Roche limit

Thats how close a planet can get to another planet before it breaks up by the combination of gravity and tidal forces.
So what if the planets were 12,000 Km wide diamonds? Is there anything strong enough to let such a system orbit a few klicks apart, no atmosphere on either planet.

The beginning sounds interesting, but I don't understand the last sentence. Therefore I don't know what to do. 😉

Originally posted by crazyblue
The beginning sounds interesting, but I don't understand the last sentence. Therefore I don't know what to do. 😉

I'll try to translate.

Thats how close a planet can get to another planet before it breaks up by the combination of gravity and tidal forces.
So what if the planets were 12,000 Km wide diamonds? Is there anything strong enough to let such a system orbit a few klicks apart, no atmosphere on either planet.

"The Roche Limit" is how close a planet can get to another planet before it breaks up due to gravity and the associated tidal forces.
Is there any conceivable substance (for example, pure diamond) that is strong enough to make a planet out of such that the planet's Roche Limit is less than a few km? If it matters, assume that there's no atmosphere on either planet.

Originally posted by AThousandYoung
I'll try to translate.

[b]Thats how close a planet can get to another planet before it breaks up by the combination of gravity and tidal forces.
So what if the planets were 12,000 Km wide diamonds? Is there anything strong enough to let such a system orbit a few klicks apart, no atmosphere on either planet.

"The Roche Limit" is how close a ...[text shortened]... t is less than a few km? If it matters, assume that there's no atmosphere on either planet.[/b]

I've been to restaurant's like that. Get you real close, but then it turns out they have no atmosphere.

Originally posted by Gastel
I've been to restaurant's like that. Get you real close, but then it turns out they have no atmosphere.

Just like Armstrong found out about the moon! Nice place to visit but no atmosphere.
So how 'bout it? Lets say its two diamond planets, perfectly spherical, no atmosphere, could they get within a few Km of each other at perigee in the orbit and not break up? (Perigee, closest approach in in orbit)

i don't have a clue, but diamond planets 12 KM dia and no atmosphere wouldn't have any tides, so it must have everything to do with a calculation of shear forces and calculation of gravity. the calculations are easy, so i'm going to guess that no known molecular structure is strong enough to withstand the gravitational shear force of two 12 KM dia orbs that are so close together that they are "almost touching" as far as the calcs go

Originally posted by coquette
i don't have a clue, but diamond planets 12 KM dia and no atmosphere wouldn't have any tides, so it must have everything to do with a calculation of shear forces and calculation of gravity. the calculations are easy, so i'm going to guess that no known molecular structure is strong enough to withstand the gravitational shear force of two 12 KM dia orbs that are so close together that they are "almost touching" as far as the calcs go

The forces would be even stronger, I was talking about a 12,000 Km wide planet not a 12Km sized one. In other words, earth size
There are BTW indications of masses of diamond that large, there are speculations that an odd star has the spectral signature that is matched by diamond! The sheer resistance of diamond is incredible.

Originally posted by sonhouse
The forces would be even stronger, I was talking about a 12,000 Km wide planet not a 12Km sized one. In other words, earth size
There are BTW indications of masses of diamond that large, there are speculations that an odd star has the spectral signature that is matched by diamond! The sheer resistance of diamond is incredible.

It's one solid molecule. Diamond is amazing. Carbon - the same nonmetal we're made of - harder than steel!

I always wonder what the outside of the diamond is like on the molecular level. The outer carbon atoms would not have the proper tetrahedral set of four bonds; what happens to the unbonded electrons? Is the outside oxidized or something?