Now, if we solve this for temperature, we will get
T = (
| α |
| ε |
| S |
| 4σ |
| ¼ |
Although the total surface area, A, of a sphere is 4πr², light rays from the sun only strike half the surface at any one time. This area, a, is effectively equal to the sphere’s cross-section, πr².
This equation is well known in astronomy, and has been used for more than 80 years to calculate the temperatures of various objects in the sky. Today, we still find it useful for measuring the surface temperatures of man-made satellites such as Telstar. Since both S and σ are known constants (in this case, we use the quantities S = 445 and σ = 0.173 × 10⁻⁸), you can see that temperature is dependent on the α/ε ratio.
Finding the Right Surface for Telstar
