<p><strong>No.</strong></p>

<p>Lunar eclipses are caused when the Moon is in opposition to the Sun. Normally this produces a full moon, but if the Moon is in exact opposition (considering incline of the Moon's orbital plane), all direct sunlight will be blocked from the Moon:</p>

<p><a href="https://i.sstatic.net/5CKA0.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/5CKA0.png" alt="enter image description here"></a></p>

<p>So if all the sunlight is blocked, how can we see the Moon? Well, the main reason is that sunlight is often dispersed in the atmosphere, and so it can reach the Moon. In addition, there's  <a href="https://en.wikipedia.org/wiki/Airglow" rel="nofollow noreferrer">airglow</a>, which is when sunlight hits Earth's upper atmosphere and causes multiple chemical reactions, scattering light throughout the night sky.</p>

<p>Thus, all this light from Earth, called <a href="https://en.wikipedia.org/wiki/Planetshine#Earthshine" rel="nofollow noreferrer">earthshine</a>, reflects off the Moon and illuminates it. In addition, Earth removes and blocks parts of the sunlight's spectrum, leaving only the longer wavelengths. This causes the Moon to appear red. Lastly, because the Earth blocks off all the direct sunlight from the Sun (only diffracted sunlight and airglow reach the Moon), we can actually see Earth's shadow on the Moon. </p>

CC BY-SA 3.0
2016-09-21T18:42:19.927Z
So even at a Danjon Scale value of 0 the Moon will not be completely blacked out like the Sun is during a Solar Eclipse?
Jake Clawson
CC BY-SA 3.0
2016-09-21T19:45:57.620Z
I'm surprised by your statement that airglow is a major source of the light we see from the Moon during a total lunar eclipse. I've always assumed that most or all of the reddish light is sunlight refracted through Earth's atmosphere. (An observer standing on the Moon would see every sunrise and sunset simultaneously.) And the cited Wikipedia article says that airglow is generally bluish. Do you have a source saying that airglow is significant in lunar eclipses?
Keith Thompson
CC BY-SA 3.0
2016-09-21T20:36:09.813Z
@JakeClawson That's right. It'll be nearly invisible, but not quite invisible.
Sir Cumference
CC BY-SA 3.0
2016-09-21T20:38:09.170Z
@KeithThompson The lunar eclipse is visible due to earthshine (aka earthlight). If you read on [Wikipedia](https://en.wikipedia.org/wiki/Earthlight_(astronomy)), you can see that it's caused "by light reflected from the Earth and from the Earth's airglow."
Sir Cumference
CC BY-SA 3.0
2016-09-21T20:42:13.783Z
Airglow and reflected/refracted sunlight are two different things. Airglow is specifically light emitted by the atmosphere itself; it is not reflected or refracted sunlight. Your answer says that the visibility of the Moon during a total lunar eclipse is "mostly thanks to airglow". I don't believe that's correct. I think that the visibility is almost entirely due to sunlight refracted through Earth's atmosphere, with airglow making a much smaller contribution.
Keith Thompson
CC BY-SA 3.0
2016-09-21T20:46:30.683Z
@KeithThompson I know what airglow is; it's a chemical reaction caused by sunlight in the upper atmosphere. Airglow is, of course, dependent on how much sunlight hits Earth's atmosphere. Usually, as the amount of reflected light increases, so will the airglow. It's a direct factor in earthshine. If you have a clear source indicating that airglow doesn't play as big a role, feel free to share it.
Sir Cumference
CC BY-SA 3.0
2016-09-21T20:52:14.277Z
Airglow is bluish. Sunrises and sunsets are reddish. The Moon, during a total lunar eclipse, is distinctly reddish. Airglow is very dim; it wasn't even identified until 1868. Indirect sunlight shortly after sunset or shortly before sunrise is much brighter, and that's what shines on the Moon during an eclipse. This is all off the top of my head; I have no firm numbers. Do you have evidence that airglow is significant during total lunar eclipses?
Keith Thompson
CC BY-SA 3.0
2016-09-21T20:54:03.987Z
@KeithThompson All right, I defer to your argument. I'll make the edit.
Sir Cumference
CC BY-SA 3.0
2016-09-21T18:13:23.763Z
2016-09-21T20:56:43.187Z
2016-09-21T20:56:43.187Z
Sir Cumference
<p>Can a lunar eclipse completely 'turn off' the mooon, i.e. like a New Moon? Or is it always just a 'shading' of the moon (sometimes red in color)?</p>

<lunar-eclipse>
Lunar Eclipse - Total darkness?
Jake Clawson
# Lunar Eclipse - Total darkness?

