Neptune is an ice giant, composed primarily of hydrogen, helium, and methane, with a hot, dense fluid of icy materials above a small rocky core. Neptune has 14 known moons and at least five main rings ...

But Uranus and Neptune don't. Instead ... There are numerous proposals for spacecraft to visit both worlds, and the furthest along is a mission concept called the Uranus Orbiter and Probe.

(It's worth noting that Uranus and Neptune are too faint to see with ... Various interplanetary spacecraft can use the specific positioning of planets to perform gravity assists, effectively ...

Nasa is switching off two science instruments on its long-running twin Voyager spacecraft to save power. The space agency ...