Neptune has just completed its first orbit around the sun since its discovery on September 23rd 1846. With the planet being 2.8 billion miles from the sun that’s an astonishing 165 years to do a full orbit.
Neptune is the first planet to be discovered using mathematics. French astronomer Urbain Le Verrier noticed irregularities in the motions of other planets, and from these perturbations he calculated that there must be an 8th planet lurking out beyond Uranus.
We know there are 13 moons which orbit Neptune, with the largest being Triton, but little else is know about the planet as it has only been photographed once close range, on the Voyager 2 mission in 1989. A future mission to Neptune – The Neptune Orbiter Mission has been removed from the official NASA mission list.
Neptune will be returning to the exact point in its orbit where it was first discovered, just north of Saturn in the constellation Aquarius.
It is back in Aquarius tonight at 22:27 Universal Time (GMT).