Scientists have discovered an unusually large and light planet orbiting a star that could force them to re-examine theories about how planets are formed.
The planet, dubbed HAT-P-1, is roughly one-third larger than Jupiter but weighs only half as much, astronomers with the Harvard-Smithsonian Center for Astrophysics said Thursday.
The planet is about one-quarter the density of water, Harvard-Smithsonian fellow Gaspar Bakos in a statement. “It’s lighter than a giant ball of cork,” he said.
HAT-P-1 revolves around its parent star once every 4.5 Earth days in an orbit one-seventh of the distance from Mercury to the sun, according to Bakos and other Smithsonian astronomers.
Its parent star, one of a double-star system, is about 450 light-years from Earth. One light-year is about 6 trillion miles or 10 trillion kilometers.
Scientists detected the planet because light from its parent star dims when the planet passes in front of it. Like another planet discovered by this method, HAT-P-1 turned out to be larger than predicted by theory, they said.
“The new discovery suggests something could be missing in our theories of how planets form, or we may have to create a new category for classifying planets,” said Robert Noyes, another astronomer at the Center for Astrophysics.
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Month in Space: January 2014
Scientists said the large size could be the result of heat coming from the interior of the planet, though they have yet to determine how that could happen.
Researchers have discovered about 200 planets outside the solar system in all.
Another group of Smithsonian scientists said they had devised a way to determine if distant planets could harbor life by comparing the main gases in a planet’s atmosphere with the historical makeup of Earth’s atmosphere.
An atmosphere largely composed of methane gas could create a hospitable environment for anaerobic bacteria, as it did on Earth 3.5 billion years ago, they said. The presence of oxygen might mean that more sophisticated life forms could exist.
