You are here

Moon and Regulus

March 3, 2015

The almost-full Moon glides past the heart of Leo, the lion, tonight. Regulus huddles close to the lower left of the Moon at nightfall. The planet Jupiter, which far outshines Regulus, stands well above them.

Because it was the brightest star of a prominent constellation, Regulus played a major role in the astronomy and skylore of many cultures. And they gave it names to match. In fact, Regulus means “the little king.”

That name was bestowed by Nicolaus Copernicus, the 16th-century astronomer who showed that Earth orbits the Sun, not the other way around. He adapted the name from an earlier one, Rex, which means “the king.”

Less than a century after Copernicus came up with Regulus, German astronomer Johann Bayer devised another name that’s also still in common use: Alpha Leonis, indicating that it’s the brightest or most important star of Leo.

Bayer labeled more than 1500 stars with a letter of the Greek alphabet followed by the name of its constellation. “Alpha” usually was applied to a constellation’s brightest star, but not always. Sometimes, Bayer labeled the stars based on their location, not their brightness.

Regulus qualifies as the alpha star on both counts. Not only is it the lion’s leading light, but it’s also at the bottom of a pattern that outlines the lion’s head and mane. So this “royal” star is the most prominent member of a royal constellation: Leo, the king of the beasts.

Script by Damond Benningfield, Copyright 2015

Get Premium Audio

Listen to today's episode of StarDate on the web the same day it airs in high-quality streaming audio without any extra ads or announcements. Choose a $8 one-month pass, or listen every day for a year for just $30.