Triton was discovered in 1846 by the British astronomer William Lassell, but much about Neptune’s largest moon still remains a mystery. A flyby by NASA's Voyager 2 spacecraft in 1989 offered a quick ...

Triton returns to the edge of the solar system in search of answers—where did Neptune’s moons really come from? What secrets is Neptune hiding? A cosmic story of capture, identity, and moon-sized ...

Neptune’s large moon Triton may have abandoned an earlier partner to arrive in its unusual orbit around Neptune. Triton is unique among all the large moons in the solar system because it orbits ...

Sub-Neptune exoplanets tend to be much closer to their host star than Earth is to the Sun and are thought to have atmospheres made of steam over layers of an exotic phase of water that behaves like ...

Animation of a steam world’s evolution from formation to very old age (100 million years to 20 billion years). The interior is initially hot, and cools over time. How fast the planet cools is ...