On February 28, 2018 – as darkness falls around the world – the star Regulus, aka 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 on this date.
The first of a monthly series of 19 lunar occultations of Regulus started on December 18, 2016, and will conclude on April 24, 2018. That means Regulus will be briefly hidden behind the moon – as seen from parts of the world – on this date. The February 28 (March 1), 2018, occultation of Regulus is visible from Greenland, northern Canada and Alaska. Click here for more information on this lunar occultation of Regulus.
Regulus is considered to be the most important of the four Royal Stars of ancient Persia.
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 course of time, they still mark the four quadrants of the heavens.
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.
Bottom line: On the night of February 28, 2018, use the waxing gibbous moon to find the Royal Star Regulus!
Bruce McClure has served as lead writer for EarthSky's popular Tonight pages since 2004. He's a sundial aficionado, whose love for the heavens has taken him to Lake Titicaca in Bolivia and sailing in the North Atlantic, where he earned his celestial navigation certificate through the School of Ocean Sailing and Navigation. He also writes and hosts public astronomy programs and planetarium programs in and around his home in upstate New York.