An artist’s impression of the new planetoid called Sedna. (AFP)

Washington, March 15 (Reuters): Astronomers have discovered the coldest and most distant object ever found in the solar system, a dark and frigid world a bit smaller than Pluto and three times farther away.

The new “planetoid,” named Sedna after an Inuit goddess who created Arctic sea creatures, is more than 13 billion km from the sun and never gets above minus 240 degrees Celsius, astronomers said yesterday.

“The sun appears so small from that distance that you could completely block it out with the head of a pin,” said Mike Brown, an astronomer at California Institute of Technology, who led the research team. Sedna is one of the reddest objects in the solar system, after Mars, and takes 10,500 years to travel its highly elliptical path around the sun.

Brown and the other astronomers detected Sedna on November 14 during a survey of the outer solar system. As they peered into space, they saw stationary stars and other cosmic bodies, and a very slowly moving object that turned out to be Sedna. “Anything that moves very slowly across the sky, we know it’s something in the solar system: a satellite, a planet, an asteroid,” Brown said. “But this is the most slowly moving object we’ve ever seen moving across the sky.”

As distant and cold as Sedna is now, its orbit around the sun takes it more than 10 times further, to a distance of 135 billion km.