Neptune

Neptune is the eighth and farthest planet from the Sun. It takes about 165 Earth years to go round the Sun once. It was discovered in 1846, and in 2011 it finally returned to roughly the spot where it had been when it was discovered, completing its first full orbit since anyone knew it was there.^[1] Its first birthday, as astronomers call it, was attended by nobody who had been at its discovery.

Discovery

Neptune was the first planet found by mathematics before it was seen. Astronomers noticed that Uranus was not quite following its predicted path, and the French mathematician Urbain Le Verrier calculated where an unseen planet would have to be to pull it off course. In September 1846 the German astronomer Johann Galle looked where Le Verrier said and found Neptune within a degree or so of the prediction.^[2]

It is the only planet that was found by someone being told where to look, which is how most people find their keys.

Weather

Neptune has the strongest winds of any planet in the Solar System, reaching around 2,000 kilometres an hour. Its deep blue colour comes from methane in its atmosphere. There is, in other words, a great deal of wind on a very blue planet that nobody can visit, a combination that astronomers say is just as well.

• One Neptune year: ~165 Earth years.
• One Neptune day: ~16 hours.
• Years completed since discovery: one (as of 2011).

See also

• Venus – a planet with a long day
• Blue – its colour
• Wind – which it has the most of

References

1. Leverage, U. (1846). Look Over There. Fictional reprint.
2. Orbit, H. B. (2011). “Happy Birthday, Neptune”. Astronomical Occasions 165: 1.
3. Gale, G. (2003). Two Thousand Kilometres an Hour. Windy Books.