Uranus - Observations From Earth, Results From The Flyby Of The Voyager 2 Spacecraft, Uranus's Magnetic Field - Discovery, Puck
cambridge press university planet
Uranus is the seventh planet from the Sun. It has a large size (its diameter is almost four times that of Earth) and mass, low mean density, fairly rapid rotation, and well-developed ring (11 components) and satellite (15 members) systems. The planet has a strong magnetic field with a large tilt (58.6°) to its rotation axis and offset (0.3 Uranus radius) from its center. Analysis of the observations made by Voyager 2 during its flyby of Neptune in August 1989 shows that Uranus and Neptune are similar in most of these properties and form a subgroup of the Jovian planets; Jupiter and Saturn, much larger and more massive, form the other subgroup.
William Herschel (1738–1822) fortuitously discovered Uranus in 1781; it was the first planet discovered telescopically. It was found to orbit the sun at a mean distance of about 19.2 astronomical units (a.u.) (2,870,000,000 km), about twice as far from the sun as Saturn (9.54 a.u), the most distant planet known before 1781.
Puck's surface was also imaged by Voyager 2, revealing a cratered surface that is considerably darker (0.08 average albedo) than that for any of the five larger satellites. The Voyager 2 images also show that Puck is almost spherical. The three largest impact craters on Puck are named Bogle, Lob, and Butz.
Resources
Books
Beatty, J. Kelly, Carolyn Collins Petersen, and Andrew L. Chaikin. The New Solar System. Cambridge: Cambridge Univ. Press, 1999.
Bergstrahlh, Jay T., Ellis D. Miner, and Mildred S. Matthews, eds. Uranus. Tucson: University of Arizona Press, 1991.
de Pater, Imke and Jack J. Lissauer. Planetary Sciences Cambridge, UK: Cambridge University Press, 2001.
Morrison, D., and Tobias Owen. The Planetary System. 3rd ed. Addison-Wesley Publishing, 2002.
Taylor, F.W. The Cambridge Photographic Guide to the Planets. Cambridge University Press, 2002.
Periodicals
Beatty, J.K. "Voyager 2's Triumph." Sky & Telescope 72, no. 4 (October 1986): 336-342.
Cuzzi, Jeffrey, and Larry Esposito. "The Rings of Uranus." Scientific American (July 1987): 52-66.
Dowling, T. "Big Blue: Twin Worlds of Uranus and Neptune." Astronomy 18, no. 10 (October 1990): 42-53.
Frederick R. West
David T. King, Jr.
Additional Topics
The planes of the orbits of Oberon and Titania were expected to lie in or near the plane of Uranus' equator, since most other planetary satellites have orbital planes that are in or near the equatorial planes of their planets. When the orbital planes of Oberon and Titania were determined, however, they indicated that the plane of Uranus' equator is almost perpendicular to the plane o…
The Voyager 2 spacecraft was launched from Earth on August 20, 1977. As it flew by Jupiter in July 1979, it was accelerated toward Saturn which, in turn, accelerated Voyager 2 toward Uranus during the August 1981 flyby. Voyager 2 flew by Uranus on a hyperbolic orbit, passing it at a minimum distance of 66,447 mi (107,000 km) from the center of Uranus on January 24, 1986. The observations that Voya…
Like Earth and the other Jovian planets, Uranus has a strong magnetic field which arises in its interior. Evidence for Uranus' magnetic field and magnetosphere (the region of space where the planet's magnetic field is dominant over the interplanetary field) was not found until January 22, 1986, two days before closest approach to Uranus, when radio noise from charged particles trappe…
In the earlier discussion of Uranus' seasons, it was mentioned that a unit surface at the poles will receive about 1.5 times as much sunlight as the same surface would on Uranus equator over a Uranian year. Based on this, one might expect Uranus' south polar region, which at the time of the Voyager 2 flyby had been in continuous sunlight for the order of 20 years, to be warmer than i…
By solar and stellar occultations and visual, infrared, and radio observations from Voyager 2, the structure and circulation of Uranus' atmosphere has been mapped from just below the cloud layers to its exosphere. The main components of the atmosphere are hydrogen and helium, the most abundant elements in the universe. Methane comprises 1–2% of the observable troposphere. Water vapor…
Uranus' ring particles are dark grey to black and form rings about 1–37 mi (2–60 km) wide and less than one kilometer thick. The rings are in the equatorial plane of Uranus, which is tilted at 98 degrees to the typical planetary attitude of the solar system (i.e., the plane of the orbit of the inner eight planets). This suggests that the rings formed after the planet was title…
Uranus' satellites all lie in the equatorial plane (like the rings). There are several groups of satellites. The inner satellites, of which there are ten, are irregular dark
Figure 2. Diagram of offset and tilted magnetic field of Uranus. Illustration by Hans & Cassidy. Courtesy of Gale Group.
objects (which may mean they are carbonaceous rock or are methane ice bodies coated w…
Voyager 2 obtained detailed images of parts of the sunlit surface of all five previously known satellites and also of Puck. Bright and dark (albedo) regions, craters with or without bright ray systems around them, mountains, cliffs, scarps, valleys, canyons, graben, faults, and other geological features are clearly seen on these images. Maps of the parts of the satellite surfaces that have been im…
Titania, Uranus' largest and most massive satellite, shows similar geological features to those found on Oberon. Heavily cratered plains are the most extensive surfaces found here. Oberon also shows a global rift valley network related to global tectonics. Image resolution is somewhat better for Titania than Oberon, since Voyager 2 was closer to Titania. A prominent system of canyons and sc…
Ariel is similar in size and mass to Umbriel, but whereas Umbriel is the darkest of Uranus' five largest
Unlike the other gas giants, Uranus reveals few atmospheric features in visible light. However, latitudinal atmospheric bands do exist, as can be seen in the enhanced image on the right; because Uranus has such an inclined axis of rotation (which is pointing almost directly down into …
Miranda shows the most interesting evidence for geologic activity and surface modification among Uranus' satellites. In addition to old cratered plains, canyons, scarps, lineaments, and valleys, the three coronae Arden, Elsinore, and Inverness exist on its surface; they are its most prominent surface features. They are large, lightly cratered regions of up to 186 mi (300 km) or more extent;…
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