By Andy Sullivan

WASHINGTON (Reuters) - Scientists said on Thursday that they have discovered an unusually large and light planet orbiting a star that could force them to reexamine theories about how planets are formed.

The planet, dubbed HAT-P-1, is roughly one-third larger than Jupiter but only weighs half as much, astronomers with the Harvard-Smithsonian Center for Astrophysics said.

The planet is about one-quarter the density of water, Harvard-Smithsonian fellow Gaspar Bakos in a statement.


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