Betelgeuse Will Briefly Disappear In Once-in-a-Lifetime Coincidence
Meghan Bartels reports via Scientific American: Some sky watchers this month will witness Betelgeuse, one of the brightest and best-known stars in the sky, nearly disappear. Mere seconds later -- despite astronomers' hopes that the star will meet its explosive end someday soon -- it will return, shining just as brightly as ever. Betelgeuse's brief blip of obscurity will mark a cosmic coincidence: an asteroid will block the star from view over a thin strip of Earth's surface. Scientists are hailing this celestial alignment as a once-in-a-lifetime occasion that, they hope, will permit them to glimpse Betelgeuse's ever changing surface of hot and cold patches in the best resolution to date. The opportunity comes courtesy of a sizable asteroid called Leona, which astronomers first spotted in 1891. On its own, Leona is just another space rock cluttering up the asteroid belt between Mars and Jupiter. But at 8:17 P.M. ET on December 11 Leona will slip directly between Earth and Betelgeuse, a red supergiant star that, unlike the asteroid, has been recognized by countless generations of humans around the world. [...] To understand how special the event is, consider the total solar eclipse that will occur in April 2024. During the climax of the eclipse, viewers across a narrow strip of Earth's surface will see the moon pass directly in front of the sun. Because the two bodies appear as the same size in our sky, the moon will entirely block the visible disk of the sun and expose the faint, wispy halo called the corona, a layer of our home star's atmosphere that scientists otherwise cannot see from Earth. Similarly, the roughly 40-mile-wide Leona appears in the sky as about the same size as the enormous but very distant Betelgeuse. This will allow the asteroid to block all or most of the star's light when the two bodies perfectly align. But whereas Earth experiences a total solar eclipse every 18 months or so, occultations of bright stars such as Betelgeuse are extremely rare, occurring less than once a century [...].
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