UH-led team finds Earth-size planet with rocky core
This artist's rendering provided by the Harvard-Smithsonian Center for Astrophysics today shows the planet Kepler-78b, foreground, orbiting less than one million miles from its sun. (AP Photo/Harvard-Smithsonian Center for Astrophysics, David A. Aguilar)
CAPE CANAVERAL, Fla. » Scientists have found a planet way out in the cosmos that’s close in size and content to Earth — an astronomical first.
But hold off on the travel plans. This rocky world is so close to its sun that it’s at least 2,000 degrees hotter than here, almost certainly too hot for life.
Astrophysicists reported today in the journal Nature that the exoplanet Kepler-78b appears to be made of rock and iron just like Earth.
The planet was discovered using data from NASA’s Kepler Space Telescope, then confirmed by the W.M. Keck Observatory on Mauna Kea, according to the University of Hawaii.
The team, led by Dr. Andrew Howard of UH’s Institute for Astronomy, measured the mass of the planet with the Keck Observatory on Mauna Kea. It’s actually a little bigger than Earth and nearly double its mass, or weight.
Kepler-78b is in the Cygnus constellation hundreds of light-years away. Incredibly, it orbits its sun every 8 1/2 hours, a mystery to astronomers who doubt it could have formed or moved that close to a star. They agree the planet will be sucked up by the sun in a few billion years, so its time remaining, astronomically speaking, is short.
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UH officials said several planets the size or mass of Earth have been discovered recently, but this is the first one with both quantities measured.
"When you have both the size and the mass of an object, you can calculate its density, and thereby determine what it is made of," Howard said in a UH news release.
More than 1,000 exoplanets — worlds outside our solar system — have been confirmed so far.
NASA’s Kepler Space Telescope has identified 3,500 more potential candidates. The telescope lost its precise pointing ability earlier this year, and NASA has given up trying to fix it.
Scientific teams in the United States and Switzerland used ground observatories to measure Kepler-78b.
The other members of Howard’s team are Roberto Sanchis-Ojeda of the Massachusetts Institute of Technology, who analyzed data from the Kepler spacecraft to find the planet and calculate its size; Geoffrey Marcy of University of California-Berkeley; John Johnson of Harvard; Debra Fischer of Yale; Benjamin Fulton and Evan Sinukoff (UH-Manoa graduate students); and Jonathan Fortney of UC-Santa Cruz.
