When they compared the planets to the models, they found “that a significant fraction of their volume – up to half of it – should be made of materials that are lighter than rock but heavier ...

Now, a new hypothesis proposes that a large fraction of dark matter may be bound up inside tight balls the size of Neptune — so-called dark matter planets ... is dark matter made of?

The revelation seems to indicate that the planet formation model favored by scientists may be overly simple. A team led by researchers from Northwestern University in Illinois made this discovery ...

A faraway gas giant planet that's famous for being strangely "puffy" appears to have clouds that are made of tiny bits of sand. The sand likely acts as water does on Earth, falling like rain ...

Two far-off planets are likely made of water, according to research conducted using NASA's Hubble and Spitzer telescopes.The so-called "water worlds" are orbiting a red dwarf star, the smallest ...