Have you ever wondered what the coolest place in the universe looks like? Well, wonder no more! Let’s journey 5,000 light-years away to meet the Boomerang Nebula, an extraordinary heavenly body with a temperature of only 1 Kelvin (−272.15 °C; −457.87 °F), making it the coldest known natural place in the cosmos.
The Boomerang Nebula, also known as the Bow Tie Nebula and catalogued as LEDA 3074547, is a protoplanetary nebula. It’s situated in the constellation Centaurus, far, far away from our home planet, Earth. In simpler terms, it’s a star system that’s still evolving and growing, thanks to the continuous outflow of gas from its core. This nebula got its unique name, the “Boomerang Nebula,” in 1980 from astronomers Keith Taylor and Mike Scarrott. They observed it with the Anglo-Australian telescope at the Siding Spring Observatory. Because of the lack of clarity, they only saw a slight asymmetry in the nebula’s lobes, which suggested a curved shape like a boomerang. Later in 1998, the Hubble Space Telescope was able to take detailed photographs of the nebula which revealed a more symmetric hourglass shape.
The Boomerang Nebula is a fascinating structure. Its core is a star in its late-stage life, which is shedding mass and emitting starlight that illuminates the dust in the nebula. This process causes the formation and development of the nebula. The grains of dust in the nebula are millimeter-scale, which mask portions of the nebula’s center, and most of the escaping visible light is in two opposing lobes. These lobes form a distinctive hourglass shape, which we can see from Earth. The gas that’s flowing out from the nebula’s core is moving outwards at an impressive speed of about 164 km/s, and it’s expanding rapidly as it moves out into space. This gas expansion results in the nebula’s unusually low temperature.
To really understand the enormity of the Boomerang Nebula, let’s compare it to something we know. The nebula is much bigger than our solar system. If we could travel at the speed of light (which is super-fast, about 299,792 kilometers per second), it would take us 5,000 years to reach the Boomerang Nebula from Earth! Now that’s really out of this world!
In 1995, astronomers using the 15-metre Swedish-ESO Submillimetre Telescope in Chile measured the Boomerang Nebula’s temperature as one degree above absolute zero (-272.15 °C). Even the 2.7 K background glow from the Big Bang is warmer than the nebula. This makes the Boomerang Nebula the coldest place in the universe that we’ve found so far, even colder than any naturally occurring object.
As of mid-2017, astronomers believe that the star at the center of the Boomerang Nebula is a dying red giant. This means that the nebula is a star system that’s evolving toward the planetary nebula phase. No matter how you look at it, the Boomerang Nebula is a fascinating part of our universe, a chilly celestial body that’s both beautiful and mysterious.