Roche Limit Puns

This may not be the most accurate way to describe it, but I have been told that objects get ripped apart by the roche limit because they get too close to another object and the gravity from the bigger object rips them apart because their mass doesn't have enough gravity to hold itself together. Given we are much smaller and have way less gravity, why don't we get ripped apart in orbit?

If all I fear is just that limit, then why does that limit exist in the first place?

Hi, hope you are all well. When a planet, moon, etc. crosses the Roche limit of a larger, more massive body, and is torn apart, what sets the limit on how small those fragments can be, and is there a calculable lower limit on their size?

Thanks!

And what would theoretical surface temperature be?

Scientifically speaking, is it possible for a passing asteroid or other large body traveling in space, with it's own Roche limit, tear a piece away of a smaller stable body in a solar system through tidal force pulling? I'm not talking solely about Earth, but any stable body in natural orbit around another body. If a larger body traveling freely in space, with a larger mass and gravitations pull, tear parts away if the larger body passed the smaller and the smaller moved inside its Roche limit?

Just the names of the concepts would be enough. I will do the digging and learn.

I tried reading the Wikipedia article, but I'm not quite sure I understood it right. My knowledge in science in general is the one of an 8th grader. Thanks in advance.

edit: solved, thanks!

I had a goal, a simple goal: to make sense of Halo Reach’s astronomy. Well, allow me to tell you that I’ve done the exact opposite. Here is everything broken with Halo Reach’s astronomy:

First things first, let's start with something that makes sense. At first I miscalculated Reach's volume, getting a value that was 13 times that of Earth. This, paired with Reach's mass which is 1.55 that of Earth lead me to believe that the gas giant density I found could only be explained by Reach being hollowed out by the Forerunners. As u/DeathsIntent96 pointed out I made a colossal mistake. In reality Reach would have a mass 1.72 times that of Earth and a far more reasonable density of 4.96 g/cm^3. This blows the "Hollow Reach Theory" part of this post out of the water. Based on the mass and density of the planet, Reach seems to be a slightly less dense Earth-like planet with a strong dynamo effect at the core (hence the very active tectonic activity bringing titanium to the surface, and the aurora around the planet that some have theorized is due to a strong magnetic field). Always check your math kids.

Second things second, the HUD compass makes measuring approximate angular sizes of things in the skybox a lot easier. In Combat Evolved I was making approximations of the size of Threshold and Basis based on how much of the sky they take up between the horizon and the ring in the sky (the zenith). The HUD compass gives me a nice 360 degree measuring system to use for horizontal measurements, which makes measuring the angular size of Reach's moons (Csodaszarvas and Turul) a whole lot easier. I can then take those measurements, compare to the canonical dates, and try to find (1) the eccentricity of their orbits and (2) maybe some estimates of the masses/sizes of the moons.

Ok, so that didn’t go as planned. Throughout the campaign we only get 4 looks at Csodaszarvas and 3 at Turul. The angular size of Csodaszarvas ranges from about 19.8 to 27 degrees while Turul ranges from 4.5 to 8 degrees. From those numbers some things should become very apparent: these moons take up a lot of the sky, and they range in size a lot. For reference, if the moon were as close to Earth as Phobos is to Mars (9,380km) then it would take up 20 degrees of the sky, only putting it in the lower bound of Csodaszarvas. In reality the moon only takes up half of a degree in the sky and varies by 14% in diameter (as opposed to Csodaszarvas’s 35% and Turul’s insane 77.8%). The real kicker is that e

Would we feel the gravity when the moon is on our side? How would the earth look; would all the oceans be in a single band along the moons orbit? And how large would the moon appear?

I have been studying the Roche limit and its consecuences for moons or satellites trajectories, but I need to know something: What is the loss rate of mass respect to distance or in the time of these bodies that overreach the limit?

I'm pretty sure this could theoretically exist, but do we know for sure if a star exists that is so large but also has such little density that a satellite could actually orbit inside of the star without being past its roche limit? Assuming the satellite doesn't melt.

Is it possible for planets like hot-Jupiters or planets without a moon to have a Roche Limit or Hill Sphere? If so, how would one go about calculating for such world?

My thought process is that instead of wasting fuel landing on Phobos, you slow its velocity enough to get ripped apart by Mars, then you take in the dust and rocks from the rings that would form. With that method, you needn't orbit, land, take off, then land, you just orbit Mars then land.

For anyone not familiar, the Roche limit is a distance from a celestial body where if you orbit any closer, the difference in gravity literally rips you apart. (It's theorized that this is how Saturn got its rings. Bastard wears a corpse like jewelry.) Black holes however are supposed to have such strong gravitational pull that nothing can escape them. So could a large enough object (A much larger black hole for example.) tear a black hole apart, or would it be held together by so much force that nothing could?

