Let us assume we have colonized the moon. In order to secure a water supply, we create a circular subterranean lake 400m deep, and 3000M across. Would it have tides?

No.

Yes. Gravity works both ways.

The Moon already has tidal effects in the lithosphere from effects from Earth, as does the Earth.





https://moon.nasa.gov/moon-in-motion/tides/

No, because the position of the Earth relative to a point on the surface of the Moon is constant at the scale relevant to tides.

Exactly.  Tidal forces are why it does that.  So they definitely affect the moon. But you wouldn't see tides in water the way you do on earth.

The effects would be small, but there would be tides. See my previous post.

The moon is tidally locked to the earth. You would have some tide from the sun on a 27ish day cycle

Your post indicates an effect which essentially creates geologic type formations not something that would be observed as changing levels on a pool of liquid. That pool of liquid would show a tide but it would just stay that way as far as the effects of the earth on it, at least for a very long time.

It happens monthly. It's in this paper, but it's rather dense.
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2014JE004755
Here's an excerpt:

A long period tide, but still a tide. The Moon's orbit isn't perfectly circular, and it's inclined. It experiences tides that deform the Moon to the extent that it is important to take them into account when sending spacecraft to the Moon.

Ok some wobble of the earths tide on the moon gotcha.

Tides on earth are because the face of the earth that is facing the moon is in motion.  It is also the case with the face of the earth to the sun.  The moon rotates such as the same face is always towards earth - so there would be no earth tide.  That said their would be a minimal tide caused by the sun - a very minimal one.

Let us assume we went spelunking on Earth and discovered a circular subterranean lake 400m deep and 3000M across. Would it have tides?

Yes, but so miniscule that you wouldn't notice them.  Similar to the tides in the much larger Great Lakes.

No. The moon is tidally locked to the Earth. Our tides are a result of the moon changing relative position in our sky.

If you did colonize a city or town on the moon, the Earth would never change its position in your sky.

Y'all believe in the "Moon"?

lol sheeple

What’s the temp on the moon’s surface?  Wouldn’t liquid water freeze, then sublimate slowly? Like millenia.

Or, is this a “pretend STP” and, I don’t mean Stone Temple Pilots….



I’m not an astrophysicist. So, with that out of the way:

Tides on Earth are based on the moon’s gravitational pull & the Earth’s rotation.  This pulls a bubble of water towards the moon, and the Earth’s rotation relative to land masses, makes the tides move in and out.

The tides are also affected by Earth’s local water availability, since storms & draughts impact water availability, even thousands of mile up river.  Another example of how local climate affects/contributes to tides: deserts.

Since the moon is fixed facing Earth, without axis rotation, liquids would stabilize without a moving tide relative to Earth.  Given liquid water as a lake could not exist on the moon given the environment, there’s always a theoretical chance some undiscovered moon seismologic or unique gravitation issue might cause fluid shift, but hoping for that to contribute to tidal turnover, Langmire circulation cells, and general season lake turnover for mixing of a lake, like happens on Earth likely will not happen.

ETA: damn!  I forgot the affect of the sun’s gravity—but I still stand by lack of liquid water on the moon’s surface.  Relative to the sun, there would be a tide—but nothing like Earth.  The sun’s gravitational affect while the moon is in orbit around the Earth would cause slow fluid shifting.  But it wouldn’t resemble the tides on Earth.

I need another piece of paper & No.2 pencil to show my math.

Isn’t the answer, it depends where on the earth Chuck Norris is walking?