Enjoying EarthSky? Subscribe.

211,924 subscribers and counting ...

Where’s the moon? Waxing crescent

When you see the moon as a slim crescent in the west after sunset, it’s always waxing. Is that Earth’s shadow on the moon? No, it’s the moon’s own shadow.

You can tell that Niko Powe lives at a northerly latitude because his photo of the waxing crescent moon - captured June 6, 2016 - descends from left to right. At temperate latitudes in the Southern Hemisphere, the evening crescent moon sets from right to left. Thanks, Niko!

You can tell that Niko Powe lives at a northerly latitude because his photo of the waxing crescent moon – captured June 6, 2016 – descends from left to right. At temperate latitudes in the Southern Hemisphere, the evening crescent moon sets from right to left. Thanks, Niko!

A waxing crescent moon – sometimes called a young moon – is always seen in the west after sunset.

At this moon phase, the Earth, moon and sun are located nearly on a line in space. If they were more precisely on a line, as they are at new moon, we wouldn’t see the moon. The moon would travel across the sky during the day, lost in the sun’s glare.

Here’s more to look for in tonight’s sky

But a waxing crescent moon is far enough away from that Earth-sun line to be visible near the sun’s glare – that is, in the west after sunset. This moon phase is seen one day to several days after new moon. On these days, the moon rises one hour to several hours behind the sun and follows the sun across the sky during the day. When the sun sets, and the sky darkens, the moon pops into view in the western sky.

This young moon - June, 2016 - marked the beginning of Ramadan. Abdulmajeed Alshatti wrote:

June 2016 waxing moon marked the beginning of Ramadan for Muslims around the world. Abdulmajeed Alshatti posted this photo at EarthSky Facebook on June 7 and wrote: “Muslims fast for the whole of the lunar month … This is the crescent as it appeared in Kuwait tonight (June 7).”

Note that a crescent moon has nothing to do with Earth’s shadow on the moon. The only time Earth’s shadow can fall on the moon is at full moon, during a lunar eclipse. There is a shadow on a crescent moon, but it’s the moon’s own shadow. Night on the moon happens on the part of the moon submerged in the moon’s own shadow. Likewise, night on Earth happens on the part of Earth submerged in Earth’s own shadow.

Because the waxing crescent moon is nearly on a line with the Earth and sun, its illuminated hemisphere – or day side – is facing mostly away from us. We see only a slender fraction of the day side: a crescent moon. Each evening, because the moon is moving eastward in orbit around Earth, the moon appears farther from the sunset glare. It is moving farther from the Earth-sun line in space. Each evening, as the moon’s orbital motion carries it away from the Earth-sun line, we see more of the moon’s day side. Thus the crescent in the west after sunset appears to wax, or grow fatter each evening.

Peter Lowenstein, a frequent contributor to EarthSky, caught these images of the waxing crescent moon over Mutare, Zimbabwe on June 6, 2016. He wrote:

Peter Lowenstein, a frequent contributor to EarthSky, caught these images of the waxing crescent moon over Mutare, Zimbabwe on June 6, 2016. He wrote: “This mosaic shows what it looked like as it descended though a background of various twilight colors and earthshine began to appear.”

The pale glow on the darkened portion (night side) of a crescent moon is called earthshine. Is caused by light reflected from Earth’s day side onto the moon. After all, when you see a crescent moon in Earth’s sky, any moon people looking back at our world would see a nearly full Earth. Read more: What is earthshine?

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

Understanding Moon Phases
Waxing Crescent
First Quarter
Waxing Gibbous
Full Moon
Waning Gibbous
Last Quarter
Waning Crescent
New Moon

Deborah Byrd

MORE ARTICLES