Tue July 12, 2011
For Neptune, It's Been One Year Since Its Discovery
It's sentences like these that put the size of the universe in context:
Today, Neptune has arrived at the same location in space where it was discovered nearly 165 years ago.
That comes from the Hubble Space Telescope site and it means that it takes Neptune 165 Earth years to make one trip around the sun. German astronomer Johann Galle discovered the planet in 1846.
So, in honor of Neptune's first anniversary, NASA has released four new images of the planet. Here's an explanation of the images at the top of this post:
The snapshots show that Neptune has more clouds than a few years ago, when most of the clouds were in the southern hemisphere. These Hubble views reveal that the cloud activity is shifting to the northern hemisphere. It is early summer in the southern hemisphere and winter in the northern hemisphere.
In the Hubble images, absorption of red light by methane in Neptune's atmosphere gives the planet its distinctive aqua color. The clouds are tinted pink because they are reflecting near-infrared light.
A faint, dark band near the bottom of the southern hemisphere is probably caused by a decrease in the hazes in the atmosphere that scatter blue light. The band was imaged by NASA's Voyager 2 spacecraft in 1989, and may be tied to circumpolar circulation created by high-velocity winds in that region.
And one more interesting fact about Neptune: Like Earth it is tilted so it experiences seasons, but each season lasts about 40 years.