Planet Neptune - know its facts

Neptune — the blue coloured eighth planet of the solar system, will this year complete its first revolution (in 2011) of the sun since its discovery in 1846.

Neptune has 14 satellites, and a thin ring system that was discovered in 1984. The planet’s orbit is nearly circular.

It’s atmosphere is dominantly hydrogen (80 per cent), with helium (19 per cent) and methane (1 per cent), and a very small admixture of other compounds. 

The average temperature is — 235degrees C. It is 38.87 times bigger and 17.132 times more massive than the Earth.

Neptune is also the first planet found by mathematical prediction rather than by observation. Unexplained deviations in the orbit of the planet Uranus, ever since its accidental discovery on March 13, 1781 by William Herschel, led astronomers to believe that there was some unknown body farther out.

The planet was discovered on September 23, 1846 by Johann Galle and Heinrich d’Arrest from Berlin Observatory very near the predicted position.