Answer & explanation
At a normal walking pace, of course.
The official answer, with Fermi’s reasoning step by step.
Answer & explanation
Official answer
91
days
How to estimate it
Fermi’s official “Napkin math”
The way around the Earth is 40,000 kilometers, and the moon is about a quarter as wide, so call it 10,000 kilometers around. How fast do you walk? A steady 5 kilometers an hour.
- Around the moon
- ~10,000 km
- Walking pace
- ÷ 5 km/h
- 10,000 ÷ 5
- ≈ 2,000 hours
- ÷ 24
- ≈ 83 days
The way around the Earth is 25,000 miles, and the moon is about a quarter as wide, so call it 6,000 miles around. How fast do you walk? A steady 3 miles an hour.
- Around the moon
- ~6,000 mi
- Walking pace
- ÷ 3 mph
- 6,000 ÷ 3
- ≈ 2,000 hours
- ÷ 24
- ≈ 83 days
Rounded assumptions may give a slightly different estimate. The official answer above is the game’s reference value.
Source calculation & reference
- Moon's equatorial circumference (NASA Moon Fact Sheet)
- ≈ 10,921 km (6,786 mi)
- A normal walking pace
- ≈ 5 km/h (3 mph)
- 10,921 ÷ 5
- ≈ 2,180 hours
- ÷ 24
- ≈ 91 days
Reference cited by Fermi: NASA Moon Fact Sheet for the circumference
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