).

The only spacecraft to ever visit Uranus was Voyager 2 in 1986. Uranus is different in that most of the planets spin on an axis almost perpendicular to the plane of the ecliptic but Uranus' axis is almost parallel to the ecliptic. At the time of Voyager 2's passage, Uranus' South Pole was pointed almost directly towards the Sun. This results in the odd fact that Uranus' Polar Regions receive more energy input from the Sun than do its equatorial regions. Uranus is nonetheless hotter at its equator than at its poles and the reason for this is currently unknown (Uranus, 2011).

There has been a continuing dispute over which of Uranus' poles is its north pole. "Either its axial inclination is a bit over 90 degrees and its rotation is direct, or it's a bit less than 90 degrees and the rotation is retrograde. The issue is that one needs to draw a dividing line somewhere, because in a case like Venus there is little argument that the rotation is indeed not a direct rotation with an inclination of nearly 180 degrees" (Uranus, 2011).

Uranus is the seventh planet from the Sun and the third largest in diameter. It is made up mainly of rock and various ices, with only about fifteen percent hydrogen and very little helium. This is in direct contrast to Jupiter and Saturn which are made up mostly of hydrogen. Uranus and Neptune are in a lot of ways similar to the cores of Jupiter and Saturn less 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 homogeneously dispersed (Uranus, Seventh Planet in Earth's Solar System Was First Discovered Planet, 2011).

Just like the other gas planets, Uranus has bands of clouds that blow around quickly. But they are exceptionally faint. Some observations done with HST have shown larger and more pronounced streaks. Further HST observations show even more activity. Uranus is no longer the very boring planet that Voyager saw twenty five years ago. It has been discovered that the dissimilarities seen are due to seasonal effects since the Sun is now at lower latitude. This is thought to cause more pronounced days and nights along with weather effects. Uranus' blue color is the consequence of absorption of red light by methane in the upper atmosphere. It is thought that there may be colored bands like Jupiter's but they are hidden from view by the overlaying methane layer (Uranus, 2011).