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Moon and Antares

February 23, 2022

The brightest and closest exploding star in centuries was first seen 35 years ago tonight. Supernova 1987a was bright enough to see with the unaided eye. To understand how bright that really was, consider that the supernova was in another galaxy — more than 160,000 light-years away. It’s faded from view since then, but astronomers still keep a close eye on it through telescopes on the ground and in space.

Several stars in our own galaxy, the Milky Way, are likely to explode as supernovas fairly soon. On the astronomical time scale, that means any time within the next hundred thousand years or so. And when they go, they’ll be bright enough to see in the daytime for weeks or months.

One of the best candidates is Antares, the leading light of Scorpius. The brilliant star is quite close to the Moon at first light tomorrow.

Antares is actually a binary — two giant stars locked in a mutual orbit. The brighter star is roughly a dozen times the mass of the Sun. At that great heft, it’s destined to explode as a supernova. Its core will collapse to form a neutron star. Its outer layers will fall inward, then rebound, blasting out into space.

The star is roughly 15 million years old. That’s quite young compared to most stars. But for a star of its mass, Antares is quite late in life. So the nuclear reactions that power the star are quickly building to a climax — setting up Antares for a brilliant and powerful demise.

Script by Damond Benningfield

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