Astronomers have long called Uranus and Neptune the "ice giants" because models suggested that these outer planets' interiors are largely made of mixtures of water, ammonia and other ices — compounds ...

Uranus and Neptune are the two furthest planets in the Solar System and have been visited only once by human spacecraft – by Voyager 2 over 30 years ago – so there is a lot about them that we do not ...

The planets in the Solar System are typically divided into three categories based on their composition: the four terrestrial rocky planets (Mercury, Venus, Earth and Mars), followed by the two gas ...

Add Yahoo as a preferred source to see more of our stories on Google. When you buy through links on our articles, Future and its syndication partners may earn a commission. A composite image of Uranus ...