Does it mean Neptune is just one year old? No. Every planet has got its different ‘year’ i.e. the time to complete its rotation around the sun. For Neptune the time for one revolution of sun is as long as from the year 1846 to the present year.

Does it again mean that Neptune didn’t revolve around the sun before 1846? No. The year 1846 was the year when the planet was discovered by human beings, the blue colored eighth planet of the solar system.

One question more. How can we say that the revolution just started or completed at any particular moment? This is actually arbitrary. No one saw any planet starting its first revolution of sun. The heavenly body is said to celebrate its birthday on July 13 when it reaches the same heliocentric longitude as that at the time of its discovery. At the moment we came to know of it for the first time we ‘declared’ its birth.

The planet is viewed only with the help of a moderate telescope. You have to see it between the stars Delta Capricorni and Lambda Aquari.

On August 22, 2011 it will be in opposition that means when the sun sets in the west it will rise and will be up all the night. It is also the first planet to be discovered by mathematical calculations before its real observation.

The motion of planet Uranus and deviations in this motion helped ‘calculate’ Neptune’s presence far away.

John Adams and Urbain Le Verrier had predicted in 1845 the mass and orbit of the unknown planet. And in 1846 it was discovered very near the predicted position. The credit to discover it went to Johann Galle and Heinrich d’Arrest, who observed it from Berlin Observatory.

Neptune with a nearly circular orbit has as many as 13 satellites. A thin ring system revolving around it was also discovered in 1984. Its atmosphere predominantly consists of hydrogen (80 percent). The average temperature over the planet is 235 degrees of Celsius. Its volume and mass are over 38 and 17 times greater than that of earth.

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