Kepler follows phases of alien world

A planet-hunting spacecraft has made detailed observations of a world orbiting another star. NASA’s powerful Kepler space telescope scanned the planet’s atmosphere and even deduced changing phases, just like those shown by the Moon.

Artist's impression of Kepler in spaceScientists are thrilled by discovery made during initial tests of instruments on Kepler, which was launched in March. It shows that it should succeed in its mission to discover other rocky worlds like Earth.

It trained its telescope on a star called HAT P-7 on a star 1,000 light-years away in a region of sky that stargazers call the Summer Triangle.

The planet, which had already been found, orbits the star in just 2.2 days and is 26 times closer to it than Earth is to the sun. It resembles Jupiter, the biggest planet in our own solar system, but is so close to its star that it glows like a hot plate on a stove.

NASA revealed the first results today. Kepler’s measurements were so precise that they show a smooth rise and fall in brightness as the planet passed in front of the star as it orbited it.

The data reveals that the planet has an atmosphere with a day-side temperature of 2377 Celsius (4,310 F). Little of this heat is carried to the cool night side. Scientists could even deduce that the planet’s orbit is circular rather than oval.

The occultation time compared to the main transit time shows the planet has a circular orbit. The discovery of light from this planet confirms the predictions by researchers and theoretical models that the emission would be detectable by Kepler.

NASA scientists hope now to fine-tune the instruments on Kepler to make it even more powerful. NASA’s Hubble and Spitzer space telescopes have also previously managed to tell us much about the atmospheres of other worlds.

David Koch, of NASA’s Ames Research Centre in California, said: “This early result shows the Kepler detection system is performing right on the mark. It bodes well for Kepler’s prospects to be able to detect Earth-size planets.”

• Discover space for yourself and do fun science with a telescope. Here is Skymania’s advice on how to choose a telescope. We also have a guide to the different types of telescope available.

Paul Sutherland

Paul Sutherland

I have been a professional journalist for nearly 40 years. I write regularly for science magazines including BBC Sky at Night magazine, BBC Focus, Astronomy Now and Popular Astronomy. I have also authored three books on astronomy and contributed to others.
Paul Sutherland

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Paul Sutherland

I have been a professional journalist for nearly 40 years. I write regularly for science magazines including BBC Sky at Night magazine, BBC Focus, Astronomy Now and Popular Astronomy. I have also authored three books on astronomy and contributed to others.

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