Enjoying EarthSky? Subscribe.

271,628 subscribers and counting ...

Where’s the moon? Waxing gibbous

It’s waxing toward full moon and a partial lunar eclipse on August 7-8. This week’s waxing moon means moonlight for the Perseid meteor shower on the peak mornings of August 12 and 13.

Waxing gibbous moon via Clarise Samuels in Montreal. She used multiple exposures to superimpose the moon on a close-up of small light bulbs and she wrote: “It would be nice if we had a lot of moons.” Wannabe meteor-watchers will disagree!

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.

This week’s waxing gibbous moon rises during the hours between noon and sunset. It sets in the wee hours after midnight. It falls between a first quarter moon and a full moon.

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.

A gibbous moon can also be a waning gibbous, in the week between full moon and last quarter moon. Want to know more? Check out our post offering 4 keys to understanding moon phases.

Point of interest on a waxing gibbous moon: Sinus Iridum (Bay of Rainbows) surrounded by the Jura Mountains. Photo by Lunar 101-Moon Book in Toronto, Canada.

As the moon orbits Earth, it changes phase in an orderly way. Follow these links to understand the various phases of the moon.

Four keys to understanding moon phases

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