exoplanets-rev-2-labels-768

The several thousand planets so far confirmed to be in orbit around other stars -- exoplanets -- fall into four broad categories: large, gas giants, Neptune-like worlds, "super Earths" bigger than Earth but smaller than Neptune, and terrestrial planets in Earth's size range. Within these categories, however, scientists find even more variety. Among the gas giants, for instance, are "hot Jupiters," infernal worlds with tight, star-hugging orbits.