In most calendar systems, two astronomical objects 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 a warmer climate 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 to the lower left of the Moon as night falls this evening, and even closer to the Moon at first light tomorrow.

Regulus was one of the most important stars of the ancient world. In ancient Persia it was one of the four “guardians of heaven,” 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 this month — villagers begin preparing the fields for crops. And they begin planting mountain corn when the waxing Moon passes by Regulus in March — an important reminder that’s as easy as watching the stars.

And watch Regulus as it pops into view near the Moon in early evening, and stays close throughout the night. It’ll stand just above the Moon as they set during the dawn twilight.

Script by Damond Benningfield, Copyright 2015