Moon and Regulus

The bright star HD 87901 perches just a whisker away from the crescent Moon this evening. If that name isn’t familiar to you, try this one: 32 Leo. Still not ringing any bells? Try Regulus, the little king.

Regulus is the brightest star of Leo, the lion, so it’s known as the “heart” of the lion. But the name “Regulus” has nothing to do with the king of the beasts. Instead, it refers to human royalty — the “little king” or “prince.”

The name was adapted from an earlier name: Rex, the king. That name was bestowed in ancient times, and it indicated that the star ruled the heavens. That’s because the Sun appeared near the star at the summer solstice, one of the most important dates in many ancient calendars.

Like all bright stars, Regulus has a long list of names, titles, and other designations. As the leading light of Leo, for example, it’s known as Alpha Leonis, from a system devised four centuries ago by Johannes Bayer. Each star gets a letter of the Greek alphabet, followed by the name of the star’s constellation. A constellation’s brightest star usually gets the “alpha” designation.

“32 Leo” comes from a system that was created about a century later, by John Flamsteed, in which every star in a constellation gets a number.

Many “names” are actually catalog numbers. HD 87901, for example, comes from the Henry Draper catalog. It was compiled by Harvard Observatory in the 19th and 20th centuries — providing one more way to address the stars.

Script by Damond Benningfield