<p>The Moon receives most of its light from the Sun, either directly through sunlight or indirectly through Earthshine. However, there are many other dimmer sources of illumination. </p>

<ul>
<li><p><strong>Starlight.</strong> This is probably the most important one. Under exceptional conditions, it <a href="https://apod.nasa.gov/apod/ap100823.html" rel="noreferrer">creates shadows</a> here on Earth.</p></li>
<li><p><strong>Artificial light.</strong> Mostly city lights and gas flares.</p></li>
<li><p><strong>Meteorological activity.</strong> Lightning storms on Earth and other planets are visible from space, and here on Earth, they can trigger other sources of light such as firestorms.</p></li>
<li><p><strong>Bioluminescence.</strong> Light-emitting microorganisms are bright enough and numerous enough to be <a href="http://www.pnas.org/content/102/40/14181" rel="noreferrer">seen from space</a>.</p></li>
<li><p><strong>Transient bright lights.</strong> Events such as supernovas and asteroid impacts are rare, but when they happen, they are a significant source of illumination. Over long timescales, for example a billion years, this may be the biggest contributor of non-solar light.</p></li>
</ul>

<p>How much do these light sources illuminate the Moon? If there was no Sun, could we still see the Moon with these lights? And of the three Earth-based sources (artificial light, meteorological activity, bioluminescence), which one illuminates the best?</p>

CC BY-SA 4.0
2018-05-18T06:36:55.847Z
About the bioluminescence, there's a distinction to be made between something being "detected" and something being "seen". Certainly, astronauts aboard the ISS would be unable to detect any bioluminescence. The experiment you linked used photomultiplier tubes and had to digitally enhance the signal.
Phiteros
CC BY-SA 4.0
2018-05-18T10:25:35.460Z
If there was no sun there would probably be no life on Earth.
Dr Chuck
CC BY-SA 4.0
2018-05-18T21:05:46.853Z
[Relevant xkcd](https://what-if.xkcd.com/13/). I'm betting the answer you're looking for can be derived from this calculation, and the answer would be "a negligible amount." However, I'm not enough of an expert to do that calculation.
Cody
<the-moon><light><observational-astronomy><weather>
How much do starlight and artificial light illuminate the Moon?
StarlightDown
# How much do starlight and artificial light illuminate the Moon?

(Asked by: username_0 on 2018-05-17)

The Moon receives most of its light from the Sun, either directly through sunlight or indirectly through Earthshine. However, there are many other dimmer sources of illumination.

* **Starlight.** This is probably the most important one. Under exceptional conditions, it [creates shadows](https://apod.nasa.gov/apod/ap100823.html) here on Earth.
* **Artificial light.** Mostly city lights and gas flares.
* **Meteorological activity.** Lightning storms on Earth and other planets are visible from space, and here on Earth, they can trigger other sources of light such as firestorms.
* **Bioluminescence.** Light-emitting microorganisms are bright enough and numerous enough to be [seen from space](http://www.pnas.org/content/102/40/14181).
* **Transient bright lights.** Events such as supernovas and asteroid impacts are rare, but when they happen, they are a significant source of illumination. Over long timescales, for example a billion years, this may be the biggest contributor of non-solar light.

How much do these light sources illuminate the Moon? If there was no Sun, could we still see the Moon with these lights? And of the three Earth-based sources (artificial light, meteorological activity, bioluminescence), which one illuminates the best?

**Tags:** the-moon, light, observational-astronomy, weather

> **Comments:**
> **username_1**: About the bioluminescence, there's a distinction to be made between something being "detected" and something being "seen". Certainly, astronauts aboard the ISS would be unable to detect any bioluminescence. The experiment you linked used photomultiplier tubes and had to digitally enhance the signal.  
> **username_2**: If there was no sun there would probably be no life on Earth.  
> **username_3**: [Relevant xkcd](https://what-if.xkcd.com/13/). I'm betting the answer you're looking for can be derived from this calculation, and the answer would be "a negligible amount." However, I'm not enough of an expert to do that calculation.  

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## 0 answers

