When you think about stars, you think about burning gas. You may imagine the intense heat of our closest star, the sun. And you would be right--the sun's surface temperature is 10,000 degrees Fahrenheit. However, not all stars are this hot. NASA has discovered certain astral bodies that are much cooler.
In 2010, NASA discovered 14 "brown dwarfs," which were 14 of the coldest stars it had ever found. Then in 2011, it found some that were even cooler. NASA calls these 6 stars "Y-dwarfs." These "Y-dwarfs" are even cooler than the human body.
Scientists designate these cool orbs "failed stars" because they cannot fuse atoms at their core like regular stars. They also gradually fade until their light is no longer visible to the human eye. In order to find them, NASA developed a special infrared telescope and attached it to a satellite.