# Stellar Astronomy - Measuring surface temp of the Sun

1. Oct 2, 2011

### PsychoDash

1. The problem statement, all variables and given/known data

"Determine a surface temperature value for the Sun from the angular diameter of the Sun and the solar constant."

2. Relevant equations

L=4π(R^2)σT^4

3. The attempt at a solution

At this point my only stumbling block is I don't understand the relationship between the solar constant and luminosity.

edit: Is it as simple as multiplying by the square of the distance?

2. Oct 3, 2011

### Cipherflak

The units of the different sizes tells a lot, actually.

Keep in mind that the solar constant on earth is just a wee bit of the total energy radiating from the sun, that is the luminocity. Picture a large sphere with the distance between the sun and earth as a radius; the solar constant applies to to everywhere in this sphere, so you must actually multiply with the area og this sphere to get the luminocity. Then you can use Placks equation to get the temperature.