How big can a solid object be?

[Tuor]

Just a physics/astronomy question from a simpleton. But a curious simpleton nonetheless.

The general rule of thumb seems to be that larger objects, on an astronomical scale, will have less and less mass/density.

The reason is just mass, if you had more mass then the internal pressures become higher and whille the volume decreases the density increases.

A good example is Mars Vs Mercury. Even that Mars is a lot more massive then Mercury, since Mercury is more dense the result is that they both have a similar gravitical pull at the surface. If you had more mass to a object its gravitical pull will be increased resulting in the compression of materials resulting in a higher density.

AFAIK it is our own puny little planet which is the largest rock solid object we know of.

Much more massive planets have been found, such as carbon like planets (literaly diamond) with densities around 3x the ones we have here on Earth.

Earth density is around 5.9g/cm3
Carbon like planets are around 20g/cm3

The big planets in our solar system are all gas giants, and the even larger ones we've found in other solar systems always have less mass than Jupiter.

More massive and bigger planets have been found.

Is there some kind of threshold where rocky/solid objects just can't get bigger? I am excluding black holes since at that point they just don't give a shit and live by their own rules.

Since you excluded Black holes i'll have to say that neutron stars fit in your description... Or even White dwarfs stars (dead stars)

Answering you question in a simple way. Being more massive means that that object had a bigger chance in atracting more gas during its formation, which means they would become gas planets and not rocky ones.

[Mayhem]

The crust of the earth is solid but it's mantle and core are liquids.

wut? i thought the core was solid

[Amirila]

wut? i thought the core was solid

Well, it would have been solid if it wasn't as hot as it is. The core is mainly made up by magma
*EDIT: after a quick search: it's only the outer core that's liquid, the inner is solid*

[Deleted]

The atoms from every Human would be the size of a sugar cube & would be so dense that it'd sink to the Earth's core in the blink of an eye.

[mickybrighteyes]

Eh... the mantle's more like toothpaste than a liquid. Only the outer core is thought to be liquid.

[Phaere]

It depends on how you want to classify 'big' if you want to classify it like big as in massive than a Black Hole or Neutron Star would fit that.

But if you want to classify 'big' by size than look up super Earths or a Brown Dwarf or large Jovian (Jupiter) Type planet.

Here's a pic of the inside of Jupiter:



Jupiter's core is easily much bigger than Earth is. And a Brown Dwarf will look similar to how Jupiter looks on the inside but they are 8x-80x Jupiters mass.

[Dezerte]

Somewhat relevant: http://www.universetoday.com/13757/h...o-planets-get/

[Absintheminded]

http://en.wikipedia.org/wiki/Neutron_star

[Deleted]

That's something that has always confused me, How did they decide what our earth is like inside? I've seen so many cut-away pictures and I just don't see how it's even remotely possible they could have any inclination what the earth is actually like on the inside, considering if relation the lowest/deepest points anyone has reached really isn't that far.

Thanks to the earthquakes: we know that some seismic waves cannot propagate through solids. By studying which seismic centrals detect the earthquakes and which don't, we obtain of the picture of the "shadow" in their propagation, which in turn allows us to estimate at which depth the mantle becomes not-solid. With all the seismic waves and their different velocities depending on the different plasticities of the layers of the earth, we can compose a pretty clear picture of how the mantle is. We know for sure the external core is liquid. We can only conjecture that the inner core is not all that liquid, due to its composition and pressure.

- - - Updated - - -

http://en.wikipedia.org/wiki/Neutron_star

I wouldn't consider a neutron star a "solid". It's more like a huge atomic nucleus without protons. It's not a state of aggregation of matter: water is still chemically water whether it's liquid, gas or solid... but if you turn water into neutron star stuff, it's not chemically water anymore.

[Gheld]

There. The outer portions are made of matter of no particular phase, plasma if anything and as you get towards the center it just becomes even more confusing.

So it would be more accurate to say a neutron star is a quantum-mechanical clusterfuck than to say a neutron star is "like a solid".

EDIT: What I mean of no particular phase is that in order for matter to be in a specific phase the nucleons and the electrons have to be having happy fun times together. As you can see in the diagram they had a bit of a falling out.

[Sierra85]

OP: i think the answer is, relatively big.

[Deleted]

There. The outer portions are made of matter of no particular phase, plasma if anything and as you get towards the center it just becomes even more confusing.

So it would be more accurate to say a neutron star is a quantum-mechanical clusterfuck than to say a neutron star is "like a solid".

