There are few more beautiful and unique sights in all of nature than the thin crescent moon hanging over the western horizon just after sunset. Fresh out of the Sun’s glare after its invisible New Moon phase, its slider of light signals the start of its 29.5-day journey around our planet, but look closely and you’ll be able to see the Moon’s dark side.

That subtle light on the otherwise unilluminated lunar surface is called – among other things – “Earthlight” – and is the result of the reflection of sunlight from the Earth to the Moon.

This week is a fantastic time to see her at her brightest and best.

With the New Moon on Friday, June 19, the crescent moon will be visible for the next four evenings (except June 20, when it will still be in the Sun’s glare), each time showing off this eerie light.

It is possible to see “Earth” only when the Moon is a thin crescent, for two reasons:

• Just before, during and just after the New Moon there is a full Earth, so the full glare of our planet reflects all the sunlight onto the surface of the Moon.
• Our eyes can judge the dynamic range between extreme light and dark very well when the Moon is only a crescent, but its increasing glare makes it too difficult when the Moon reaches first quarter and is, from our vantage point, 50% illuminated by the Sun.

What causes ‘Earthlight’

“Earthlight” is caused by sunlight reflecting off Earth’s oceans and ice. According to reports, it is at its brightest between April and June NASA.

Also called “Earthshine”, “Planetshine” and the “Da Vinci glow” after the man who first described it in the 15th century, this lunar sight will soon be visible after sunset.

Here’s when to see “Earthlight”:

1. After sunset on Sunday, May 21

Look in the northwest sky after sunset today and you may be able to see a very thin, 5% illuminated crescent moon very low on the horizon. This will be the most difficult viewing of “Earthlight” all week, but probably the most rewarding.

Above it you will see the very bright planet Venus and, beyond that, the much less bright Mars.

This is what it will look like:

2. After sunset on Monday, May 22

Look in the northwest sky after sunset tonight and you’ll see a crescent moon at 11% brightness just below Venus among the stars of Gemini. “Earthlight” will be impossible to miss on a clear sky.

This is what it will look like:

3. After sunset on Tuesday, May 23

Tonight, a crescent moon will be visible between Venus and Mars at 18% illumination, and the brightest star of Gemini, Pollux, very close to the Moon. Until now, “Earthlight” will be spectacular, but tomorrow it will begin to fade as it is overpowered by the waxing and brightening crescent moon.

This is what it will look like:

How to see ‘Earthlight’

Look at the Moon with your naked eyes and you will see “Earthlight” very easily if the sky is clear. However, point any binoculars—of any size you can get your hands on—at the moon’s darkened limb for a close-up shot of its craters bathed in eerie light.

I wish you clear skies and wide eyes.