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Moon and Regulus

February 9, 2020

A star can be much more than meets the eye. An example is Regulus, the “heart” of Leo, the lion. Although it looks like a single star, it’s actually a system of at least four stars. But only one of them is bright enough to see without a telescope.

The bright star is quite impressive. Known as Regulus A, it’s bigger and heavier than the Sun, and much brighter. And it’s spinning like crazy — so fast that it’s barely holding itself together.

The star has a close companion — the likely corpse of a once-impressive star. Today, it’s so small and faint that it’s impossible to see through the glare of Regulus A, even with the biggest telescopes. So it wasn’t discovered until a little more than a decade ago.

The other members of the system are Regulus B and C. Regulus B is a little smaller and fainter than the Sun, while C is a cool, dim cosmic ember known as a red dwarf. They form a loosely bound pair that’s hundreds of billions of miles from the other two stars.

At that range, it takes the two pairs of stars more than a hundred thousand years to orbit each other. So it’s hard to be absolutely certain that B and C are really bound to the other two. But all four stars appear to move through space in sync — making the Regulus system more than meets the eye.

You should have no trouble eyeing Regulus tonight. It’s close to the right of the just-past-full Moon in early evening, and keeps tabs on the Moon throughout the night.

Script by Damond Benningfield

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