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Why these moon hoax people find the following type of image a 'mystery' is baffling to me. The same phenomena occurs down on earth if they bother to observe rather than guess.
From the side, the two shadows are the same length, but viewed from behind, they look different. Try it yourself. Conspiracy supporters never do, but bash on about something else instead to continue their strange fantasy.
The mountains look completely different to ours... this is because they formed through different processes. Ours largely form via plate tectonics, the moon's mountains form due to other processes. Ask a lunar geologist or get a book on it. We have many of the answers now as astronauts have been there!