Those who want to watch the annual Perseid meteor shower are now shaking their fists at this week’s waxing gibbous moon. It’s more than half-lighted, less than full, but steadily waxing toward full moon on the night of August 7-8, 2017. Afterwards, the moon will be waning, but still bright in the sky after midnight during the Perseids’ peak. As if in consolation (although not for us in the Americas), the upcoming full moon will feature a partial lunar eclipse, visible from Earth’s Eastern Hemisphere on the night of August 7-8. And of course this cycle of the moon is moving us inexorably toward the much-anticipated total eclipse of the sun on August 21, which will cut a narrow (and likely crowded!) swath across the U.S.
Any moon that appears more than half lighted but less than full is called a gibbous moon. The word gibbous comes from a root word that means hump-backed.
People often see a waxing gibbous moon in the afternoon, shortly after moonrise, while it’s ascending in the east as the sun is descending in the west. It’s easy to see a waxing gibbous moon in the daytime because, at this phase of the moon, a respectably large fraction of the moon’s dayside is now facing our way.
As the moon orbits Earth, it changes phase in an orderly way. Follow these links to understand the various phases of the moon.
Where’s the moon? Waxing crescent
Where’s the moon? First quarter
Where’s the moon? Waxing gibbous
What’s special about a full moon?
Where’s the moon? Waning gibbous
Where’s the moon? Last quarter
Where’s the moon? Waning crescent
Where’s the moon? New phase
Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. "Being an EarthSky editor is like hosting a big global party for cool nature-lovers," she says.