he tally of confirmed and "candidate" planets grows every day. Just a year and a half into Kepler's planet-hunting mission, there are 28 confirmed planets and 2,326 candidate planets -- of which a stunning 1,000 have been found since February.
Of the 54 "habitable" zone planet candidates seen so far, Kepler-22b is the first to be confirmed. This milestone will be published in The Astrophysical Journal.
The powerful telescopes are finding other things, too. In another big announcement on Monday, using telescopes at the Hawaii-based Keck Observatory and the McDonald Observatory in Texas, astronomers at UC-Berkeley announced the discovery of the largest black holes to date -- two monsters with masses equivalent to 10 billion suns that are capable of consuming anything, even light, within a region five times the size of our solar system.
The $600 million Kepler spacecraft peers at about 150,000 stars in the constellations Cygnus and Lyra, trying to detect any change in star brightness that suggests a passing planet. Three dips, or dimming, must be seen for confirmation.
The Kepler science team uses ground-based telescopes and the Spitzer Space Telescope to review observations on planet candidates that the spacecraft finds, validating their identify.
"The tremendous growth in the number of Earth-size candidates tells us that we're honing in on the planets Kepler was designed to detect: those that are not only Earth-size, but also are potentially habitable," said Natalie Batalha, Kepler deputy science team lead at San Jose State University.
"The more data we collect, the keener our eye for finding the smallest planets out at longer orbital periods," she said.
The planet, named Kepler-22b, is 2.4 times wider than Earth.
But the true nature of the new planet remains a mystery. No one knows whether it's rocky, gaseous or liquid.
If it has a surface, astronomers estimate temperatures in the comfy 70-degree range -- T shirt weather.