<p>While I couldn't find any quantitative information about views from Earth or orbit down to zero phase angle (especially since views direct from Earth are limited in phase angle due to Eclipse), <a href="https://asterism.org/2019/04/12/how-bright-is-the-moon/#:%7E:text=Our%20Moon%27s%20average%20visual%20albedo,dramatically%20as%20its%20phase%20changes.&amp;text=So%20if%20the%20full%20Moon,a%20brightness%20reduction%20of%2012x." rel="nofollow noreferrer">this website</a> gives an unreferenced data point suggesting Apollo astronauts observed that a zero-phase full moon is approximately 30% (0.2 magnitudes) brighter than we can ever observe from Earth.</p>
<p><a href="https://the-moon.us/wiki/Retro-Reflection_phenomena" rel="nofollow noreferrer">This site</a> cites a value stating that the moon's brightness at zero phase angle may be as much as 14x brighter than an ideal diffuse reflecting disk, with 40% of the increase within the last 5˚ of phase angle (which cannot be observed from Earth).</p>
<p>Finally, there is <a href="https://astrogeology.usgs.gov/moon-cal/modeling/irradiance.php" rel="nofollow noreferrer">one data set</a> I have found which seems to show the opposition surge effect, but as noted, it is not what I would consider complete, and only has a few data points outside of Earth's viewing capability. That said, the source does not provide a value for maximum reflectance based on their model.</p>
<p><a href="https://i.sstatic.net/hiFca.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/hiFca.jpg" alt="Robotic Lunar Observatory data, Reflectance vs Phase Angle" /></a>
Robotic Lunar Observatory data, Reflectance vs Phase Angle</p>

CC BY-SA 4.0
2023-06-29T20:02:08.453Z
The "one data set" link is broken
Ruslan
CC BY-SA 4.0
2021-03-31T07:24:29.800Z
2021-03-31T07:24:29.800Z
nflemming2004
<p>This <a href="https://astronomy.stackexchange.com/a/43187/7982">thorough answer to <em>How long does lunar opposition surge last? Are there measurements of the full Moon getting suddenly brighter?</em></a> details observations of lunar opposition surge by the <a href="https://en.wikipedia.org/wiki/Clementine_(spacecraft)" rel="nofollow noreferrer">Clementine</a> and <a href="https://en.wikipedia.org/wiki/Lunar_Reconnaissance_Orbiter" rel="nofollow noreferrer">Lunar Reconnaissance orbiter</a>.</p>
<p>But we don't have to go to lunar orbit to see the sunlit Moon, we can observe the lunar disk right here on Earth.</p>
<p><strong>Question:</strong> Has lunar opposition surge ever been observed from Earth? From Earth orbit?</p>

CC BY-SA 4.0
2021-03-30T22:40:46.457Z
Your first hyperlink contains caption of _this_ question, rather than the linked one.
Ruslan
CC BY-SA 4.0
2021-03-30T22:57:00.577Z
@Ruslan ah I see, thanks! Feel free to edit errors anytime yourself if you feel like it.
uhoh
<the-moon><astrophysics><optics><apparent-magnitude><planetary-science>
Has lunar opposition surge ever been observed from Earth? From Earth orbit?
uhoh
# Has lunar opposition surge ever been observed from Earth? From Earth orbit?

(Asked by: username_0 on 2021-03-30)

This [thorough answer to *How long does lunar opposition surge last? Are there measurements of the full Moon getting suddenly brighter?*](https://astronomy.stackexchange.com/a/43187/7982) details observations of lunar opposition surge by the [Clementine](https://en.wikipedia.org/wiki/Clementine_(spacecraft)) and [Lunar Reconnaissance orbiter](https://en.wikipedia.org/wiki/Lunar_Reconnaissance_Orbiter).

But we don't have to go to lunar orbit to see the sunlit Moon, we can observe the lunar disk right here on Earth.

**Question:** Has lunar opposition surge ever been observed from Earth? From Earth orbit?

**Tags:** the-moon, astrophysics, optics, apparent-magnitude, planetary-science
> **Comments:**
> **username_1**: Your first hyperlink contains caption of _this_ question, rather than the linked one.  
> **username_0**: @Ruslan ah I see, thanks! Feel free to edit errors anytime yourself if you feel like it.  

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## 1 answers

### Answer by username_2 on 2021-03-31. Score: 3 | Accepted answer

While I couldn't find any quantitative information about views from Earth or orbit down to zero phase angle (especially since views direct from Earth are limited in phase angle due to Eclipse), [this website](https://asterism.org/2019/04/12/how-bright-is-the-moon/#:%7E:text=Our%20Moon%27s%20average%20visual%20albedo,dramatically%20as%20its%20phase%20changes.&text=So%20if%20the%20full%20Moon,a%20brightness%20reduction%20of%2012x.) gives an unreferenced data point suggesting Apollo astronauts observed that a zero-phase full moon is approximately 30% (0.2 magnitudes) brighter than we can ever observe from Earth.

[This site](https://the-moon.us/wiki/Retro-Reflection_phenomena) cites a value stating that the moon's brightness at zero phase angle may be as much as 14x brighter than an ideal diffuse reflecting disk, with 40% of the increase within the last 5˚ of phase angle (which cannot be observed from Earth).

Finally, there is [one data set](https://astrogeology.usgs.gov/moon-cal/modeling/irradiance.php) I have found which seems to show the opposition surge effect, but as noted, it is not what I would consider complete, and only has a few data points outside of Earth's viewing capability. That said, the source does not provide a value for maximum reflectance based on their model.

[![Robotic Lunar Observatory data, Reflectance vs Phase Angle](https://i.sstatic.net/hiFca.jpg)](https://i.sstatic.net/hiFca.jpg)
Robotic Lunar Observatory data, Reflectance vs Phase Angle

> **Comments:**
> **username_1**: The "one data set" link is broken  

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