EDIT: What I mean of no particular phase is that in order for matter to be in a specific phase the nucleons and the electrons have to be having happy fun times together. As you can see in the diagram they had a bit of a falling out.

That's probably the best description i've read so far of a neutron star XD

ETA: sigged XD

[Deleted]

If you want to get really technical, all objects are made up of smaller objects. So define 'solid object', if I were to guess your definition I'd choose a big planet.

[Wildtree]

If you want to get really technical, all objects are made up of smaller objects. So define 'solid object', if I were to guess your definition I'd choose a big planet.

I was going to ask the theoretical question whether any solid object even exists..

[haxartus]

There. The outer portions are made of matter of no particular phase, plasma if anything and as you get towards the center it just becomes even more confusing.

So it would be more accurate to say a neutron star is a quantum-mechanical clusterfuck than to say a neutron star is "like a solid".

EDIT: What I mean of no particular phase is that in order for matter to be in a specific phase the nucleons and the electrons have to be having happy fun times together. As you can see in the diagram they had a bit of a falling out.

The core structure is just a suggestion. We just don't know.
Understanding the core of a neutron star will help us understand black holes, since it's the closest thing to a black hole without being one.

[Gothicshark]

Just a physics/astronomy question from a simpleton. But a curious simpleton nonetheless.

The general rule of thumb seems to be that larger objects, on an astronomical scale, will have less and less mass/density. AFAIK it is our own puny little planet which is the largest rock solid object we know of. The big planets in our solar system are all gas giants, and the even larger ones we've found in other solar systems always have less mass than Jupiter.
Is there some kind of threshold where rocky/solid objects just can't get bigger? I am excluding black holes since at that point they just don't give a shit and live by their own rules.

At a guess large sized Carbon planet.

http://www.sci-news.com/astronomy/article00649.html

[Valort]

mercury is probably the biggest fully solid rock we know of. Don't quote me on this though, i'm not an astrologist.

I must quote you, regardless, since I was hoping for a horoscope reading from you.

OT: If the universe is infinite, then the whole size&mass question isn't "How big can it be?" or "What is the biggest?" but "What is the biggest known SO FAR?" and "How big do we theorize an object can get before losing mass as the size grows?". Simply like that.

[Dezerte]

I was going to ask the theoretical question whether any solid object even exists..

We're made up of mostly empty space (atoms have huge amounts of empty space in them, relatively speaking), if we want to get really technical.

[N-7]

That's something that has always confused me, How did they decide what our earth is like inside? I've seen so many cut-away pictures and I just don't see how it's even remotely possible they could have any inclination what the earth is actually like on the inside, considering if relation the lowest/deepest points anyone has reached really isn't that far.

1. Waves, their velocities and it is relation with density.
2. Some theory about universe composition in percentage and what not and it is relation to universe.
3. What you usually see is a simplified model of the Earth interior, nature is more complex and there are still mysteries inside the Earth (AKA the recently discovered Post-Perovskite phase and why the Earth magnetic field reverses).

And some other reasons that led to this model. I probably should have expanded on this/used correct terminology but I am too lazy to bother.

[Mongo42]

Since the question has been intelligently answered with references to mass / density and gravitational thresholds creating black holes, I'll throw in some theoretical physics / fringe science.

If the universe is expanding, then the "fabric" or quantum medium must be altering along with it by stretching. The amount of matter / energy relative to the density of the quantum medium could explain "dark matter" and odd celestial variations in perceived gravitational force. This concept explains how all the matter / energy in the universe could be in one little spot at the Big Bang without collapsing into a black hole immediately. So the question would have to take into account whether this object existed within some alteration of the quantum medium / fabric of the universe. For example, if the object were approaching a black hole, would the black hole "tearing" space time weaken things to the point that the object could then create its own black hole because of its proximity to this "tear in space"? Could that local field of gravity be a variable to consider on absolute maximum mass?

Also, if we consider Special Theory, that an object accelerating towards the speed of light has its relative mass increase towards infinite mass. If a massive object is spinning at very high speeds, could this aspect of relativity become a significant limit on its absolute mass? If a stationary relatively inert object approached the limit to becoming a black hole, could causing it to begin spinning, such as passing by some other massive celestial body, cause it to begin rotating and thus its relative mass push it over that threshold?

But the biggest question of all is, if the moon really was made of blue cheese, how big could it be before it collapsed into a black hole?