Sunday, January 4, 2015

speaking of gas giants...Uranus

Uranus, seventh planet from the Sun. It has the third-largest radius and fourth-largest mass in the Solar System. Uranus is similar in composition to Neptune.  Along with Neptune, sometimes called an "ice giant" (prior post).  It has the coldest planetary atmosphere in the Solar System, with a minimum temperature −224 °C.  It has a complex, layered cloud structure, with water thought to make up the lowest clouds, and methane the uppermost layer of clouds.  At 20 a.u. it has an 84 year orbit.  Like other gas giants it spins rapidly, making one revolution in 17 hours.
Uranus has an axial tilt of 98°, so its axis of rotation is approximately parallel with the plane of the Solar System. This gives it bizarre seasonal changes. Combine this extreme tilt with it's 84 year orbit and you get a 21 year "night" at the pole during winter, compared to a 17 hour day at the equator during equinox.  
Like Neptune, there's not much to see visually.  Unlike Neptune, it can be seen with the unaided eye in dark locations.  At high power it can be seen as a small disk rather than a dot.  A slightly more green than Neptune.  A monster telescope or camera might detect several moons (see below), and possibly faint cloud formations.



The Hubble or flyby space craft can detect faint rings.

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