The Coldest Place in the Universe
![An image of the Boomerang Nebula.](/sites/default/files/styles/large_1/public/2017-07/nrao17cb21a-1170x600.jpg.webp?itok=D2dFJEQ2)
The Boomerang Nebula is the coldest location in the known universe: it measures at roughly 2 degrees colder than empty space! This nebula is the result of the death of a red giant star, and the extreme temperature is caused by the rapid expansion of the nebula. According to thermodynamics, if you expand a gas you, cool a gas (just try using one of those compressed air cans for cleaning electronics). However, according to astronomers, a single star's death could not account for a strong enough wind to create this expansion. Based on this hypothesis, and data from the ALMA observatory, astronomers now believe the expansion of the Boomerang Nebula is being driven by a companion star.