Neptune and its smallest moon Hippocamp (artist's impression)

This artist's impression shows the outermost planet of the Solar System, Neptune, and its small moon Hippocamp. Hippocamp was discovered in images taken with the NASA/ESA Hubble Space Telescope.

Whilst the images taken with Hubble allowed astronomers to discover the moon and also to measure its diameter, about 34 kilometres, these images do not allow us to see surface structures.

Full story: Hubble helps uncover origin of Neptune's smallest moon Hippocamp