NASA says two of its space telescopes have sighted a "brown dwarf" -- a dim, failed star -- that surprisingly is as cold as the North Pole here on Earth.
Brown dwarfs are born in the same was as stars, coalescing from gas clouds, but never gather sufficient mass to ignite nuclear fuel and burn brightly like a star.
Though never reaching star-like temperatures, some are warmer than others -- but the newly discovered dwarf given the unwieldy name of WISE J085510.83-071442.5 is the coldest ever found, with temperatures hovering between minus 9 and minus 54 degrees Fahrenheit.
The coolest brown dwarfs previously discovered were a lot warmer, closer to room temperature.
Discovered by both NASA's Spitzer Space Telescope and its Wide-field Infrared Survey Explorer (WISE,) the brown dwarf is a near neighbor at just slightly more than seven light years from Earth.
Only the three stars of the Alpha Centauri system are closer, scientists say.
"It's very exciting to discover a new neighbor of our solar system that is so close," astronomer Kevin Luhman of Pennsylvania State University said in a release from NASA's Jet Propulsion Laboratory in Pasadena, Calif. "And given its extreme temperature, it should tell us a lot about the atmospheres of planets, which often have similarly cold temperatures."
NASA's infrared Wise instrument was the first to find the brown dwarf. Because of their cool temperatures, they can be difficult to spot with optical telescopes, but the objects' thermal output, even if quite low, will stand out in frequencies of infrared.
Subsequent observations by the Spitzer Space Telescope, also using infrared, allowed astronomers to determine its temperature.
With telescopes peering into the farthest reaches of the universe, it is still surprising to find a new body so close to our own sun, astronomers said.
"It is remarkable that even after many decades of studying the sky, we still do not have a complete inventory of the Sun's nearest neighbors," said Michael Werner, Spitzer scientist at JPL. "This exciting new result demonstrates the power of exploring the universe using new tools, such as the infrared eyes of WISE and Spitzer."
The newly found object has a mass about three to 10 times that of Jupiter, and might even be a Jupiter-like gas planet tossed out of its original star system rather than a brown dwarf, the scientists admit, although the odds favor a brown dwarf because they are so common.
