B What would it be like on Earth if it were not a sphere?

[rootone]

Do you think the water surface would appear flat or would you see the radius out in front of you

I think it would appear flat in your immediate locality, but beyond that it could be just about anything,
depending on what topology your planet has if it isn't a sphere.
A donut shaped planet is gravitationaly feasible, even if it is extremely unlikely.
In this case the water in the distance could appear to be at a higher elevation than you are, and the most distant water above your head.

 

[DaveC426913]

Do you think the water surface would appear flat or would you see the radius out in front of you; with the water on the far side almost over head or as a vertical wall?

Thing is, in order have such strong surface curvature you need large gradients (otherwise you wouldn't have two surfaces at different angles so close together), and thus there's got to high gravity in there somewhere.

Which makes it more problematic to have solid structures so tenuous.

You sortta can't have your cake and eat it too.

 

[DrStupid]

A donut shaped planet is gravitationaly feasible, even if it is extremely unlikely.

Is such a donut shaped hydrostatic equilibrium stable? Otherwise it would not only be unlikely but impossible.

 

[gfwhell]

There can be tides from the sun and maybe from a moon. But in order to keep the system stable they must not be strong enough to slow down the rotation significantly. In that case tidel forces wouldn't be sufficient to increase vulcanic activity directly (in contrast to Io) but maybe for plate tectonics. That leads to the next question: How would plate tectonics looks like on such a planet?

It would seem the gravitational effects on our planet from the rest of our solar system and beyond are proving to be irregular.
This is due to our short period of record keeping.
The tidal effects, torture the tectonic plates causing the eruption of volcano’s above and below sea level.
This means that 7/5ths of the worlds volcano’s are underwater. When they erupt they don't seem to effect us very much, other than raising the temperature a degree or two and poison the ocean, killing the coral and sea life, not forgetting the warming of the atmosphere.

 

[DaveC426913]

... 7/5ths of the worlds volcano’s are underwater.

 

[davenn]

It would seem the gravitational effects on our planet from the rest of our solar system and beyond are proving to be irregular.
This is due to our short period of record keeping.
The tidal effects, torture the tectonic plates causing the eruption of volcano’s above and below sea level.
This means that 7/5ths of the worlds volcano’s are underwater. When they erupt they don't seem to effect us very much, other than raising the temperature a degree or two and poison the ocean, killing the coral and sea life, not forgetting the warming of the atmosphere.

I'm seriously trying to figure out how to make sense of that post ?

 

[Vanadium 50]

This means that 7/5ths of the worlds volcano’s are underwater.

And the other negative 2/5ths?

 

[pinball1970]

Review the image in post 10 and my description of it in post 11.

Mostly what happens is that you feel like you are standing on a hillside, no matter where on the body you are (except the poles, it'll feel normally flat there). Near the poles, it'll be a gentle slope getting steeper and steeper as you near the mid latitudes.

As you approachet the waist, the last few metres would feel like a rapdily steepening slope, until you were slipping down a vertical cliff, with another cliff rising opposite you.

All free water would run toward - and pool at - the waist.
It would be kind of cool to swim from G to E. The water's surface in front of you would rise up like a vertical 90 degree wall. But as you swam toward it, you'd always feel the surface is flat where you are - while the wall in front of you flattened out, and the water behind you rose up to a wall.

That is crazy! They should make a film based on a binary planet, the CGI people would have a blast.

 

[AZFIREBALL]

In relationship to gfwhell's post of 8/13/2019 at 7:29 PM
davenn said: "I'm seriously trying to figure out how to make sense of that post ? "
I am having the same problem understand what it is he is trying to say related to the original proposition.
@gfwhell: Care to enlighten us?

 

[Umang Soni]

Something similar is actually possible if the two bodies are attached at the equator. Such configurations are known for stars (contact binaries) and should also be possible for planets.

but then Earth would still be sphere ...please clear your question

 

[Bystander]

https://www.physicsforums.com/threa...s-with-your-what-if-question-comments.975547/

 

[DrStupid]

but then Earth would still be sphere

No, it wouldn't. See in #14 how that reather looks like.
I am currently working on a solution for somewhat realistic mass distributions. But that will take some more time.

...please clear your question

Which question?

 

[DrStupid]

Now my calculation got a step forward. The shape in #14 is the isosurface of the effective potential of two orbiting point masses in their common rest frame. Of course it makes not much sense that the entire mass of the body is concentrated in two centers, but it was easy to calculate. Now I managed to describe a system where only a part of the mass is located in the centers (representing large spherical iron cores) and the rest is homogeneous distributed inside the isosurface. Here is a comparison of the two resulting shapes:

In order to get a stable equilibrium I increased the size of the cores by 500 km (compared to Earth). Stability requires that the surface potential increases with the size. In case of a non rotating sphere this would be the case when the surface density is below 1/3 of the average density. For a fast rotating system there seems to be another limit but the basic principle is the same: the bigger the cores the better.