As proof that first impressions can be misleading, one need not look further than Uranus. After the spacecraft Voyager 2 visited Uranus in 1986, it was dubbed “the most boring planet” in the Solar System. But recent photos from the Hubble Telescope reveal that Uranus is not as dull as once imagined.
For one thing, Uranus is the only planet other than Venus with a retrograde (i.e., clockwise) orbit. Unlike the other planets of the solar system, however, Uranus is tilted almost all the way over on its axis. Essentially, it orbits the sun on its side. Astronomers hypothesize that this unusual orientation might be due to a collision with a planet-sized body soon after Uranus was formed.
Because of its unusual axial tilt, each pole gets around 42 years of continuous sunlight, followed by 42 years of darkness. (A year on Uranus is equal to 84 years on Earth). Bizarrely, however, even though the poles receive more sun than the equator, Uranus is – for unknown reasons — hotter at its equator than at its poles.