Q166
General ScienceSpace & Astronomy
The ratio of the diameters of moon and earth is nearly
- a.1 : 2
- b.1 : 5
- c.1 : 4
- d.1 : 8
Answer: (C) 1 : 4
The Moon's diameter is about 3,474 km and the Earth's about 12,742 km, a ratio of roughly 0.27, i.e., nearly 1 : 4. Related ratios worth remembering: the Moon's mass is about $\frac{1}{81}$ of the Earth's, its surface gravity about $\frac{1}{6}$ and its volume about $\frac{1}{49}$. It rotates on its axis and revolves around the Earth in the same period of about 27.3 days, so we always see the same face; its mean distance is about 3,84,400 km, and moonlight takes about 1.3 seconds to reach us.