NASA discovers the sun has an icy neighbor

NASA's Wide-field Infrared Survey Explorer (WISE) and Spitzer Space Telescope have found what appears to be a brown dwarf, or star-like object, that is as cold as the North Pole, just 7.2 light-years away from the sun.

The closest solar system to the sun is Alpha Centauri, about 4 light-years away.

"It is very exciting to discover a new neighbor of our solar system that is so close," Kevin Luhman, an astronomer at Pennsylvania State University's Center for Exoplanets and Habitable Worlds, said in a statement. "And given its extreme temperature, it should tell us a lot about the atmosphere of planets, which often have similarly cold temperatures."

Brown dwarfs begin as collapsing balls of gas, just like any other star, but they do not have enough mass to sustain nuclear fusion. This new brown dwarf — named WISE J085510.83-071442.5 — was found after WISE surveyed the entire sky at least twice using infrared light (NASA says that cooler objects stand out in infrared light because it captures their thermal glow). It is between -54 and 9 degrees Fahrenheit, which is much colder than the other brown dwarfs discovered by WISE and Spitzer, thought to be around room temperature.

"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," Michael Werner, Spitzer's project scientist at the Jet Propulsion Lab, said in a statement. "This exciting new result demonstrates the power of exploring the universe using new tools, such as the infrared eyes of WISE and Spitzer." The animation below, courtesy of NASA/JPL-Caltech/Penn State, shows how the brown dwarf was spotted, thanks to its rapid motion across the sky. --Catherine Garcia

NASA discovers the sun has an icy neighbor