Elizabeth Weise

USATODAY

SAN FRANCISCO — This weekend may prove eye-popping for sky watchers.

Sunday night brings a supermoon, when the full moon coincides with the moon's closest approach to the Earth during its elliptical orbit around us.

The full moon will appear 14% bigger and 30% brighter than when it is at its farthest, says Ben Burress, an astronomer with the Chabot Space and Science Center in Oakland.

The moon will be 190,000 miles from the Earth, 20% closer than its farthest point, when it is 240,000 miles away.

"Supermoon" isn't an astronomical term. It became popular only in the past few years, according to the website EarthSky.com. The term was coined by an astrologer, Richard Nolle, over 30 years ago.

Astronomers call them perigee full moons, as perigee means "near Earth." Still, the term doesn't quite fit with the glory of a rising supermoon, so even science sites have started using it.

The light of the supermoon will have the unfortunate effect of making the annual return of the Perseid meteor shower less visible, though.

The prolific Perseids peak between Aug. 10 and Aug. 13. When there's no moonlight to interfere, they can fill the night sky with as many as 80 shooting stars an hour.

This year's show will be muted by the moon as it wanes, but some of the Perseids' brighter meteors should be visible.

To find them, look in the constellation Perseus, which is just to the left of the Pleiades, the Seven Sisters constellation, in the northeastern portion of the sky.

Another option is to look just after sunset, when the moon is still low, says Alan MacRobert, senior editor at Sky & Telescope magazine.