Kepler K2-33b, Youngest Exoplanet Found Yet, Shows How Planets Form

Astronomers using NASA's Kepler Space Telescope found a new infant planet, dubbed K2-33b, which may provide clues as to how planets form.

The planet is roughly the size of Neptune, about 5 million to 10 million years old, and about 10 times closer to its star than Mercury is to our sun, orbiting about once every five days, NASA said in a news release.

All told, astronomers have confirmed about 3,000 planets orbiting stars beyond our solar system, which are known as exoplanets. K2-33b's significance is its youth. Earth is about 4.5 billion years old — many times older than K2-33b.

"The newborn planet will help us better understand how planets form, which is important for understanding the processes that led to the formation of Earth," said Erik Petigura of Caltech, co-author of a new study published Monday in the journal Nature.

K2-33b is the second young "hot Jupiter" found in recent months, the Los Angeles Times reported. A hot Jupiter is a gas giant orbiting close to its star. The other one, discovered orbiting a 2 million-year-old star named V830 Tau, was written about in a separate article published in the journal Nature.

The two stars together offer many clues as to how the mysterious gas giants form. Scientists think such planets form farther away from their sun and then are pulled closer in, for example. Another theory says these planets can form in place, or "in situ."

"After the first discoveries of massive exoplanets on close orbits about 20 years ago, it was immediately suggested that they could absolutely not have formed there, but in the past several years, some momentum has grown for in situ formation theories, so the idea is not as wild as it once seemed," Trevor David, a Caltech graduate student working with astronomer Lynne Hillenbrand, said in the NASA release.

"The question we are answering is: Did those planets take a long time to get into those hot orbits, or could they have been there from a very early stage? We are saying, at least in this one case, that they can indeed be there at a very early stage," he said.

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