THE UNIVERSE’S COLD SPOT

Beyond the frozen poles of Earth, the universe has countless regions of unimaginable coldness. However, there’s one place that’s colder than anywhere else in the cosmos: the Boomerang Nebula. This protoplanetary nebula sits around 5,000 light years from Earth and is made of clouds of gas and cosmic dust. It was discovered in 1995, and astronomers measured its temperature at only a degree above absolute zero (-272 degrees Celsius). Its chilly disposition is thought to be the result of a star throwing itself into the heart of a larger red giant star.

Normally planetary nebulae are created when a single star dies and explodes in a supernova event. During this process, the core of the star collapses under the gravity of the universe, causing gas and other cosmic matter to rapidly expand outwards into space. When gas molecules are released from the pressure created by a star’s nuclear centre and expand rapidly, they slow down and exert less thermal energy. The faster a gas expands, the slower the individual molecules move and the colder they become. The gases emitted from the collision at the heart of the Boomerang Nebula are expanding ten times faster than the gases emitted from the supernova of a single star, at around 93 miles per second, which scientists believe is the cause of its ultracool nature. The astronomers that discovered it used a ground-based telescope in Australia, revealing a curved boomerang shape. However, Hubble images have since revealed the nebula is more like a bow tie than a boomerang.