Neptune Completes First Orbit Since Discovery In 1846

This illustration is a composite of numerous separate Hubble WFC3 images. 

A colour image composed of exposures made through three color filters shows the disk of Neptune, revealing clouds in its atmosphere. 

48 separate images from a single filter were brightened to reveal the very faint moons. The white dots are Neptune's inner moons moving along their orbits during Hubble's observations. 

The solid green lines trace the full orbit of each moon. Note in this image Triton position and size is not shown to scale. 

The spacing of the moon images follows the timing of each Hubble exposure. About 30 moons are known to orbit Neptune, most of which are too faint or orbit too far away to appear in these images.

Illustration credit: NASA, ESA, and Z. Levay (STScI).

Neptune has arrived at the same location in space where it was discovered nearly 165 years ago. To commemorate the event, NASA's Hubble Space Telescope has taken these "anniversary pictures" of the blue-green giant planet.

Neptune is the most distant major planet in our solar system. German astronomer Johann Galle discovered the planet on September 23, 1846. At the time, the discovery doubled the size of the known solar system.

The planet is 2.8 billion miles (4.5 billion kilometers) from the Sun, 30 times farther than Earth. Under the Sun's weak pull at that distance, Neptune plods along in its huge orbit, slowly completing one revolution approximately every 165 years.