# Homework Help: Temperature of Mars

1. Nov 28, 2009

### Manda_24

1. The problem statement, all variables and given/known data
Estimate the temperature of Mars. Assume Mars acts as a perfect blackbody and the only heat input comes from the Sun (use necessary values from appendix)

2. Relevant equations

3. The attempt at a solution

I was doing so well until I got to this question on my homework.
I tried this: (pi)(rmars)2 / 4(pi)rsun2

for the radius of mars my book says 6370 km and the sun 6.95e5 km

2. Nov 28, 2009

### mgb_phys

Thats just one small step in the answer.

First think about what the question means:
How much power does mars recv from the sun ?
How much power must it emit (and why)
Therefore what temperature must it be?

3. Dec 1, 2009

### Manda_24

Iemitted=Q/t=eA(sigma)T4

Is this part of what I need to use to finish the question? I know what sigma is and e but I don't know what A is.

4. Dec 1, 2009

### mgb_phys

This is the power emitted by a surface of area A at temperature T

Careful - what area of mars receives energy from the sun and what area emits energy into space?

5. Dec 3, 2009

### Manda_24

Thanks for your help, I finally got it