Neptune orbits much further away from the Sun than the Earth, so its orbit takes much longer. In fact, Neptune takes 164.79 years to orbit around the Sun. That’s almost 165 times longer than Earth takes to orbit the Sun.
Here’s an interesting fact. Neptune was only discovered on September 23, 1846. At the time this article was written (2009), that was only 163 years ago. In other words, since its discovery, Neptune has not even made a single orbit around the Sun.
On July 11, 2011, Neptune will have completed one full orbit around the Sun. Finally, Neptune will be 1 year old.
Just like Earth, Neptune’s axis is tilted away from the Sun’s axis. This means that it experiences seasons as it orbits the Sun. For half of its orbit, Neptune’s northern hemisphere is tilted towards the Sun, and then for the second half of its orbit, its southern hemisphere is tilted towards the Sun. This differential heating creates very powerful winds on Neptune. In fact, Neptune has the strongest sustained winds on the Solar System, with winds measured at 2100 km/hour.
We have also recorded an entire episode of Astronomy Cast just about Neptune. Listen here, Episode 63: Neptune.