Strange planet is blacker than coal

An alien world blacker than coal, the darkest planet known, has been discovered in the galaxy.

Updated: Aug 12, 2011, 13:21 PM IST

Washington: Astronomers have discovered the darkest known exoplanet in the galaxy that is blacker than coal or any planet or moon in our solar system.

The strange world, TrES-2b, is a gas giant the size of Jupiter, rather than a solid, rocky body like Earth or Mars, astronomers said.

It closely orbits the star GSC 03549-02811, located about 750 light years away in the direction of the constellation of Draco the Dragon.

"TrES-2b is considerably less reflective than black acrylic paint, so it`s truly an alien world," David Kipping of the Harvard-Smithsonian Center for Astrophysics said in a press release issued by Britain`s Royal Astronomical Society (RAS).

First spotted five years ago, TrES-2b races around its star at a distance of just five million kilometres (three million miles).

This is scorchingly close when compared to Earth`s 150-million-km (93-million-mile) distance from the Sun and Jupiter`s 778 million kms (483 million miles).

So fierce is the heat that the exoplanet`s atmosphere is cooked to more than 1,000 degrees Celsius (1,800 degrees Fahrenheit).

Signatures from its atmosphere point to the presence of light-absorbing chemicals like vaporised sodium and potassium or titanium oxide.

But none of these substances can explain the planet`s darkness, which is more extreme than any planet or moon in our own Solar System.

"It`s not clear what is responsible for making this planet so extraordinarily dark," said David Spiegel of Princeton University.

"However, it`s not completely pitch black. It`s so hot that it emits a faint red glow, much like a burning ember or the coils on an electric stove."

More than 500 extrasolar planets have been identified since 1995.

TrES-2b, like our Moon, is believed to be locked by gravitational tide, presenting only one face to its star.

The study, published in the RAS journal Monthly Notices, used NASA`s orbiting Kepler spacecraft to make the observations.

Bureau Report