Can the distance between a pair of binary planets be close enough that the gasses making up their atmospheres could mix at the L1 Lagrange point, without either planet being pulled apart by their partner planet's gravitational field?

How widespread would the damage be, if any. Would it cause the exctinsion of homo sapiens? In theory the Moon would turn into a visible ring around earth, would a new moon be created from the remaining matter, and how would this new moon affect earth.

I am in college studying physics, and someone here recently asked if the moons of Auraxis should work the way they do. I attempted to figure it out.

What you are looking for is called a Roche limit, and it is where tidal force rips a planet apart. For large bodies like planets and stars, you can generally assume very little to no surface tension because the strength of rocks is much less than the strength of the gravity they are held in place by, so it only takes a small difference in gravity to pull a planet apart. For example, the moon is pretty small, but it causes the tides to rise almost 15 meters in some places from almost a quarter million miles away.

I just ran the calculations for it, and it looks like while the earthlike planet is perfectly safe, the europalike moon is in danger, and the jupiterlike moon is only about twice the distance of the Roche limit, so there would be a considerable difference in gravity from one side to the other. I can only assume Auraxium is holding the moon together!

Edit: here is my work. https://imgur.com/gallery/nszuI

All numbers were gathered either by guessing gun dimensions in game or consulting wikipedia. I hope you like it!

/u/Dzugavili spurred me on to look into this from his comment here: https://www.reddit.com/r/CreationEvolution/comments/adj75j/invitation_to_dialogue_cybertruth5/ednofgh/

Here's what I've found

• The earth moon distance is 384,400 km.
• The Roche limit is 18,470 km. (Some sites say that it's 9496 km, but they are the exception).
• Thus the distance from the present position of the moon to the roche limit is A-B = 365,930 km.
• The moon is receding at 3.82 cm/year. Some sites claim 4.4cm/year.

Using v = d/t we get t = 365,930,000 m / 0.0382m/year = 9.5 billion years.

This means that the moon cannot be more than 9.5 billion years old (and the solar system is supposed to be 4.5 billion years old). So this doesn't pose any sort of problem for an evolutionary model.

If we use the faster recession rate, we get 8.3 billion years as the max age of the moon. Still no problem.

##However

However, this assumes that the recession rate is constant.

I'm trying to find out more about this and am not having much success. Some sites say that the recession rate would have been less in the past, others say that it would have been greater - as the moon moves away the tidal bulge angle decreases so there is less effect. This latter view makes sense to me.

Other findings:

• Answers in Genesis calculates the recession rate of the moon as k/r^6 I don't know where this comes from. (also here ). This gives a maximum age of about 1.5 billion years.
• The current recession rate is high enough to cause some consternation. The solution is to claim that it is, at present, anomalously high.
• This paper (Earth and Planetary Science, 2017) agrees with the AIG calculations (wow!!) and comes up with another way to show that the recession rate was much lower in the past. --->

>Dissipation of tidal energy causes the Moon to recede from the Earth. The currently measured rate of recession implies that the age of the Lunar orbit is 1500 My old, but the Moon is KNOWN to be 4500 My old. (emphais added) Consequently, it has been proposed that tidal energy dissipation was weaker in the Earth's past, but explicit numerical calculations are missing for such lon

Two weeks ago a question came up regarding a pair of tight-orbit binary moons, and whether or not the arrangement was even possible. Having gotten back to The Bubble from an exploration expedition earlier than I expected, I visited the system in question, AUCOKS NX-M B10-0, to get the actual stats for the two moons, AUCOKS NX-M B10-0 1 D and AUCOKS NX-M B10-0 1 E.

The two moons turn out to be 2,930km apart (1,469km, surface-to-surface), and the fluid Roche limit for the pair calculates to 1,864.77km, meaning that the pair would have to be at least 1,065km closer together before they start tearing one-another apart.

The real Roche limit for these binaries would probably be even tighter, closer to 1,400km, as the calculations for a fluid body assumes that they're just a loose pile of debris, whereas the actual moons will be more rigid than that.

AUCOKS NX-M B10-0 1 D:

• Earth Masses: 0.0013 (7.7688E+21kg)
• Radius: 760km
• Volume: 1.84E+9
• Density: 4.22g/cm3

AUCOKS NX-M B10-0 1 E:

• Earth Masses: 0.0010 (5.976E+21kg)
• Radius: 701km
• Volume: 1.44E+9
• Density: 4.15g/cm3

are we at the end of the line? has your affection for me waned? you dont talk the same as before. you dont look at me as before. you speak the words, but I don't feel them as before. its ok to feel this way. but, please let me know. set me free. sometimes we drift away. and thats ok, but if its true, let me go. I love you, L.