Friday, Sept. 23, 2011
THEN On Sept. 23, 1864, Johann Gottfried Galle of the Berlin Observatory searches the night sky for an eighth planet—and finds it! The location of the planet had been calculated earlier by Britain’s John Couch Adams and France’s Urbain Le Verrier independently of each other. The study of Uranus’s orbit had led several astronomers to suspect that it was being affected by the gravity of an eighth planet. On Sept. 23, Galle locates this eighth planet within just one degree of where Le Verrier’s calculations said it would be. The international community of astronomers agrees that Le Verrier and Adams should share credit for the discovery of this planet, Neptune. NOW Last week European astronomers announced the discovery of a super-Earth, a planet 3.6 times more massive than Earth, but residing within a habitable distance from its parent star, which means that temperatures on the planet allow liquid water to exist. The planet’s parent star is too cool, but the discovery offers hope of finding a planet with the conditions to support life. This super-Earth is only one of 55 new planets outside our solar system discovered recently. Among them, 19 are known as super-Earths, so called because they are between a few times and 10 times the mass of Earth. The discoveries were presented last Monday, Sept. 12, at the Extreme Solar Systems II conference in Jackson Lake, Wyo., by Michel Mayor of the University of Geneva in Switzerland. The discoveries were made at the European Southern Observatory (ESO) at Cerro La Silla in northern Chile. It was the High Accuracy Radial velocity Planet Searcher, known as HARPS, that made the discoveries possible. HARPS is able to detect the minute wobbles of stars, which are caused by the gravity of orbiting planets.
