True and false colour images of the planet Uranus taken by Voyager 2. NASA's two Voyager spacecraft were launched in 1977 to explore the planets in the outer solar system. Voyager 2 reached Jupiter 1979 before flying on to Saturn which it reached in 1981. It eventually reached Uranus in 1986 and moved on towards Neptune. Uranus, the 7th planet from the Sun, was discovered by William Herschel in 1781. It is a gas giant planet, with an atmosphere of 83% hydrogen, 15% helium and 2% methane; the latter absorbs red light in the upper atmosphere, giving the planet its blue colour. Like Jupiter and Saturn, Uranus has bands of cloud which circulate rapidly in its atmosphere, but they can only be seen with colour enhancement as in the lower of these images.
© National Aeronautics & Space Administration / Science & Society