London, August 7 (ANI): The planet-hunting Kepler space telescope has found its first extrasolar planets, in the form of three alien worlds that had been previously discovered with ground-based telescopes.
According to a report in New Scientist, the finds confirm that Kepler's instruments are sensitive enough to detect Earth-like planets around sun-like stars.
Kepler launched on 6 March with a simple charge: Stare at a swatch of sky for three and a half years, and look for Earths.
The telescope will hunt transiting exoplanets, planets that pass in front of their stars and dim their brightness at regular intervals.
It's focused on a 100-square-degree patch of the Milky Way between the constellations Cygnus and Lyra that contains about 4.5 million stars, 100,000 of which are prime candidates for planets.
In the first 10 days of its calibration period, Kepler collected data on 52,496 stars, three of which were known to have transiting planets.
"We expected to be able to see those instantly from the first data that we took," said project manager Jim Fanson at NASA's Jet Propulsion Laboratory. "Any planet that you can detect from the ground will be very obviously visible to Kepler," he added.
One of these planets, HAT-P-7b, provided some good news that Kepler is indeed sensitive enough to detect alien Earths.
HAT-P-7b is so hot - more than 2300 degrees Celsius - that it radiates its own light.
"That is about the temperature of a glowing red heating element in a stove or toaster," said deputy principal investigator David Koch of NASA's Ames Research Center. "So, the planet is glowing red," he added.
Kepler detects the light emitted by both the sun and the planet. This means it can tell when the planet passes behind the star as well as in front of it.
When the planet is in front, it blocks a bit of the star's brightness; but when the star is in front, the planet's light disappears.
Kepler measured the dip in brightness when HAT-P-7b hid behind its star with extreme precision - more than enough to detect other Earths, according to Koch.
"Kepler is operating at the level required to detect Earth-size planets," according to Koch and colleagues. "The signal from a Sun-Earth analogue will be at a comparable level of statistical significance," they added. (ANI)