Forbidden planets: Understanding alien worlds once thought impossible
Source: By Daniel Clery, Science Excerpt: ...The planet hunt accelerated with the launch of NASA’s Kepler spacecraft in 2009, and the 2500 worlds it has discovered added statistical heft to the study of exoplanets—and yet more confusion. Kepler found that the most common type of planet in the galaxy is something between the size of Earth and Neptune—a “super-Earth,” which has no parallel in our solar system and was thought to be almost impossible to make. ...Other planetary systems looked nothing like our orderly solar system, challenging the well-worn theories that had been developed to explain it. ...The traditional model of how stars and their planets form dates back to the 18th century, when scientists proposed that a slowly rotating cloud of dust and gas could collapse under its own gravity. ...This scenario naturally produces a planetary system just like our own: small, rocky planets with thin atmospheres close to the star, a Jupiter-like gas giant just beyond the...