The Boomerang Nebula is the coldest known natural place in the universe.

The Boomerang Nebula is a young planetary nebula located in the constellation Centaurus. It was first observed in detail using the Anglo-Australian Telescope in 1980 by astronomers Keith Taylor and Mike Scarrott. They noticed its asymmetrical shape, which resembles a boomerang, though later high-resolution images from the Hubble Space Telescope in 1998 revealed a structure more like a bow tie.The nebula's extreme cold is the result of a process called adiabatic expansion. As the central star dies, it ejects gas into the vacuum of space at a staggering speed of 164 kilometers per second (about 367,000 miles per hour). This rapid expansion causes the gas to lose internal energy and cool down significantly, similar to how air feels cold when it escapes a pressurized tire or aerosol can.In 1995, observations from the 15-meter Swedish-ESO Submillimetre Telescope in Chile confirmed that the nebula's temperature is a mere 1 Kelvin. This is colder than the Cosmic Microwave Background (CMB) radiation, which sits at 2.7 Kelvin. The CMB is the thermal remains of the Big Bang that permeates all of space, meaning the Boomerang Nebula is the only known object that absorbs this background radiation rather than emitting more heat than it.Raghvendra Sahai and Nyman published these findings in the Astrophysical Journal, establishing the nebula as the coldest natural environment ever recorded. While scientists on Earth have created colder temperatures in laboratories using lasers and magnetic traps, no other natural phenomenon has been found to match this level of frigidity. The nebula continues to expand and cool, providing a unique laboratory for studying the physics of dying stars.