Question

In preparation for a landing on the bright side of the moon, surface temperature of moon has to be estimated. Assume Lunar surface material is a good insulator. It is given that solar constant is 1353 watts/m².

Assume absorptivity and emissivity of moon is same. Approximate surface temperature of moon is

(stefan's constant = 5.67 × 10^–8Wm^–2K^–4) -

• A. 120⁰C
• B. 300⁰C
• C. 500⁰C
• D. 720⁰C

Answer 1

Answer: (A)

120⁰C

Answer 2

At equilibrium

Rate of emission = Rete absorption

esT⁴ = aI₀ …(i)

where e = emissivity of moon

a = absorptivity of moon

I₀ = solar constant.

given that e = a

sT⁴ = I₀

T =$\left( \frac{I_{0}}{\sigma} \right)^{1/4}$= $\left( \frac{1353}{5.67 \times 10^{–8}} \right)^{1/4}$=393 K = 120⁰ C