Trick or Treat! Uranus at Opposition on Halloween
Uranus is the third largest planet after Jupiter and Saturn. Its atmosphere is mostly hydrogen and helium, but a small amount of methane present tints the globe a pretty shade of aqua. NASA images We used Mars last week to point to the pulsating, red giant Mira in the constellation Cetus. Today we'll use it again, this time to direct us to Uranus. At Uranus we find ourselves in the cold, abysmal realm of the outer solar system far from Saturn's familiar rings and Jupiter's belted globe. The seventh planet lies more than 1.7 billion miles (2.8 billion km) from the cozy Earth this month. Although nearly four times as large as our planet, Uranus's great distance makes it too faint for most of us to see without optical aid. But if you're going to spot it, now's the time to look — Uranus comes closest to the Earth at opposition which occurs on Halloween this year. This diagram shows the apparent size of the sun in fractions of a degree as seen from the eight plane