Question

what is the solid angle subtented by the moon at any point of the earth, given the diameter of the moon is 3474 km and it's distance from the earth 3.84×10^8 m
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Answer 1

Answer:

Diameter of moon = 3474 km.

Therefore, radius is 1737 km. The area will be,

A_m = x pi r^2 = (3.14)(1737)^2 = 9.473 x times 10^6 m^2

The distance from the Earth is given as,

= 3.84 x 10^8 m

Squaring this value,

r^2 = (3.84 x 10^8)^2 = 14.74 x10^{16} \ m^2

Now the solid angle in steradians is,

And that should be the answer.