Question

Pluto has mean diameter of 2,300 km and very eccentric orbit (oval shaped) around the Sun, with a perihelion (nearest) distance of 4.4 × 10⁹ km and an aphelion (farthest) distance of 7.3 × 10⁹ km. What are the respective solid angles subtended by Pluto from Earth’s perspective? Assume that distance from the Sun can be neglected.

Answer 1

Given: Radius of Pluto. R = \(\frac{2300}{2}\) km

= 1150 km

Perihelion distance r_p = 4.4 × 10⁹ km

Aphelion distance r_a = 7.3 × 10⁹ km

To find: Solid angles (dΩ_p and dΩ_a)

Solid angle at perihelion distance is 2.146 × 10^-13 sr and at aphelion distance is 7.798 × 10-¹⁴ sr.