why does the moon on the left look like a peeled orange?
The moon on the right looks like a photo taken from a microscope. It looks very flat. One would expect the edges to show curvature.
Well a microscope and telescope are optically very similar, so no surprise. The current theory, as I understand it, is that after the moon formed, much closer to the earth than it is today, it quickly became tidally locked to the earth, after about 10 million years. Quickly on a geological timescale.
Tidally locked means that it always keeps the same face towards the earth. The moon actually wobbles a bit, so that we actually get to see about 55% of its surface from earth. Search on the term “lunar libration”. At the time it became tidally locked, the moon was orbiting faster and earth rotating faster than nowadays. The tidal tugs of earth on the moon, even today, causes the moon to drift further and further away and the earth to rotate more slowly. At the current time, the moon moves away from the earth at about an inch a year and the earth is slowing down by about 0.0015 seconds per century. In the time of Christ, days were about 0.03 seconds shorter than today. The definition of the second in terms of atomic clocks was calibrated to match one part in 86400 of the mean solar day in 1900! Which is why we have leap seconds today!
Fun fact: Pluto and Hydra are the only two bodies in the solar system known to be mutually tidally locked.
It is believed that the near side of the moon, the side facing us, was partially protected from meteor strikes by the earth. A meteor approaching the moon from the earth-side would encounter Earth with its 81 times stronger gravitational field first and be deflected, as often as not straight into the earth! The far side of the moon was afforded no such protection.