YEAR

Year is a four letter word.

Exactly one year ago, Neptune was first discovered and correctly identified as a planet.

One Neptunian year, that is.

Neptune orbits the sun once every 164.8 years, and although Galileo first located it in his telescope in 1612, it took until 1846 for mathematicians to demonstrate that the orbit of Uranus was being influenced by another planet and to work out its location.  On the evening of 23 September, 1846, astronomers at the Berlin Observatory received a letter from French mathematician Urbain Le Verrier describing where he believed the mysterious planet would be.  They found it that very night, very near the exact location he calculated.

It has had quite a year!  A furious debate about what name to give it, nevermind a debate about who actually discovered it.  Discoveries of moons and rings in orbit around the planet - from the first, just 17 days after the planet itself was discovered, to a visit from Voyager 2.  It reigned as the outermost planet until 1930, when Pluto was discovered, then recaptured the title in 1979 when Pluto's orbit took it inside that of Neptune's, only to emerge outside the orbit again in 1999, and finally settling the issue by having Pluto evicted from the list of planets completely in 2006.  (Just as an aside, Pluto will celebrate its first birthday on March 23rd, 2178.  But it will still be a Plutonian Object and not a Planet.)

Happy Birthday, Lord of the Seas.