General Question

luigirovatti's avatar

Does the following description "fit into science" about why some planets have hollow interiors?

Asked by luigirovatti (2363points) November 17th, 2020

To be exact, planets created with material ejected from a star. As a molten ball is thrown from the star and stars spinning away, it begins to cool.

The centrifugal force of the globe spinning and moving at great speed pushes the molten interior to the sides, forming the crust of the planet. This, in turn, forces hot gases out of the poles to form openings at both ends. The molten core and gases that remain get trapped between the hollow interior and the plates below the crust of the globe. These are pushed out periodically in the form of volcanic activity.

(P.S. If you notice, the nexus point of such globe seems to be always the 19th parallel, i.e. the Hawaiian volcanoes, located on that parallel, the Mons volcano on Mars, and also, the red spot on Jupiter.)

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27 Answers

Caravanfan's avatar

There is no such thing as a hollow planet. (Incidentally, there is no such thing as centrifugal force either).

luigirovatti's avatar

@Caravanfan: I don’t know if I must take you at your word (see link) or laugh it off.

zenvelo's avatar

@luigirovatti From Encyclopedia Britannica::

“Centrifugal force, a fictitious force, peculiar to a particle moving on a circular path, that has the same magnitude and dimensions as the force that keeps the particle on its circular path (the centripetal force) but points in the opposite direction.”

By the way @luigirovatti have you been reading science fiction again?

luigirovatti's avatar

No comment. So, are you saying we can’t experiment with centrifugal force to prove my point?

luigirovatti's avatar

I did a bit of research and, for that matter, even centripetal forces don’t exist. But, even in that case, that doesn’t disprove my point. We should argue about the reasoning, not the terminology.

ragingloli's avatar

A planet does not spin fast enough for that to be even remotely plausible.
It also would not be spherical, if it did. Earth rotates once every 24 hours, and as a result is a slightly oblate spheroid, meaning its diameter at the equator is larger than that from pole to pole.
A planet that hypothetically spun that fast, fast enough to overcome the gravitational force of an entire planet’s worth of molten rock and metal, would be flattened into a disk, and eventually disintegrate completely.

stanleybmanly's avatar

Hollow? The core eliminates any description as hollow. There could be a planet with an ice surface concealing liquid below it. Do you want to speculate on the possibility of space between the “shell” and lake beneath? Where did you acquire the notion of “some planets with hollow interiors?”

ragingloli's avatar

Also, even if you started with a hollow planet with openings at the poles, that span fast enough for that, that speed would only apply to the region closest to the equator. The rest would promptly fall intwards to its shared center of gravity.
What then might happen is that the polar apertures may widen as the planet collapses towards the rotational plane, resulting in a rapidly spinning, non-hollow donut.
Or the apertures might close up, too, where you end up with a another disk.
Or the outer shell is ripped apart into 2 or more parts, the inner of which would collapse in on itself and form a non-hollow sphere, surrounded by one or more disks, which may or may not fall onto and merge with the sphere.

In any case, a hollow planet is impossible, unless it is an artificial construct, built by an advanced alien race.

Caravanfan's avatar

@ragingloli “built by an advanced alien race.”. Which you, of course, are from.

stanleybmanly's avatar

Advanced but by no means benign.

ragingloli's avatar

We do not just build “hollow planets”, because that would be a colossal waste of space.
We build them like onions, with thousands of layers of surfaces on the inside.

Tropical_Willie's avatar

Are you calling off Gravity ?

Have you heard about accretion processes ? It is how planets are formed. Hollow planets don’t fit into science.

Zaku's avatar

No, the description of the process in this question doesn’t match actual astrophysics.

If there were a blob of molten material ejected, it would not be spinning at high speed, and molten blobs are molten, not solid, so there’s no structure to spin and no reason it would have a greatly uneven force to spin it at high speed.

And if some collision or uneven force did spin a liquid or molten blob so quickly that the matter would move away from its center of mass, it would tend to either keep moving away from its center of mass, or collapse back together.

Some matter of exactly the right combination of mass, viscosity, and energy state might possibly form a bubble, and it is possible such a bubble might cool into a solid bubble. However that would not be the usual situation, by a long shot. Most matter from erupting suns is gas, particles, and molten streams.

The process of forming planets by accretion into planetary blobs involves vast amounts of matter accumulating due to gravity and matter interacting with other matter to cancel out velocity. Gravity is a very weak force, so it takes a lot of mass to do that, and results in large solid-cored spherical bodies, and asteroid belts, and some small stuff like comets, independent asteroids, and the Oort cloud.

Anything large enough to be a round planet has so much gravitational force that any large-scale deformities (more severe than a canyon or mountain) will be collapsed by gravity into rougly a sphere shape.

Even if you somehow wished into existence a spinning sphere-planet, it wouldn’t be a sphere or it would collapse, because inertia would only keep certain latitudes in statis – the others would collapse and at best you’d have an asteroid disc, or more likely, a spherical planet.

Dutchess_III's avatar

Man everything in the universe, including us, is created from material ejected from a star. However when they go nova they don’t throw off “balls” that cool into planets. Read up here
Also, there is no such thing as a hollow planet. If it was hollow it would be busted into a million pieces when it got smacked with asteroids.

Darth_Algar's avatar

@luigirovatti “As a molten ball is thrown from the star and stars spinning away, it begins to cool.”

What? Are you under the impression that stars are big balls of lava or something?

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Caravanfan's avatar

Centripetal force is a true force that is orthogonal to the rotational motion. Centrifugal force is the fictitious force that is felt by the object, but it’s not a true force.

But that’s neither here nor there. Planets are not hollow.

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Dutchess_III's avatar

Wait…isn’t centrifugel force the force that keeps water in a spinning bucket, even when the bucket is spun upside down?
Isn’t centrifugel force the thing that keeps a motorcycle on its feet even with a dumbass driving it?

gondwanalon's avatar

Name a planet that has a hollow interior.

The center of a planet is the focal point of it’s disruption of the space time continuum. In other words the center of a planet is the focal point of gravity that hold the planet together. This is why the center of planets and moons is made of a core of very dense material. This is the exact opposite to the situation that you suggest.

LuckyGuy's avatar

To make a sphere you would need to spin the molten ball evenly in all axes. If it spun in one in axis the blob would stretch out into disk-like shape. How and why would a planetary ball continuously change its spin axis with no outside forces?
Planets are formed by accretion. Some particles combine and their gravitational force attracts other particles which increases the mass and increases the gravitational forces which attracts more particles which…. The process slowly builds up.
There is no evidence of a hollow planet.

Tropical_Willie's avatar


“How and why would a planetary ball continuously change its spin axis with no outside forces?” It couldn’t while rotating, a gyroscope rotates and fights changing the position and rotation.

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