13 March 1610
Waning Gibbous, 86% lit
The Moon stops being perfect
Galileo published drawings of a Moon with mountains, valleys and a ragged, shadowed terminator, not the flawless sphere philosophy required.
His training as an artist mattered: he understood shadows well enough to calculate the height of lunar mountains from their length. The same little book announced four moons orbiting Jupiter, which was worse news for the old cosmology.
- Date
- 13 March 1610
- Moon computed for
- 12:00 local time, UTC+0:49The time of day is not recorded here, so noon stands in.
- Phase
- Waning Gibbous
- Illuminated
- 86%
Source: Galileo, Sidereus Nuncius (1610)