A large number of worlds found by NASA's Kepler alien planet-hunting space telescope are probably significantly larger than scientists previously estimated, a new study suggests. Using a galaxy similar to our own Milky Way, the image above shows the scale of the distances for the sample of stars with planet candidates described in a new study by scientists using the Kitt Peak National Observatory Mayall 4-meter telescope . The circled dot represents the position of the sun in the Milky Way, and the stippled cone shows how far away the new candidate stars are (2800-7000 light years), compared to the size of our galaxy.
The Kepler satellite, in orbit around the sun, stares at a region of the northern hemisphere sky sandwiched between the bright stars Vega and Deneb. Attached to the telescope is the largest imaging camera ever flown into space—16 million pixels—the only instrument on the telescope and the one used to monitor all the stars in its search for planets. Planets are detected if they pass in front of their parent sun, causing a very slight dip in the star’s brightness. When this dip repeats periodically, it reveals the presence of a possible planet, the length of the planet’s “year”, and other information.
"One of the main findings of this initial work is that our observations indicate that most of the stars we observed are slightly larger than previously thought and one quarter of them are at least 35 percent larger," astronomer and leader of the study Mark Everett said in a statement. "Therefore, any planets orbiting these stars must be larger and hotter as well. By implication, these new results reduce the number of candidate Earth-size planet analogues detected by Kepler."
The Daily Galaxy via http://www.noao.edu/news/2013/pr1305.php, Physorg.com, and Space.com
Image credits: NASA, NOAO/AURA/NSF