Planets - Effective Temperature vs Actual Temperature

In summary, the actual mean temperature of the moon is significantly lower than its effective temperature due to the lack of atmospheric effects and the way albedo is factored into the calculations. The moon's actual temperature is affected by its low albedo, even though it is taken into account in the formula.
  • #1
ExcessRed
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Why is the actual mean temperature of the moon so much lower than the effective temperature?

NASA lists the effective temperature of the moon at 270.6 kelvin.
The mean temperature of the moon at the equator is 220 kelvin.
With no atmospheric effects, why is the surface temperature so much lower than the effective temperature predicts?

Rephrasing for clarity:
What factor is NOT part of the effective temperature formula that so dramatically affects the actual temperature of the moon?

Normally one would say atmospheric effects, but the moon effectively has no atmosphere - certainly not enough of one to cause this big of a discrepancy.
 
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  • #2
ExcessRed said:
Why is the actual mean temperature of the moon so much lower than the effective temperature?

NASA lists the effective temperature of the moon at 270.6 kelvin.
The mean temperature of the moon at the equator is 220 kelvin.
With no atmospheric effects, why is the surface temperature so much lower than the effective temperature predicts?

Rephrasing for clarity:
What factor is NOT part of the effective temperature formula that so dramatically affects the actual temperature of the moon?

Normally one would say atmospheric effects, but the moon effectively has no atmosphere - certainly not enough of one to cause this big of a discrepancy.

I think Albedo, i.e. how much of the radiation is reflected by the body, is ignored when calculating the effective temperature.
 
  • #3
Actually, the two formulas I have seen that determine the effective temperature use albedo as a factor - I should have mentioned that.

I have to plug in an albedo of around .34 for the moon to come up with an effective temperature of 220, whereas the moon has an albedo around .11
 

1. What is the difference between effective temperature and actual temperature of a planet?

The effective temperature of a planet is the temperature that an idealized black body object would have if it emitted the same amount of radiation as the planet does. It takes into account the distance of the planet from its star and its albedo (reflectivity). On the other hand, the actual temperature of a planet is the temperature measured on its surface, which can vary based on factors such as greenhouse gases, atmospheric composition, and surface features.

2. Why is the effective temperature important for studying planets?

The effective temperature is important because it gives us a way to compare the temperatures of different planets, even if they are at different distances from their stars. It also helps us understand the potential habitability of a planet by giving us an idea of its energy budget.

3. How do scientists calculate the effective temperature of a planet?

Scientists use a combination of the planet's distance from its star, its albedo, and the amount of energy it receives from its star to calculate the effective temperature. This is typically done using mathematical models and computer simulations.

4. Can a planet's actual temperature be lower than its effective temperature?

Yes, a planet's actual temperature can be lower than its effective temperature. This can happen if the planet has a thick atmosphere with strong greenhouse effects, which can trap heat and raise the surface temperature above what the effective temperature would suggest.

5. How do variations in a planet's effective temperature affect its climate?

Variations in a planet's effective temperature can have a significant impact on its climate. A higher effective temperature can lead to a hotter, more hostile climate, while a lower effective temperature can result in a colder, more habitable climate. This is why the effective temperature is an important factor to consider when studying the potential habitability of a planet.

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