The 0.95-m-diameter Kepler telescope—a photometer—was launched into an Earth-trailing heliocentric orbit on March 6 to detect Earth-size exoplanets. It stares at the same patch of sky, monitoring the brightness of about 100,000 stars, searching for planetary occultations. Now, researchers from NASA and 12 other institutions have tested Kepler on an already known exoplanet 1044 light years away, the gas giant HAT-P-7b, detecting its atmosphere. The data show the transit (the planet passing in front of the star), the occultation (the planet passing behind the star), and the phase change of the planet as it orbits (similar to the waxing and waning of the Moon as seen from Earth).
Without the need for systematic error correction, the occultation and phase-change data confirm the prediction of a theoretical model showing a strongly absorbing planetary atmosphere, along with inhibited transport of the atmosphere to the nightside of the planet. HAT-P-7b has an orbital period of 2.2 days and an estimated dayside temperature of 2650 K. The data indicate that Kepler is sensitive enough to detect an Earth-sized planet in an Earth-like orbit around a 12th-magnitude star. Contact William Borucki at [email protected].