URANUS - The Seventh Planet
Uranus has a radius 4 times larger than that of the earth and a mass almost 15 times greater. Although Uranus is somewhat larger than the more distant Neptune, it is less massive by about 15 percent. Consequently it has a smaller mean density than Neptune but larger than that of Saturn. Its average density is slightly higher than that of water. In a large telescope the slightly flattened disk is a light apple green in color.
Nearly 3 billion kilometers fro mthe earth, Uranus presents an almost featureless appearance. Although a few atmoshperic features have been reported, none have been confirmed. As with Jupiter and Saturn, we are probably seeing clouds in its atmoshpere rather than a solid surface.
Uranus's rotation has a peculiarity. Its axis is tilted 98 degree to the perpendicular of its orbital plane-that is, it lies on its "side", so that we see it rotate in the reverse direction barely. For Uranus the retrograde rotaation is due to the peculiar icliation of the axis, while for Venus it is true reverse rotation. When its axis is in our line of sight every 42 years (half the sidereal period), we observe either its sunlit northern or southern hemmisphere, while the opposite hemisphere is dark. One-quarter or three quarters of its periodd laterr (21 or 63 years), its axis is at right aangles to our line of sight and we observe both the northern and southern hemispheres.
The two brightest satellites or Uranus, Titania aand Oberon, were discovered by Willim Harschel in 1797, only 6 years after he discovered teh plaet itself. In all, the planet has five known satellites, which are visible in the infrared photograph. All the satellites move in neraly circular orbits that lie clse to the equatorial plane of Uranus, the same plane as the righ system, and well outside the rings. In htese respects Uranus is similar to Saturn, The ring system was accidentally discovered in 1977 from ovbservations from an airborner telescope that was being used to remeasure Uranus's diameter aand study its atmosphere as teh planet passed over a background star. The expectations of future findings produced by such accidental events as the discovery of Uranus's rings contribute to the excitement and allure of science among not only the general public but scientists as well.
Uranus has a radius 4 times larger than that of the earth and a mass almost 15 times greater. Although Uranus is somewhat larger than the more distant Neptune, it is less massive by about 15 percent. Consequently it has a smaller mean density than Neptune but larger than that of Saturn. Its average density is slightly higher than that of water. In a large telescope the slightly flattened disk is a light apple green in color.
Nearly 3 billion kilometers fro mthe earth, Uranus presents an almost featureless appearance. Although a few atmoshperic features have been reported, none have been confirmed. As with Jupiter and Saturn, we are probably seeing clouds in its atmoshpere rather than a solid surface.
Uranus's rotation has a peculiarity. Its axis is tilted 98 degree to the perpendicular of its orbital plane-that is, it lies on its "side", so that we see it rotate in the reverse direction barely. For Uranus the retrograde rotaation is due to the peculiar icliation of the axis, while for Venus it is true reverse rotation. When its axis is in our line of sight every 42 years (half the sidereal period), we observe either its sunlit northern or southern hemmisphere, while the opposite hemisphere is dark. One-quarter or three quarters of its periodd laterr (21 or 63 years), its axis is at right aangles to our line of sight and we observe both the northern and southern hemispheres.
The two brightest satellites or Uranus, Titania aand Oberon, were discovered by Willim Harschel in 1797, only 6 years after he discovered teh plaet itself. In all, the planet has five known satellites, which are visible in the infrared photograph. All the satellites move in neraly circular orbits that lie clse to the equatorial plane of Uranus, the same plane as the righ system, and well outside the rings. In htese respects Uranus is similar to Saturn, The ring system was accidentally discovered in 1977 from ovbservations from an airborner telescope that was being used to remeasure Uranus's diameter aand study its atmosphere as teh planet passed over a background star. The expectations of future findings produced by such accidental events as the discovery of Uranus's rings contribute to the excitement and allure of science among not only the general public but scientists as well.
