Uranus

planet Uranus

Uranus is the seventh furthest planet from our Sun, with a distance of 2875 million km (1787 million miles) from the Sun.

It is similar in size and composition to the planet Neptune, with an equatorial diameter of 51,120 km (31,770 million miles).

It takes Uranus 84 Earth years to make one orbit around the sun and 17.2 hours to make one complete rotation on its axis (Chaisson and McMillan, 2005).

Because Uranus is so far away from Earth, it is hard to see with the naked eye, but not impossible. It can be viewed through a telescope, where it looks like a small blue-green disk, but you can't really make out surface features.

The reason that Uranus appears blue-green to us is because of the methane in its atmosphere. Methane absorbs red and reflects blue.

Similar to Jupiter's atmosphere, the atmosphere on Uranus is mostly hydrogen and helium, with smaller amounts of methane. The more methane present on the planet, the more blue the planet appears. The concentration of methane on Uranus is only about 2 percent, which is why the planet appears blue-green instead of blue (Chaisson and McMillan, 2005).

Unlike the other gas planets, Uranus doesn't appear to have an internal heat source. The other gas planets in our solar system (Jupiter, Saturn, and Neptune) generate more heat than they absorb from the Sun.

Uranus is tilted on its side. Scientists don't know why Uranus is tilted 98 degrees on its axis, but believe that at some point Uranus may have had a collision with a very large object. However, there is no other evidence to suggest that Uranus was hit by a planet sized object, other than its unusual tilt.

Uranus has 27 moons and a much stronger magnetosphere than Earth has.

Uranus rings

Uranus has rings, but they aren't as impressive as Saturn's ring system. In fact, all of the gas planets have rings around them, but none of their ring systems are as impressive as Saturn's rings. There are nine rings around Uranus, but they are darker and less reflective than the rings of Saturn.

Scientists don't know as much about the internal structure of Uranus as they do about some of the other planets, but they believe that Uranus has a rocky core surrounded by water, that is surrounded by molecular hydrogen.

REFERENCES

Chaisson, E. and McMillan, S. (2005). Astronomy Today. Pearson Prentice Hall: Upper Saddle River, NJ.

Image of Uranus and rings of Uranus: Courtesy of NASA/JPL-Caltech.