BBC: The smallest-known planet outside our Solar System, Corot-7b, probably began as a Saturn-sized “gas giant” planet, say researchers. They say the planet, which orbits at one-sixtieth the distance from the Earth to the Sun, has had much of its mass boiled away by the star’s heat. The team also suggests that, if its orbit is not exactly circular, Corot-7b is a hotbed of volcanic activity. The research was presented at the 215th American Astronomical Society …