With more than 5,000 exoplanets confirmed, researchers can break them into broad categories. Some 30 percent are gas giants like Jupiter or Saturn; roughly 35 percent are Uranus- or Neptune-like; and just 4 percent are rocky, terrestrial planets like Earth. Many exoplanets (31 percent) are super-Earths or mini-Neptunes, which fall between the mass of Earth and Neptune and may be rocky or support thick, puffy atmospheres. Such planets have no analogue in our solar system.