Orion is filled with so many bright stars that some of them get ignored. An example is Tabit, the star at the middle of Orion’s shield.

The star is class F6V — a designation that tells us a lot.

Astronomers categorize the stars with the letters O, B, A, F, G, K, and M. O and B stars are the biggest, hottest, and brightest. They shine blue or white. But they’re also the least common stars — they account for only a tiny fraction of one percent of all the stars in the galaxy.

K and M stars are cool and orange. They include the most common stars in the galaxy, known as M dwarfs.

A, F, and G stars are in the middle. They shine white or yellow. And the list of G stars includes the Sun.

At F6, Tabit outranks the Sun, but not by much. It’s more than a thousand degrees hotter, so it looks whiter than the Sun. It’s a little bigger and more massive than the Sun, and about three times brighter. And the “five” at the end of its classification tells us that, like the Sun, it’s still in the prime of life.

More than 200,000 years ago, Tabit would have looked about twice as bright as it does now. It was only about 15 light-years away, versus its present distance of 26 light-years.

At nightfall, Orion’s three-star belt is high in the southeast, pointing almost straight up. If you follow that line upward, the first fairly bright star you come to is Tabit — the center of the shield of Orion.

Script by Damond Benningfield

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