Scientists issue weather forecast for alien planet

Scientists have issued the first weather forecast for an alien “super-Earth” orbiting a star 40 light years away.

They are pretty certain it’s going to remain cloudy and hot on the planet GJ 1214b for the foreseeable future.

The world orbits very close to its “red dwarf” parent star, raising temperatures to 232C.

Using the Hubble Space Telescope to study light filtering through the planet’s atmosphere, US astronomers determined that it is shrouded by high-altitude clouds.

What they are made of is still unknown, but computer simulations suggest they could be composed of potassium chloride or zinc sulphide dust. Earlier studies of the planet were not able to tell whether it had clear or cloudy skies.

Now scientists are confident it is both hot and permanently overcast — a little like Venus. As was the case with Venus until the era of space probes, the cloud cover makes it impossible to know what the planet’s surface is like.

Super-Earths, planets having a mass between that of the Earth and Neptune, are believed to be among the most common in our galaxy, the Milky Way. GJ 1214b, whose star lies in the constellation Ophiuchus, is roughly 2.7 times larger than the Earth.

Dr Jacob Bean, leader of the University of Chicago astronomers — whose results appear in the journal Nature — said: “I think it’s very exciting that we can use a telescope like Hubble that was never designed with this in mind, do these kinds of observations with such exquisite precision, and really nail down some property of a small planet orbiting a distant star.”

The observations took up 96 hours of Hubble Telescope time spread over 11 months.

Writing in Nature, the scientists described the findings as an important milestone on the way to identifying potentially habitable Earth-like planets among the stars.