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Robert Walker

All the Apollo landings were done during a waxing crescent phase, first quarter. They needed to land when the light was at the right angle. Apollo 11 had to land during a narrow time window of sixteen hours every 29.5 days, so that they could see the lunar features during the descent flight path to the Moon. They could only land when the sun was at an elevation of between 5° to 14°. Too high and the sun would be directly behind them so that they couldn't make out any shadows at all, the landscape would be "washed out". Too low and most of the landscape would be shadowed.

It was also easier to do it in the early morning, before it gets too hot. Leaves plenty of time also, sun not going to set for many days. If they’d landed in the late evening on the Moon that would have meant it was getting darker and colder the longer they stayed.

Since they landed near the center of the Moon and somewhat towards the side that the sun lights up first (right hand side as seen from Earth’s northern hemisphere), that makes it a waxing crescent phase.

Apollo 11 Moon Landing: How It Worked (Infographic)

This is even more of an issue at the lunar poles. Probably won’t be able to do visual landings there. Long shadows on the Moon, especially at the poles

About the Author

Robert Walker

Robert Walker

Writer of articles on Mars and Space issues - Software Developer of Tune Smithy, Bounce Metronome etc.
Studied at Wolfson College, Oxford
Lives in Isle of Mull
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