This artist's impression of exoplanet Corot-9b, circling its star.
Credit: Instituto de Astrofsica de Canarias
PARIS: Astronomers have found a temperate planet the size of Jupiter that whips around its star at close proximity.
The work is a technical exploit in the field of exoplanets, as planets outside our Solar System are called, they said.
"This is the first [exoplanet] whose properties we can study in depth," said Claire Moutou, one of 60 astronomers who took part in the discovery.
Most exoplanets found are 'hot Jupiters'
More than 400 exoplanets have been spotted since the first came to light in 1995.
To the disappointment of those dreaming of a home from home, none has yet proved to be a small, rocky, watery world like our own.
Instead, most are 'hot Jupiters' - huge gassy balls that are so close to their stars that their surfaces can be scorched to a thousand degrees Celsius (1,800 degrees Fahrenheit) or more.
CoRoT-9 in the constellation Serpens
The new find, named CoRoT-9b after the French orbital telescope that originally spotted it in 2008, takes a little over 95 days to orbit its host star, CoRoT-9, located 1,500 light years away in the constellation of Serpens, the Snake.
By comparison, the planet Mercury takes 88 days to orbit the Sun.
CoRoT-9b, though, is a gas giant with a mass about 80% that of Jupiter and - compared with other such exoplanets - is relatively temperate.
Temp: between 160 and -20°C
It's surface temperature of between 160 and -20°C, according to the research published by the journal Nature.
The big range in estimates stems mainly from uncertainty about the reflectivity of clouds in the planet's upper atmosphere.
CoRoT-9b is one of only 70 exoplanets that have been captured because they happen to transit directly between the star and the telescope, allowing scientists to study it further.
