Happy Birthday! Neptune was discovered 1 Neptunian year ago today in 1846.
12 July, 2011, is exactly one Neptunian year - or 164.79 Earth years - since its discovery on 24 September 1846.
Neptune cannot be seen without a telescope or binoculars and was discovered after astronomers noticed its effect on the orbit of Uranus and calculated its theoretical position.
Neptune is covered by bright blue methane clouds that whip around the globe at speeds measuring more than 1,600 kph.
The distance between Neptune and the Sun, on average, about 4.5 billion km, varies by 101 million km (63 million miles) depending on where the planet is in its orbit.
Neptune has 13 moons.