Moon · 5 of 8
The Moon Illusion
Why does the rising Moon look so big?
The rising full Moon looks huge, but ring it and it is no bigger: high up it is a hair wider, because you are nearer. The air only squashes it. The size is in the mind.
You’ll be able to say why the rising Moon looks big, and show that it is not.
Where and which night
Working out when this is best placed from where you are…
Where
Kept for this guide only, until you change it here — your map settings, and every other guide, stay as they are.
Print, play outside or present
Scan with a phone's camera, or open
Sources
- NASA, "Why Does the Moon Look Larger at the Horizon? We Asked a NASA Scientist", episode 50 (2025) — not magnified, not nearer: about 1.5 percent farther away on the horizon
- Meeus, Astronomical Algorithms, 2nd ed. (1998), ch. 16 and 40 — refraction near the horizon, and the Moon's distance from a place on the Earth's surface
- Ross & Plug, The Mystery of the Moon Illusion (Oxford University Press, 2002) — known since antiquity, and still argued over
With a keyboard, focus the sky, aim it with the up and down arrow keys, and press Enter to drop the pin at the centre of the view; or press Show me.