Many ancient cultures thought of the stars as fixed and unchanging. Any change they did see was a bad sign. A star in Perseus that gradually fades and brightens, for example, was called the demon star.

Goodness only knows what they would have called Betelgeuse, the orange shoulder of Orion. It’s normally the 10th-brightest star in the night sky. In late 2019 and early 2020, though, it dropped out of the top 20. It faded to only about a third of its normal brightness, although it eventually recovered.

Betelgeuse is a supergiant. It’s much bigger, heavier, and brighter than the Sun. The exact numbers are uncertain, mainly because its distance is uncertain. A recent study put it at about 550 light-years — closer than earlier studies.

Betelgeuse is only about nine million years old, yet it’s near the end of its life. It “burns” through its nuclear fuel at a furious rate. When it’s through, it’ll explode as a supernova — a blast that’ll be visible in the daytime for weeks.

Astronomers expect that to happen in the next hundred thousand years or so. So when Betelgeuse faded, there was some speculation that it was a prelude to the final blast. Most studies, though, say the star faded because it blew a giant blob of gas into space. The blob cooled and darkened, making Betelgeuse fade away.

Still, we know it’s only a matter of time until the star’s brilliant end — an event that would have been really scary for long-ago skywatchers.

Script by Damond Benningfield

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