In 1953, Fritz Leiber published The Wanderer, about a planet that moved through interstellar space, without a sun to orbit. Scientists have now announced the discovery of PSO J318.5-22, a gas giant located 80 light years from Earth that does not orbit a primary. With only six times the mass of Jupiter, the planet is believed to be 12 million years old, relatively young for a planet. The lack of a primary makes it easier for scientists to study the planet.
Scientists have discovered a planet only slightly larger than Earth in orbit around Alpha Centauri, only 4.37 light years from Earth (only Proxima Centauri is closer). The planet, which was discovered based on fluctuations in the star’s movement, orbits closer to its primary than Mercury does and completes an orbit every three days. The discovery was made using data from La Silla Observatory in Chile and will be officially announced in Nature on October 17.
Astronomers have discovered the most hospitable exoplanet yet found orbiting the star Gliese 581, about 20 light years from Earth. The new planet has been named Gliese 581g, one of two additional planets discovered orbiting Gliese 581, brings that star’s system to six planets. Gliese 581g has a mass between 3 and 4 times that of Earth and orbits in the middle of the star’s habitable zone. The planet is believed to be tidally locked to its primary.