ID:154168
 
Now that I've embarassed myself with easy math questions (well, easy for some of you at least), I figured I'd ask some more.

In our solar system, we have 9 planets (irrelevant fact, woohoo!). Mercury, the closest, is roughly 0.3 AUs from our star and is 600 degrees at its peak. Pluto is the furthest from our star, at roughly 40 AUs, and averages -350 degrees.

Now, the problem is that, how can you calculate the temperature of a planet (regardless of atmosphere) based on its distance from the star?

I'm lost on this, so if anyone can help...
Foomer wrote:
Now that I've embarassed myself with easy math questions (well, easy for some of you at least), I figured I'd ask some more.

In our solar system, we have 9 planets (irrelevant fact, woohoo!). Mercury, the closest, is roughly 0.3 AUs from our star and is 600 degrees at its peak. Pluto is the furthest from our star, at roughly 40 AUs, and averages -350 degrees.

Now, the problem is that, how can you calculate the temperature of a planet (regardless of atmosphere) based on its distance from the star?

I'm lost on this, so if anyone can help...

You can't calculate temperature directly, but you can calculate the amount of light/radiation received:

k/d2
k is a constant
d is the distance from the star in AUs

Now, a certain percentage of this will be reflected: This is the planet's albedo. What isn't reflected is absorbed by the planet, and that depends on its composition.

Another factor is temperature variation. This depends on the rotational speed of the planet (the slower it rotates, the more time it spends in sunlight or shadow at a stetch) and on its atmosphere. Generally speaking, I think more atmosphere would cause more stability in temperature. (Venus has a thick atmosphere, but not much temperature stability because it only completes a full rotation every 9 months.)

Lummox JR