<p>You don't say how you got your average temperature. If it is a straightforward average, then I think I have your answer.</p>

<p>The temperature of the moon is highly non uniform, ranging from around 100 K on the night side to 370 K on the sunlit side. This gives a crude average of 235 K.</p>

<p><a href="https://space.stackexchange.com/questions/3290/what-is-the-temperature-variation-between-the-lunar-day-and-night-on-the-moon">https://space.stackexchange.com/questions/3290/what-is-the-temperature-variation-between-the-lunar-day-and-night-on-the-moon</a></p>

<p>However, in terms of blackbody radiation, if we treat both hemispheres as separate blackbodies, then together they radiate as much energy as a hotter blackbody because of the $T^4$ factor in Stefan's law. The "effective temperature" will be 
$$ T \simeq (0.5\times 100^4 + 0.5\times 370^4)^{0.25}= 311\ K$$
So this is more like your equilibrium temperature and a more appropriate area weighting and/or tweaks to the exact range of temperatures could bring it into close agreement.</p>

CC BY-SA 3.0
2015-10-14T00:04:40.150Z
got my average surface temperature of 220k from Wikipedia (i know, sorry). their citing was a 1999 article in Icarus magazine
Jack R. Woods
CC BY-SA 3.0
2015-10-13T23:05:30.120Z
2015-10-13T23:05:30.120Z
2017-04-13T12:58:55.210Z
ProfRob
<p>Using the standard formula for effective temperature of a planet, Venus has T(eff)=220K, Earth has T(eff)=255K and Mars has T(eff)=212K (using albedo for Venus a=0.7, Earth a=0.367, Mars a=0.25). Average surface temperatures of 730K, 288K and 218K respectively are easily explained by differences in greenhouse effect. The moon however with an albedo of a=0.1 should have a T(eff) of about 270K, but the average surface temperature is about 250K. 
<a href="http://en.wikipedia.org/wiki/Effective_temperature" rel="nofollow">Here</a> is where I got the T(eff) formula and <a href="http://www.asi.org/adb/02/05/01/surface-temperature.html" rel="nofollow">here</a> is where i got the average temperature of the moon. (the latter is a new citing and I have edited the mean temperature value) I have revised my planet temperatures using <a href="http://www.atmos.washington.edu/2002Q4/211/notes_greenhouse.html" rel="nofollow">this</a> reference.
What explains this negative difference?</p>

CC BY-SA 3.0
2015-10-13T15:59:18.203Z
How did you calculate the "average" temperature? It varies massively between the day and night sides. So I suspect that is your solution. Doesn't the formula you have used assume the surface has a uniform temperature? You probably need the area-weighted average of $T^4$.
ProfRob
CC BY-SA 3.0
2015-10-14T10:21:17.947Z
It would be interesting to do Mercury too, with it's slow rotation.   That should be similar to the moon-effect.  It's elongated orbit around the sun might be a little complicated to work in but average temp of 332 degrees - here:    http://www.space.com/18645-mercury-temperature.html
userLTK
CC BY-SA 3.0
2015-10-15T11:37:08.603Z
Same answer to your edited question, but the closing of the gap between the two just means that the (area-weighted) differences between min and max temperatures must be smaller. (i.e. I assumed one hemisphere is very hot and the other very cold, but in reality it will be smoother than this).
ProfRob
<the-moon>
Moon's negative greenhouse effect?
Jack R. Woods
# Moon's negative greenhouse effect?

(Asked by: username_0 on 2015-10-13)

Using the standard formula for effective temperature of a planet, Venus has T(eff)=220K, Earth has T(eff)=255K and Mars has T(eff)=212K (using albedo for Venus a=0.7, Earth a=0.367, Mars a=0.25). Average surface temperatures of 730K, 288K and 218K respectively are easily explained by differences in greenhouse effect. The moon however with an albedo of a=0.1 should have a T(eff) of about 270K, but the average surface temperature is about 250K.
[Here](http://en.wikipedia.org/wiki/Effective_temperature) is where I got the T(eff) formula and [here](http://www.asi.org/adb/02/05/01/surface-temperature.html) is where i got the average temperature of the moon. (the latter is a new citing and I have edited the mean temperature value) I have revised my planet temperatures using [this](http://www.atmos.washington.edu/2002Q4/211/notes_greenhouse.html) reference.
What explains this negative difference?

**Tags:** the-moon
> **Comments:**
> **username_1**: How did you calculate the "average" temperature? It varies massively between the day and night sides. So I suspect that is your solution. Doesn't the formula you have used assume the surface has a uniform temperature? You probably need the area-weighted average of $T^4$.  
> **username_2**: It would be interesting to do Mercury too, with it's slow rotation.   That should be similar to the moon-effect.  It's elongated orbit around the sun might be a little complicated to work in but average temp of 332 degrees - here:    http://www.space.com/18645-mercury-temperature.html  
> **username_1**: Same answer to your edited question, but the closing of the gap between the two just means that the (area-weighted) differences between min and max temperatures must be smaller. (i.e. I assumed one hemisphere is very hot and the other very cold, but in reality it will be smoother than this).  

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## 1 answers

### Answer by username_1 on 2015-10-13. Score: 2 | Accepted answer

You don't say how you got your average temperature. If it is a straightforward average, then I think I have your answer.

The temperature of the moon is highly non uniform, ranging from around 100 K on the night side to 370 K on the sunlit side. This gives a crude average of 235 K.

<https://space.stackexchange.com/questions/3290/what-is-the-temperature-variation-between-the-lunar-day-and-night-on-the-moon>

However, in terms of blackbody radiation, if we treat both hemispheres as separate blackbodies, then together they radiate as much energy as a hotter blackbody because of the $T^4$ factor in Stefan's law. The "effective temperature" will be
$$ T \simeq (0.5\times 100^4 + 0.5\times 370^4)^{0.25}= 311\ K$$
So this is more like your equilibrium temperature and a more appropriate area weighting and/or tweaks to the exact range of temperatures could bring it into close agreement.

> **Comments:**
> **username_0**: got my average surface temperature of 220k from Wikipedia (i know, sorry). their citing was a 1999 article in Icarus magazine  

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