(Asked by: username_0 on 2016-09-21)

Can a lunar eclipse completely 'turn off' the mooon, i.e. like a New Moon? Or is it always just a 'shading' of the moon (sometimes red in color)?

**Tags:** lunar-eclipse


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## 1 answers

### Answer by username_1 on 2016-09-21. Score: 1 | Accepted answer

**No.**

Lunar eclipses are caused when the Moon is in opposition to the Sun. Normally this produces a full moon, but if the Moon is in exact opposition (considering incline of the Moon's orbital plane), all direct sunlight will be blocked from the Moon:

[![enter image description here](https://i.sstatic.net/5CKA0.png)](https://i.sstatic.net/5CKA0.png)

So if all the sunlight is blocked, how can we see the Moon? Well, the main reason is that sunlight is often dispersed in the atmosphere, and so it can reach the Moon. In addition, there's [airglow](https://en.wikipedia.org/wiki/Airglow), which is when sunlight hits Earth's upper atmosphere and causes multiple chemical reactions, scattering light throughout the night sky.

Thus, all this light from Earth, called [earthshine](https://en.wikipedia.org/wiki/Planetshine#Earthshine), reflects off the Moon and illuminates it. In addition, Earth removes and blocks parts of the sunlight's spectrum, leaving only the longer wavelengths. This causes the Moon to appear red. Lastly, because the Earth blocks off all the direct sunlight from the Sun (only diffracted sunlight and airglow reach the Moon), we can actually see Earth's shadow on the Moon.

> **Comments:**
> **username_0**: So even at a Danjon Scale value of 0 the Moon will not be completely blacked out like the Sun is during a Solar Eclipse?  
> **username_2**: I'm surprised by your statement that airglow is a major source of the light we see from the Moon during a total lunar eclipse. I've always assumed that most or all of the reddish light is sunlight refracted through Earth's atmosphere. (An observer standing on the Moon would see every sunrise and sunset simultaneously.) And the cited Wikipedia article says that airglow is generally bluish. Do you have a source saying that airglow is significant in lunar eclipses?  
> **username_1**: @JakeClawson That's right. It'll be nearly invisible, but not quite invisible.  
> **username_1**: @KeithThompson The lunar eclipse is visible due to earthshine (aka earthlight). If you read on [Wikipedia](https://en.wikipedia.org/wiki/Earthlight_(astronomy)), you can see that it's caused "by light reflected from the Earth and from the Earth's airglow."  
> **username_2**: Airglow and reflected/refracted sunlight are two different things. Airglow is specifically light emitted by the atmosphere itself; it is not reflected or refracted sunlight. Your answer says that the visibility of the Moon during a total lunar eclipse is "mostly thanks to airglow". I don't believe that's correct. I think that the visibility is almost entirely due to sunlight refracted through Earth's atmosphere, with airglow making a much smaller contribution.  
> **username_1**: @KeithThompson I know what airglow is; it's a chemical reaction caused by sunlight in the upper atmosphere. Airglow is, of course, dependent on how much sunlight hits Earth's atmosphere. Usually, as the amount of reflected light increases, so will the airglow. It's a direct factor in earthshine. If you have a clear source indicating that airglow doesn't play as big a role, feel free to share it.  
> **username_2**: Airglow is bluish. Sunrises and sunsets are reddish. The Moon, during a total lunar eclipse, is distinctly reddish. Airglow is very dim; it wasn't even identified until 1868. Indirect sunlight shortly after sunset or shortly before sunrise is much brighter, and that's what shines on the Moon during an eclipse. This is all off the top of my head; I have no firm numbers. Do you have evidence that airglow is significant during total lunar eclipses?  
> **username_1**: @KeithThompson All right, I defer to your argument. I'll make the edit.  

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