What does it mean if Betelgeuse Goes Supernova?

Orion's brilliant, crimson star Betelgeuse has exhibited some peculiar behavior lately. It became fainter than we had ever seen it in late 2019 and early 2020, at least according to records going back more than a century. It briefly dimmed until it was nearly as bright as Bellatrix, the third brightest star in Orion. This occurrence came to be known as the "great dimming."

Betelgeuse has since recovered its brightness, though. It was the brightest star in Orion for a few days this year, the brightest we have ever seen it. Both incidents raised the possibility that an explosion would eventually bring it to an end. But is there any proof to back up this claim? And what impact would such an explosion have on those of us on Earth?

Generally speaking, stars are incredibly steady. Year after year, they continue to sparkle with the same intensity. There are, however, certain exceptions, and some stars, known as variable stars, undergo brightness changes. The most well-known variable star is Mira, or the "star of wonder," which was found by the German priest David Fabricius in 1596. It pulses and periodically expands and contracts.

Another well-known example is Algol, which periodically has a companion star eclipse it. The brightness of about 30 of these variable stars can be seen with the unaided eye, but it takes some effort to do so.

The brightest of the variable stars is Betelgeuse, which is the seventh-brightest star in the sky (excluding the Sun). Betelgeuse fluctuates in brightness, occasionally being noticeably fainter than Rigel (the fourth brightest blue star in the constellation). Pulsations that are comparable to those of Mira, while smaller and less frequent, are what produce the variance.

However, a star occasionally experiences brief bursts of intense brightness. The supernovas, generated when a complete star ends its existence in a massive explosion, are the brightest and rarest of those.

Supernovas have only happened a few times in the past 1,000 years, but they can be brilliant enough to be seen during the day. Astronomers dream of seeing a nearby, brilliant supernova, but few of us will ever get the chance. In hope do we live.

Betelgeuse is a variable star, but the 2021 great dimming was severe. In fact, it had darkened by nearly 60% in just a few months. In the end, it was determined that a cloud was to blame. Stars like Betelgeuse are constantly ejecting dust and gas. Half of the star was hidden by a clump of gas in the wind that was as big as the star itself. In actuality, the star's southern half was absent from photos of it. Some stars, like Betelgeuse, seem to have weather.

Despite this, it is now 50% brighter than usual; the cause of the unexpected brightening is yet unknown. However, it doesn't appear that a supernova is about to explode. The core of these types of stars ignites a supernova explosion. On the other hand, brightness changes are a surface phenomenon.

The same dust cloud that produced the dimming and is now bouncing light from the star towards us may perhaps be to blame for the extraordinary brightening.

Although astronomers are enthusiastic, we can't be certain. Betelgeuse is a star with a mass that is between 15 and 20 times that of the Sun, and stars with this mass are thought to end their lives in a supernova explosion. Because Betelgeuse is a red supergiant, its crimson tint indicates that it is already nearing the end of its existence.

But it might still be a million years before that happens. According to astronomers, a star like Betelgeuse can survive for more than 10 million years, but to the average person, it is a very long time.

Despite this, new models have been developed, with some predicting that a supernova will occur in a few thousand years and others estimating that it will happen 1.5 million years from now.

Around Betelgeuse, there are numerous unsolved mysteries. Its exact mass is unknown, and even how far away it is is debatable. The star may have recently merged with a smaller partner, which would account for its faster rotation than would be predicted given the typical rotation of big stars.

In some old texts, the star is compared to yellowish Saturn rather than crimson Mars. Has the star's color changed? That would indicate rapid evolution, which would suggest that a supernova might occur sooner rather than later.

What would Betelgeuse's supernova look like if it happened? Around 500 light years separate us from the star. We would initially see a neutrino rain after an explosion, which would be safe for us to observe. The star would quickly become brighter after that.

It would shine with almost the same brightness as the Full Moon after a week or two. Then, over the following months, Betelgeuse would diminish, but it would still be visible during the day for six to twelve months. For another year or two, you should be able to see it clearly at night with the unaided eye. The crimson glimmer in Orion would then vanish forever, and we would never see it again.

Are we in any danger? Cosmic rays, which are produced by supernovae, are high-energy particles that can penetrate the Earth's magnetic field. However, aside from the closest supernovas, the amounts would be negligible in comparison to other radiation humans are exposed to.

Radioactive iron would also be produced during a supernova explosion. In actuality, this substance, which has been discovered on the Moon and in the seafloor of the Earth, is thought to have created in a supernova explosion between two and three million years ago. That supernova was about 300 light years away from us, so it was closer than Betelgeuse but still sufficiently remote to not pose a serious threat to life as we know it.

A supernova that is less than 30 light years away could pose serious issues because the cosmic rays it emits could harm Earth's ozone layer and increase UV radiation levels. This level is thought to be capable of producing an extinction catastrophe since it may cut ozone levels in half over a period of hundreds to thousands of years. However, such a near supernova would be extremely uncommon and might only occur once every billion years.

In the end, Betelgeuse may continue to exist for some time. It's an intriguing and enigmatic star, so that's nice. There is still much for us to learn from it.