David Shiga writes "The smallest planet ever seen passing in front of its parent star is a strange world of scorching hot ice, astronomers say. The 22-Earth-mass planet has been known since 2004, but recent observations of it passing in front of its parent star have allowed them to learn much more about it. It appears to be made mostly of water, but not in liquid form. The planet orbits so close to its parent star that its surface is a broiling 300 C, keeping any water there in vapor form. Beneath the atmosphere, the water is even hotter, but is at such high pressure because of the planet's large mass that it stays in a solid, "hot ice" form."