Neptune is the fourth giant planet, much farther than the first ones and therefore more difficult to observe from Earth. This is a gas planet whose composition is mainly made of hydrogen with water inside.
Neptune is also surrounded by rings. They are very thin, irregular, and we thought first that we were in the presence of incomplete arcs.
Click hereafter for animations :
- rotation of Neptune as seen by Voyager (credit : NASA)
- rotation of Neptune as seen by the HST (credit : STScI)