Astronomers Find New Planet 352 Light-Years Away
December 2, 2011

Astronomers Find New Planet 352 Light-Years Away

A team of more than 65 astronomers, including those working at the National Optical Astronomy Observatory (NOAO) and NASA, discovered a new planet nearly the size of Earth, NOAO announced on Wednesday.

The planet, Kepler-21b, was found circling a star about 352 light years away. “By astronomical standards, that´s right next door,” Katy Garmany, the Deputy Press Officer at the NOAO, told Huffington Post.

The research team, led by Steve Howell of NASA Ames Research Center, has shown that Kepler-21b is about 1.6 times that of Earth´s radius and has a mass about 10 times greater. The planet orbit´s an extremely bright star at about 3.75 million miles away. It circles its star about once every 2.8 days.

With such a short period, and such a bright star, the team needed multiple telescopes on the ground to support and confirm the planet´s existence. These included the 4 meter Mayall telescope and the WIYN telescope at Kitt Peak National Observatory.

When comparing Kepler-21b to our Sun´s closest planet, Mercury, a pretty grim picture is painted. Mercury is more than 35 million miles away from the Sun. So, based on that evidence, Kepler-21b would be far hotter than Mercury, and could never sustain life as we know it.

The team calculated that the temperature on the surface of Kepler-21b is about 2,960 degrees Fahrenheit, nowhere near the habitable zone in which liquid water might be found.

Astronomers frequently discover new planets -- more than 2,000, according to Time Magazine -- but Garmany said what is exciting about Kepler-21b is that it is relatively the same size as Earth.

“Until a few years ago, the smallest extra-solar planet that we had discovered was the size of Jupiter or Saturn, which are about ten times bigger than the Earth,” Garmany told the American news website. “Now we´re getting down to something almost the size of the Earth, showing that we have the technology to find the earth-size planets.”

Kepler´s host star, HD 179070, is just a bit bigger and hotter than our Sun, although it is much younger. Its mass is 1.3 solar masses, it has a radius of 1.9 solar radii, and based on stellar models, its age is 2.84 billion years old -- our Sun is 4.6 billion years old. While HD 179070 is relatively close to us in astronomical standards, it cannot be viewed by the naked eye. However, a small telescope could easily pick it out.

Phil Plait, the Bad Astronomer, wrote in Discover Magazine that researchers carried out their studies and examinations of Kepler-21b for 15 months before making their findings public.

The results of their study will be published in Astrophysical Journal, a peer-reviewed journal covering astronomy and astrophysics.


Image Caption: The Kepler field as seen in the sky over Kitt Peak National Observatory. The approximate position of HD 179070 is indicated by the circle (sky imaged using a diffraction grating to show spectra of brighter stars, credit J. Glaspey; telescopes imaged separately and combined, credit P. Marenfeld)


On the Net: