Earthshine: what it is, how to see it

How to spot earthshine, when light reflected off Earth lights up the Moon’s dark side.

Also known as the Da Vinci Glow, earthshine allows us to see features on the Moon’s dark side. Credit: Pete Lawrence

Earthshine is a phenomenon that allows us to see the dark, night side of the Moon. To understand the effect, it’s important to be able to imagine what Earth looks like from the Moon.

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Our planet is more reflective than the Moon by quite some margin. Although you might not think it, the Moon’s reflectivity is about the same as an asphalt road.

Earth Shine by Brian.M.Johnson, Kelling Heath, uk Equipment: Sky 90, Canon 50d, Tripod
Earth Shine by Brian.M.Johnson, Kelling Heath, uk Equipment: Sky 90, Canon 50d, Tripod

Earth is also approximately four times larger than the Moon. Put together it’s not hard to imagine that Earth would appear big and bright as seen from the lunar surface.

Read more about the Moon:

What about the phase of Earth? We’re all familiar with the phases of the Moon caused by the varying Moon-Earth-Sun angle as our neighbour travels around its orbit, but what would Earth look like from the Moon?

It too would go through a complete set of phases but these will be the complementary ones to what we see from Earth.

When the Moon is full in our sky, Earth will be new in the Moon’s sky. When the Moon is a thin crescent, Earth would appear with a large gibbous phase.

Arrows show the weak earthshine-lit portion of a waxing gibbous Moon. Credit: Pete Lawrence
Arrows show the weak earthshine-lit portion of a waxing gibbous Moon. Credit: Pete Lawrence

The thin crescents we see just before and after new Moon therefore represent times when Earth’s light shining onto the Moon is at its strongest.

This light illuminates the dark, night portion of the Moon’s Earth-facing side and reflects back to Earth, allowing us to see the lunar night hemisphere glowing gently.

This is what’s known as earthshine. Another, more poetic term for the effect is ‘the old Moon in the young Moon’s arms’, describing the appearance we get with the early evening crescent Moon when it reappears just after the new phase.

The Moon by Clive Hollinshead, UK. Equipment: Canon eos 1200D, 70-300mm lens, tripod.
The Moon by Clive Hollinshead, UK. Equipment: Canon eos 1200D, 70-300mm lens, tripod.

Looking at the earthshine-lit portion of the lunar disc with a scope it is just possible to see certain features. The most obvious is the bright crater Aristarchus near to the western limb.

Photography is another excellent way to reveal features within the lunar night. Deliberately over-exposing a bright lunar crescent will reveal many details from the ‘dark side’, rendering the night portion as detailed as it appears when properly lit.

It’s pretty easy to see and photograph the earthshine-lit portion of the Moon when the Moon is showing as a thin crescent, but how close to full Moon can you get and still record the effect. 

Pictures of Earthshine

Below is a selection of photos of Earthshine captured by BBC Sky at Night Magazine readers and astrophotographers. For advice on lunar imaging, read our guide on how to photograph the Moon or our beginner’s guide to astrophotography.

And don’t forget to send us your images or share them with us via Facebook, Twitter and Instagram.

Starry Earthshine by Brendan Alexander, Donegal, Ireland. Equipment: Canon 1000D, Omni XLT 150, CG5
Starry Earthshine by Brendan Alexander, Donegal, Ireland. Equipment: Canon 1000D, Omni XLT 150, CG5
Moon Glow by Brendan Alexander, Donegal, Ireland. Equipment: Canon 1000D
Moon Glow by Brendan Alexander, Donegal, Ireland. Equipment: Canon 1000D
Purple Haze by Kirk Macey, Cranleigh, Surrey, UK. Equipment: 120mm Skywatcher refracter, Canon 450D, Fringe Killer Filter.
Purple Haze by Kirk Macey, Cranleigh, Surrey, UK. Equipment: 120mm Skywatcher refracter, Canon 450D, Fringe Killer Filter.
Earthshine 3rd September 2013 by Aprill Harper, Blunham, Bedfordshire, UK. Equipment: Samsung NX1000, SkyWatcher 8
Earthshine 3rd September 2013 by Aprill Harper, Blunham, Bedfordshire, UK. Equipment: Samsung NX1000, SkyWatcher 8″ Dobsonian
Earthshine by Tom Howard, Crawley, Sussex, UK. Equipment: Nikon D7000, Meade 5000 127mm refractor, EQ6.
Earthshine by Tom Howard, Crawley, Sussex, UK. Equipment: Nikon D7000, Meade 5000 127mm refractor, EQ6.
Earthlight by Martin Rogers, Edgcott, Buckinghamshire, UK. Equipment: Celestron C8N, Pentax K5 at prime focus, motorised CG5 mount
Earthlight by Martin Rogers, Edgcott, Buckinghamshire, UK. Equipment: Celestron C8N, Pentax K5 at prime focus, motorised CG5 mount
Setting Moon with Earthshine by Steve Brown, Stokesley, N. Yorkshire, UK. Equipment: Canon 600D, 250mm lens, tripod.
Setting Moon with Earthshine by Steve Brown, Stokesley, N. Yorkshire, UK. Equipment: Canon 600D, 250mm lens, tripod.
Crescent Moon and Earthshine by Ron G, Stafford, UK. Equipment: Canon 1200D, tripod, Tamron 70-300mm lens
Crescent Moon and Earthshine by Ron G, Stafford, UK. Equipment: Canon 1200D, tripod, Tamron 70-300mm lens
Earthshine by Sarah & Simon Fisher, Bromsgrove, Worcestershire, UK. Equipment: Canon 600D, 300mm lens
Earthshine by Sarah & Simon Fisher, Bromsgrove, Worcestershire, UK. Equipment: Canon 600D, 300mm lens
Lunar Earthshine by Honor Wheeler, Wilmington, Kent, UK. Equipment: Canon EOS 1100D, Canon EF-S 55-250mm lens.
Lunar Earthshine by Honor Wheeler, Wilmington, Kent, UK. Equipment: Canon EOS 1100D, Canon EF-S 55-250mm lens.
Earthshine Moon with Skywatcher 150/750 by Houssem Ksontini, Tunis, Tunisia. Equipment: Skywatcher 150/750, Nikon D5300
Earthshine Moon with Skywatcher 150/750 by Houssem Ksontini, Tunis, Tunisia. Equipment: Skywatcher 150/750, Nikon D5300
Crescent Moon by Sarah & Simon Fisher, Bromsgrove, Worcestershire, UK. Equipment: Canon 600D, 300mm lens
Crescent Moon by Sarah & Simon Fisher, Bromsgrove, Worcestershire, UK. Equipment: Canon 600D, 300mm lens
Waning Crescent Moon 11% lighting, with focus on area not lit by Fernando Oliveira De Menezes, Sao Paulo, Brazil. Equipment: Esprit 150 ED, ASI 1600mm cooled
Waning Crescent Moon 11% lighting, with focus on area not lit by Fernando Oliveira De Menezes, Sao Paulo, Brazil. Equipment: Esprit 150 ED, ASI 1600mm cooled
St. Raphael and the Moon by Paco Bellido, Cordoba, Spain. Equipment: Canon EOS 550D, Sky Watcher ED80 refractor.
St. Raphael and the Moon by Paco Bellido, Cordoba, Spain. Equipment: Canon EOS 550D, Sky Watcher ED80 refractor.
The High Dynamic Moon by Luke Oliver, Grays, Essex, UK. Equipment: Skywatcher 200P, Canon 1000D.
The High Dynamic Moon by Luke Oliver, Grays, Essex, UK. Equipment: Skywatcher 200P, Canon 1000D.
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This article originally appeared in the March 2020 issue of BBC Sky at Night Magazine.