Saturday evening, April 25, people across parts of the eastern United States will be able to watch a rare lunar occultation as the Moon passing directly in front of Regulus, the brightest star in the constellation Leo.
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For observers in central North Carolina The show starts shortly after 8:30 p.m. Saturday night as Regulus disappears behind the Moon.
The show starts about 10 minutes earlier in the western part of the state, about 10 minutes later along the coast.
To see the occultation look to the southeast for the waxing gibbous moon. Over the next hour, the moon will move toward the south (left). Regulus will reappear 62 minutes later.
Because the Moon has no atmosphere, Regulus will not slowly dim, but will instead appear to wink out instantly. It will later reappear along the Moon's northern limb just as sharply.
Regulus is one of the brightest stars in the night sky, shining with a blue-white color from nearly 79 light years away. It has been known since ancient times. Latin for “little king,” Regulus a lies at the heart of the constellation Leo the Lion.
Why occultations happen
Regulus lies near the ecliptic, the path followed by the Sun, Moon, and planets. Moon occasionally passes directly between the Earth and stars or planets.
Approximate times for Raleigh (EDT):
- 8:32 p.m. — Regulus disappears behind the Moon
- 9:34 p.m. — Regulus reappears from the bright edge of the Moon
Viewing tips
Look to the southwestern sky after sunset. The Moon will be easy to find, shining brightly, with Regulus to the left. No telescope is needed, the occultation can be seen with the naked eye. Binoculars or a small telescope will provide an even better view, especially for the reappearance under darker skies.
- Be outside and ready by 8:15 p.m.
- Let your eyes adjust to the dark for several minutes
- Watch the Keep the Moon in continuous view as disappearance time approaches
- Use binoculars for the reappearance if available
- Check the weather forecast in advance
Why Astronomers Care
Occultations are more than sky shows. Precise timing of when a star disappears and reappears can help astronomers refine measurements of the Moon’s orbit and position. Occultations have also revealed previously unknown double stars.
The Moon will next block Venus from view in June and Jupiter in October,. Those events will also be visible at least in part from the United States.