Moon and El Nath

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Moon and El Nath

The Moon hangs precariously above a star with a nasty-sounding name tonight: El Nath. The name comes from an Arabic phrase that means “butting” or “goring.” It indicates the star’s position in its constellation — at the tip of one of the horns of Taurus, the bull.

The star itself is impressive. It’s about five times the size and mass of the Sun. And it’s much brighter. If you consider just its visible light, El Nath is about 300 times brighter than the Sun. So it looks bright even though it’s more than 130 light-years away — the 25th-brightest star in all the night sky.

But the eye alone doesn’t reveal a star’s complete story. El Nath is many thousands of degrees hotter than the Sun. Hot stars shine blue-white. And they also produce a lot of ultraviolet light — wavelengths that are far too short for the eye to see. When you factor in the ultraviolet and all other forms of light, El Nath is about 700 times the Sun’s brightness.

El Nath appears to be about a hundred million years old — only a few percent the age of the Sun. Yet it’s already nearing the end of its life. It’s puffing up as a result of changes in the nuclear reactions taking place in its core. Before long — on the astronomical time scale — it’ll swell to hundreds of times the Sun’s diameter. So El Nath will shine much brighter than it is now — making the tip of the bull’s horn even more impressive.

Script by Damond Benningfield

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