When Sir Patrick Moore, the late president of the British Astronomical Association, went outside on a cold, clear night, he would look up at the sky and take his usual vigil.
“I look at Orion before anything else,” he writes about the constellation“to make sure Betelgeuse is still there in his familiar form!”
Betelgeuse, located on the hunter’s shoulder, takes its name from an Arabic term meaning “giant’s shoulder,” and the unpredictable supergiant star has always inspired vigilance. While stars often exude stability over millions of years, this one is known for its bouts of dimming, brightening, flaring and otherwise puzzling astronomers.
And since Moore died in 2012, things have only gotten worse.
What is Betelgeuse?
Betelgeuse is a massive star, about 700 times the size of the sun. In 2019, a powerful jet rose from its interior, NASA hypothesizes, and blasted off part of the star’s outer layer.
The ejected material, which weighed several times that of our moon, cooled in space, where it blocked light from reaching the ground and dramatically dimmed Moore’s star in what became known as The Great Eclipse. Backyard observers around the world noticed the change, which lasted for several months.
After its dramatic vomit, Betelgeuse fell into a period of turbulence that is expected to last at least another year or two. Its internal convection cells, which normally govern its characteristic dimming and dimming, now slosh around like an unbalanced washing machine, NASA says. At the top level, the scarred surface bounces around “like a plate of gelatin dessert.”
The Sun has often ejected small amounts of material in a similar fashion called a coronal mass ejection (CME), but the Betelgeuse belch was 400 billion times larger than the average CME.
Read more: How old is the sun?
When will Betelgeuse explode?
In recent years, the star has traded its steady 400-day glow-and-dull cycle for something much shorter and more spasmodic. The lightening in recent weeks is even raised the alarm that the aging star, located about 650 light-years from Earth, may explode in a supernova, one of the most violent events in the universe. But scientists said such an event would likely take another 10,000 to 100,000 years.
When researchers at the Kavli Institute for the Physics and Mathematics of the Universe, Japan, analyze Betelgeuse in 2020they concluded that the star was still in the early stages of burning helium.
“Betelgeuse is not at all close to exploding,” a press release said, and what’s more, the star “is too far from Earth for a possible explosion to have a significant impact here.”
Read more: What happens when a star dies?
Will Betelgeuse turn into a black hole?
As a massive star, Betelgeuse is expected to undergo a dramatic end-of-life catastrophe that will produce either a neutron star or a black hole and possibly a show for any surviving observers on earth.
Before the crash, Betelgeuse must burn several different types of nuclear fuel. Starting with hydrogen already fused into helium, the fuel for its current stage will make carbon. These reactions release large amounts of energy and send many, many photons into the universe, including those that reached Moore’s eyes.
Betelgeuse’s next stages will happen faster as its temperatures rise, sending the star down a slippery slope. Nuclear fusion will create oxygen, neon, silicon and finally iron, which accumulates in a huge core.
Read more: This is what a black hole sounds like
Betelgeuse star explosion
The reactions continue, but they sap energy from the star and upset the balance between expansion and gravitational contraction, causing the star to collapse in on itself and trigger a stunning explosion, a supernova.
When the core crashes, it sends a shock wave which compresses the surrounding stellar materials, making rare elements such as silver, tin, gold, uranium, mercury and zinc.
The entire process will release 100 times more energy than our Sun has in its 10 billion lifetime and leave behind an exotic remnant, a black hole or neutron star.
Read more: How big are neutron stars?