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Last Updated: Friday, 13 October 2006, 12:25 GMT 13:25 UK
'Most distant' weather pictures
Artist's impression of upsilon Andromedae b (Nasa/JPL-CArtist's impression of upsilon Andromedae b (Nasa/JPL-Caltech)
Scientists are keen to understand weather systems on exoplanets
A Nasa space telescope has delivered the first weather forecast from a planet outside our Solar System.

The world, known as Upsilon Andromedae b, orbits close into a star that is 380 trillion km from Earth.

The Spitzer Space Telescope has been able to detect distinct day and night temperatures on the planet.

The results, reported in the journal Science, suggest weather systems transport very little heat from one side of the planet to the other.

This means one face of the planet is blisteringly hot, while the other is frigid in comparison.

"Such a large difference between the day and night sides reveals very interesting things about how heat and air masses flow on the planet. It makes for a very unusual climate and weather on this planet," said co-researcher Dr James Cho from Queen Mary University of London, UK.

Global detail

The models produced thus far by scientists to describe the weather systems on such planets predict there should be very strong winds redistributing heat around the globe.

But Spitzer's measurements suggested atmospheric gases were instead absorbing and re-radiating sunlight rapidly, said study leader Dr Joe Harrington, from the University of Central Florida in Orlando, US.

Nasa's Spitzer infrared telescope

The finding represents the first time that any kind of variation has been seen across the surface of an extrasolar planet (also sometimes called exoplanet).

Previous measurements have described only global traits, such as diameter and mass.

Upsilon Andromedae b was first discovered in 1996 around the star Upsilon Andromedae. It is what is known as a "hot-Jupiter" planet, because it is made of gas like our Jovian giant, and is hot, due to its tight, 4.6-day-long journey around its star.

The planet orbits its star at one-sixth the distance of Mercury from our own Sun.

Since the first planet orbiting another sun-like star was discovered in 1995, more than 200 such objects have been found.

'Bulge' yields new planet class
04 Oct 06 |  Science/Nature
Planets have scientists buzzing
26 Sep 06 |  Science/Nature
Puffy planet poses pretty puzzle
15 Sep 06 |  Science/Nature
A view from the cosmic shoulder
06 Sep 06 |  Science/Nature

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