Moon and Regulus 
In most calendar systems, two astronomical bodies play leading roles: the Sun and Moon. Their motions across the sky define the day, the month, and the year.
Yet some calendars have relied on other lights in the sky: the stars. The first appearance of a star in morning twilight told people that it was time to plant or reap crops, or to move to warmer climes for the coming winter. Or a star reaching its highest point in the sky at midnight told them that it was time for important rituals.
One of those markers is Regulus, the brightest star of Leo, the lion. It's a little to the lower left of the Moon as night falls this evening, and keeps company with the Moon as it sails high across the sky later on.
Regulus was one of the most important stars of the ancient world. It was one of the four "guardians of heaven" in ancient Persia, so it was a key marker in the calendar.
And today, Regulus plays a role in the calendar of the Mayan people of Central America -- the descendants of the ancient Mayan civilization.
When Regulus stands highest in the sky at midnight -- which happens in February -- men begin preparing the fields for crops. And they begin planting mountain corn when the waxing Moon passes by Regulus in March -- as it does tonight.
Watch Regulus as it pops into view near the Moon in early evening, and continuing throughout the night. It'll stand just above the Moon as they set a couple of hours before sunrise.
Script by Damond Benningfield, Copyright 2010