Moon and Regulus

Some people shine so brightly — they’re so smart, talented, effervescent, or attractive — that people overlook their siblings. The brothers and sisters might be standouts on their own, but no one seems to notice.

That happens with stars, too. Take Regulus, the brightest star of Leo, which is quite close to the Moon tonight. It’s actually a system of four stars. But one of them — Regulus Aa — gets almost all of the attention. It’s much bigger, brighter, and heavier than the Sun. And it’s the only member of the system we can see without a telescope.

One of the siblings is so faint, and so close to the brilliant star, that it was discovered just a couple of decades ago. Astronomers have devoted a lot of attention to it since then, even though they can’t actually see it — they have to use special instruments to scoop up its details.

The other two stars — Regulus B and C — have been known for much longer. But they’re smaller and less massive than the Sun, so they’re much fainter. So astronomers have paid them scant attention — few studies have ever been published on either star, and almost none in recent decades.

We do know that B and C orbit each other once every 600 years or so. And the pair is separated from Regulus Aa by at least 5,000 times the distance from Earth to the Sun. At that range, it takes several million years for the unheralded stars to orbit their attention-grabbing sibling.
 

Script by Damond Benningfield