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Moon and Regulus on March 10

Tonight – March 10, 2017 – as darkness falls around the world, the star Regulus, sometimes called the Heart of the Lion in the constellation Leo, appears near the moon. Although Regulus rates as a 1st-magnitude star (that is, one of the brightest stars in the sky), you might have difficulty spotting it in the glare of the waxing gibbous moon tonight.

The first of a monthly series of 19 lunar occultations of Regulus started on December 18, 2016, and will conclude on April 24, 2018. However, you have to be at the right spot on Earth to witness any one of these occultations. This one will be visible from Cape Town, South Africa on March 11 from 12:44 a.m. to 1:34 a.m. local time.

March 11, 2017 occultation of Regulus. Map via IOTA. Not many places on land are in a good position to watch this occultation, except for the southern tip of South Africa.

Regulus is considered to be the most important of the four Royal Stars of ancient Persia.

These Royal Stars mark the four quadrants of the heavens. They are Regulus, Antares, Fomalhaut, and Aldebaran.

Four to five thousand years ago, the Royal Stars defined the approximate positions of equinoxes and solstices in the sky. Regulus reigned as the summer solstice star, Antares as the autumn equinox star, Fomalhaut as the winter solstice star, and Aldebaran as the spring equinox star. Regulus is often portrayed as the most significant Royal Star, possibly because it symbolized the height and glory of the summer solstice sun. Although the Royal Stars as seasonal signposts change over the long coarse of time, they still mark the four quadrants of the heavens.

An imaginary line drawn between the pointer stars in the Big Dipper – the two outer stars in the Dipper’s bowl – points in one direction toward Polaris, the North Star, and in the opposite direction toward Leo.

Regulus coincided with the summer solstice point some 4,300 years ago. In our time, the sun has its annual conjunction with Regulus on or near August 22, or about two months after the summer solstice – or alternatively, one month before the autumn equinox. Regulus will mark the autumn equinox point some 2,100 years into the future.

If you miss the moon close to star Regulus on March 10, look again on March 11. The star at the Tail of Leo – the bottom of that little tail-end triangle – is called Denebola.

Bottom line: On the night of March 10, 2017, use the waxing gibbous moon to find the Royal Star Regulus! The very bright planet Jupiter shines to the east of the moon and Regulus on this night. On March 11, the moon will occult or cover Regulus.

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Bruce McClure

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