[Pseudoscience-is-malarkey (OP)]

When we first observed it in 60 years ago, what was the most fascinating and/or shocking thing about it?

[evan_au]

The most shocking thing for Americans was that the first photo of the far side of the Moon was taken in 1959 by the Russians.

The USA was terrified that the Russians would plant a flag there, and claim the Moon for Russia - a giant Hammer and Sickle (Moon) in the sky...
See: https://en.wikipedia.org/wiki/Far_side_of_the_Moon#Early_exploration

But the Outer Space Treaty in 1967 declared that no nation could own a part of the Moon (or space in general).
- So in 1969, the USA could plant a flag on the Moon, but not claim it as their own.
See: https://en.wikipedia.org/wiki/Outer_Space_Treaty

[Bored chemist]

When we first observed it in 60 years ago,

It was only released in 1973.

[Janus]

In terms of its appearance, it was that the far side of the Moon looked so different than the near side. Much more heavily cratered and lacking in "seas" or Maria.

[A-wal]

In terms of its appearance, it was that the far side of the Moon looked so different than the near side. Much more heavily cratered and lacking in "seas" or Maria.

Presumably because it's tidally locked and the Earth acts as a shield for the side we can see.

[Pseudoscience-is-malarkey (OP)]

That it wasn't dark?

Ah, you don't think we (Americans) even landed on it?

[evan_au]

because it's tidally locked and the Earth acts as a shield for the side we can see.

A recent theory suggests that the Moon was formed in a collision between the Earth and a Mars-sized planet called Theia.

The Moon formed from the debris sprayed into space from the collision.
- Both Earth and Moon would have been turned into liquid rock by the huge impact (and some parts vaporized).
- The Moon was initially much closer to the Earth, and so it rapidly became tidally locked
- The side of the Moon facing the Earth was subjected to continuous heat from the molten Earth, and took much longer to cool.
- In the cooling process, lava flows covered much of the near side of the Moon, filling in many craters. However, the far side solidified quickly, and retains a record of the many early impacts.
See: https://en.wikipedia.org/wiki/Giant-impact_hypothesis
https://en.wikipedia.org/wiki/Theia_(planet)

[Bored chemist]

That it wasn't dark?

Ah, you don't think we (Americans) even landed on it?

No, he probably just realises that the far side of the Moon isn't dark. We can't see it from here, but that's because the Moon is in the way, not because it lacks illumination.

[A-wal]

because it's tidally locked and the Earth acts as a shield for the side we can see.

A recent theory suggests that the Moon was formed in a collision between the Earth and a Mars-sized planet called Theia.

The Moon formed from the debris sprayed into space from the collision.
- Both Earth and Moon would have been turned into liquid rock by the huge impact (and some parts vaporized).
- The Moon was initially much closer to the Earth, and so it rapidly became tidally locked
- The side of the Moon facing the Earth was subjected to continuous heat from the molten Earth, and took much longer to cool.
- In the cooling process, lava flows covered much of the near side of the Moon, filling in many craters. However, the far side solidified quickly, and retains a record of the many early impacts.
See: https://en.wikipedia.org/wiki/Giant-impact_hypothesis
https://en.wikipedia.org/wiki/Theia_(planet)

I knew about the Theia/moon theory but didn't know it had anything to do with the different aspects of the two sides of the moon. Last I heard there were problems with that model andthey were trying to solve it with a double impact.

Interestingly I've heard it argued that they are actually nine planets in the Solar system and the moon is one of them because it's so big compared to us that it doesn't just cause a wobble, it causes us to both orbit the centre of gravity between us that's well away from the Earth, making us a dual planetary system. We have nine planets after all.

[Halc]

Interestingly I've heard it argued that they are actually nine planets in the Solar system and the moon is one of them because it's so big compared to us that it doesn't just cause a wobble, it causes us to both orbit the centre of gravity between us that's well away from the Earth, making us a dual planetary system. We have nine planets after all.

The center of gravity of the Earth-moon system is about 25% of the way down to the center of Earth, not well away from Earth.

[A-wal]

Interestingly I've heard it argued that they are actually nine planets in the Solar system and the moon is one of them because it's so big compared to us that it doesn't just cause a wobble, it causes us to both orbit the centre of gravity between us that's well away from the Earth, making us a dual planetary system. We have nine planets after all.

The center of gravity of the Earth-moon system is about 25% of the way down to the center of Earth, not well away from Earth.

Oh really. Well I've still heard it argued that it should be classed as a planet because of its size compared to Earth.

Only 25% of the way down to the center of Earth, the moon is 25,000 miles away and more than a quarter of Earth's size. It must be made of cotten wool.

[Bored chemist]

Interestingly I've heard it argued that they are actually nine planets in the Solar system and the moon is one of them because it's so big compared to us that it doesn't just cause a wobble, it causes us to both orbit the centre of gravity between us that's well away from the Earth, making us a dual planetary system. We have nine planets after all.

The center of gravity of the Earth-moon system is about 25% of the way down to the center of Earth, not well away from Earth.

Oh really. Well I've still heard it argued that it should be classed as a planet because of its size compared to Earth.

Only 25% of the way down to the center of Earth, the moon is 25,000 miles away and more than a quarter of Earth's size. It must be made of cotten wool.

Pardon?

[Janus]

Interestingly I've heard it argued that they are actually nine planets in the Solar system and the moon is one of them because it's so big compared to us that it doesn't just cause a wobble, it causes us to both orbit the centre of gravity between us that's well away from the Earth, making us a dual planetary system. We have nine planets after all.

The center of gravity of the Earth-moon system is about 25% of the way down to the center of Earth, not well away from Earth.

Oh really. Well I've still heard it argued that it should be classed as a planet because of its size compared to Earth.

Only 25% of the way down to the center of Earth, the moon is 25,000 miles away and more than a quarter of Earth's size. It must be made of cotten wool.

More than a quarter in size in terms of diameter, but that equates to ~ 1/50 in terms of volume.  The Moon is, over all, less dense than the Earth, at 3.34 g/cc vs 5.52 g g/cc, or about 60%, which results in the Moon having roughly 1/81 the mass of the Earth.