On July 11th, 2011 Neptune completed its first full orbit since it was discovered in 1846

On July 11th, 2011 Neptune completed its first full orbit since it was discovered in 1846

Neptune is about 4.50 billion km from the Sun, and it completes an orbit every 164.79 years. Since it was discovered in 1846, that means it just completed its first full orbit last year. It was not, however, in the same spot in our sky, because the Earth was in a different position at both times.

Another interesting fact about Neptune is that it has a similar tilt as Earth and Mars, which means that all three planets experience similar seasonal changes. However, because of how much slower Neptune's orbit is, each season lasts about 40 Earth years ! Despite this, Neptune's days are roughly 16 hours.