Planet Nine difficult to otherwise explain. "The amount of warp we see is just crazy," she said. "To me, it's the most intriguing evidence for Planet Nine I've run across so far." American astrophysicist Ethan Siegel, who is deeply skeptical of the existence of an undiscovered planet in the Solar System, nevertheless speculates that at least one super-Earth, which have been commonly discovered in other planetary systems but have not been discovered in the Solar System, might have been ejected from the Solar System during a dynamical instability in the early Solar System. Planetary scientist Hal Levison thinks that the chance of
Giant planet Giant planet A giant planet is any massive planet. They are usually primarily composed of low-boiling-point materials (gases or ices), rather than rock or other solid matter, but massive solid planets can also exist. There are four known giant planets in the Solar System: Jupiter, Saturn, Uranus and Neptune. Many extrasolar giant planets have been identified orbiting other stars. Giant planets are also sometimes called jovian planets, after Jupiter ("Jove" being another name for the Roman god "Jupiter"). They are also sometimes known as gas giants. However, many astronomers now apply the latter term only to Jupiter and Saturn, classifying