h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Entry: Why the Far Side of the Moon Looks Different - A638994
Author: Gnomon - It's Time for a Change - U151503

An interesting new theory about the Moon.

I like this entry
I won't comment on the science, but it just goes to show that what is incorrectly called the 'Darkside of the Moon' was, in fact, the dark side after all (as it never received the intense earthlight).

<BB<

Well spotted. I decided not to mention that. Even mentioning the 'dark side' will further reinforce the myth that there is a dark side.

Interesting topic

{because volume depends on the cube of diameter}

I prefer 'varies with'

{The same effect is seen with other some other moons...}

Repetition

Icy

Thanks, Icy. I've tweaked both of those points.

Hi Gnomon

Thanks for writing this

"Luna 3" should be in italics.



At the time of the asteroid bombardment, the harder part would have been solid rock while the inner softer part would have been still liquid. I know what you mean but "would have been still liquid" doesn't sound right - "would still have been liquid." sounds better



Extra h2g2 Links: Phobos A50670092 - Mars A330823 - Jupiter A402003 - The Diversity of Moons A61808808


GB

Thanks GB. I've done all those suggestions.

I enjoyed this - and learned something.

You say they Moon was much closer to the Earth when all this was happening. Does anybody have an idea how far apart the two bodies were/ Just curious.

Apparently the Moon formed just beyond the Earth's fluid Roche limit. This is the limit inside which the Earth's gravity will pull apart any moon. Now I just need to look that up...

Yes, the fluid Roche limit is about 18,000km.

So I'll guess that in the early days of the Earth/Moon system, the centre of the moon was about 20,000km from the centre of the Earth. Since the radius of the Earth is 6,400km and the Moon's radius is 1,700km, the surface of the Moon would have been about 12,000km from the surface of the Earth, as compared with its current distance of 375,000km.

That would have been a truly awesome view

Yes, it would , indeed. Thanks for explaining!

I think I'll leave out all those calculations, but mention that the Moon would have been about 20 times as close to the Earth.

Couldn't have been much closer.

If it had been any closer, the Earth's gravity would have torn it apart or more accurately would have prevented it from ever forming. Presumably there were lumps of rock thrown up which were within the Roche limit. These would have not clumped together to form the new moon but would have stayed as separate lumps. Gradually colliding with each other until they either drifted outwards or fell back to earth.

Can you be 20 times as close to something? Stop me if I'm being pedantic here, but closeness is the inverse of farness. You can be 20 times further away, but wouldn't you be one twentieth as close?

...1/20th... ...as far... as distant...

I don't see a problem with being 20 times as close, but I understand that it sounds strange to some people, so I'll change it.

Actually, I didn't say "twenty times as close" in the entry, I said "it was very close to the Earth, about one twentieth of the distance it now is. "

So that should be ok.

Thanks Gnomon.

It's just a phrase that grates. I accept that everyone understands what it means.

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