Hunting Down Alien Planets

Hunting down alien planets

The $600 million Kepler observatory launched in March 2009 to hunt for Earth-size alien planets in the habitable zone of their parent stars, where liquid water, and perhaps even life, might be able to exist.

Photo By HANDOUT/Reuters

Kepler detects alien planets using what's called the "transit method." It searches for tiny, telltale dips in a star's brightness caused when a planet transits — or crosses in front of — the star from Earth's perspective, blocking a fraction of the star's light.

The finds graduate from "candidates" to full-fledged planets after follow-up observations confirm that they're not false alarms. This process, which is usually done with large, ground-based telescopes, can take about a year.

The Kepler team released data from its first 13 months of operation back in February, announcing that the instrument had detected 1,235 planet candidates, including 54 in the habitable zone and 68 that are roughly Earth-size.

Of the total 2,326 candidate planets that Kepler has found to date, 207 are approximately Earth-size. More of them, 680, are a bit larger than our planet, falling into the "super-Earth" category. The total number of candidate planets in the habitable zones of their stars is now 48.

To date, just over two dozen of these potential exoplanets have been confirmed, but Kepler scientists have estimated that at least 80 percent of the instrument's discoveries should end up being the real deal.

ref: http://news.yahoo.com/