You are an insanely good source of info. I'm writing a fantasy novel where the planet has two close moons and I rewatched this video simply to make sure they I had a good idea of how close they could be. It's fantasy so accuracy isn't exactly absolutely needed, but it provides some good guidelines to make it believable.
I couldn't help but smile at that. I heard "Halo ring" and thought, 'surely he's not?'. Fraser has been one of my favorite people one RUclips for a long time, but he just won even more points for that one :D
How about neutrinos? What kind of particles are they? How are they generated by stars and in catastrophic events like supernovas? How do we detect them? What role do they play in the formation of neutron stars? (Might be a bit much for a single episode though...)
Hey Fraser, quick question. I know you guys have been using this video format for a while now, but I don't understand why you don't use an introduction in the video. At no point in the video do you identify yourself or Universe Today, and you don't buffer the beginning of episodes with anything. Just curious - thanks again for a great video
It's a personal preference. If you look at the older ones, I do introduce myself, but I found it was just extra time wasted. I personally prefer when people just get right into it. I've got a lower-third that shows up early on. We're going to experiment with doing a cold open, where we do something for a few seconds and then cut to a standard intro montage.
I love using these fascinating discoveries and their intricate detail to show off how awesome science is. However, I've sometimes been caught red handed mistaking hypothesis for mathematically established facts. Query: are details on your channel such as the duration of the ancient Earth day confirmed, or theorized? Love your channel. I get inspiration for more of my sci fi writing every episode!
I'm very careful to have sources when I mention specific numbers. I'm going to figure out a way to actually link them up within the video so you can go down the rabbithole if you like.
Your title just made me imagine an awesome sci-fi movie scene in which a moon is rolling around on the surface of another planet leaving a chasm of upheaval behind it
Great video! I'm still newly subscribed, but I've been really enjoying your videos! I've binge watched all of them already, I hope there'll be more soon! :)
I was hoping for a calculation of Earth-Moon system Roche limit. The Wikipedia page is either wrong, the table of data is wrong, or written really badly (using units different to those shown in the tables), because if you use the data on the page and the first formula for Roche limit on the page, what you get is NOT THE SAME as the Roche limit they've specified for Earth-Moon.
This contradiction always made me laugh at Uni.. So the theory of the creation of the moon is that a Mars sized celestial body collided with earth.. then "ignored the Roche limit" and slowly pulled away form earth? I guess the defence was.. after the collision it was further away than 9k km. Apart from that, great video!
Is there somewhere that covers the mathematics for the rotation VS orbit rates? They both rotate but there is only one orbital period. How is the hierarchy determined, size/shape or mass? ...or maybe they both move in relation to the axis of orbit(center of mass for the system) depending on one's own spin, making it seem like the other is moving. Perhaps this is simply another counter intuitive thing with orbital mechanics.
Can you be more specific? The initial rotation just comes from the total momentum of all the particles that came together to create the planet in the first place. Orbital speeds depend on distance and mass of the objects involved.
Whilst on the topic of the orbital characteristics of the moon. How is it that the moon ended up in a nearly circular orbit without an 'orbital insertion burn'? It seems that after a collision, all the debris kicked up would fall back to earth on account of cause the perihelion of the orbits of all that stuff 'should' have intersected with the earth's surface, which I imagine wouldn't be too good for making moons.?
History is very interesting, but unfortunately I am unemployed, but I probably would be if I was an "de facto" astronomer too. Portugal is going through a very nasty economic crisis...
+alternatehistorypt im sorry to hear that, im very interested in history and think that is fills in important role in society that barely is recognized, therefore im questioning if it would be viable to study it. but since you already have, i hope for the best for you, hang in tjere and times will get better!
@alternatehistorypt - man, that sucks. can you relocate? One of the biggest points of knowing and studying history is the ability to share it so that we don't continue to make the same mistakes... I hope you find work soon. @gruffgruff92 *im questioning if it would be viable to study it* I cant speak for anyone else but i can pass on this important piece of advice i learned in my youth: always do (work, study, learn etc) at something you love and are passionate about, regardless of the topic. it will never be a "job" and you will never work a day in your life.
Hey Fraser cool channel. There are a lot of people saying Nibru is here and can be seen almost like the moon, or it's on the other side of the sun. Am I wrong or would this not cause some kind of affect on the earth and even the orbits of the other planets?
This is an awesome video. The bit about angular momentum: I attempted to do some maths. Is the total angular momentum of the earth-moon system equal to l1 (angular momentum due to moon's rotation) + l2(angular momentum due to earth's rotation) + L3(angular momentum due to moon's orbit)? This quantity is then conserved. l1 = (angular velocity) * radius of moon; l2 = (angular velocity) * (radius of earth); L3 = (orbital velocity) * (earth-moon distance). Then the 2 angular velocities decrease, so (earth-moon distance) must increase. Am I right? The reason why (orbital velocity) cannot increase: is it because WORK would need to be performed by an external force (force * distance) so the moon would need to gain energy. This would violate conservation of energy. Am I right on that? I hope what I wrote makes sense.
Hey Fraser, you are awesome! I have a question. Is the moon 100% tidally locked to Earth or it just happens that it rotates at the same time it orbits Earth? Will someday (long after us) the moon rotation will become so slow that, form Earth, it will seem to spin again? And if it does, will it look like it spins backward, viewed from Earth? Like you said, it was spinning faster long ago, then it slowed down due to tidal forces, until it takes the same time for it to make one spin than to make one orbit. So if it is not 100% tidally locked, I believe it will continue to slow down until it takes months to make one spin. And then, on Earth "we" (life, maybe humans...) will see it spin anti clockwise.
Would we expect to see some systems where the planet sped up enough to get into equilibrium? If a moon going lagging behind a planet causes the planet rotation to speed up, they could meet in the middle if its not too extreme right? Similarly could this happen to the Moon eventually or would it escape Earth's gravity by the time it reaches a distance at which Earth would be slow enough to keep the Moon?
Pluto and Charon are in equalibrium. They are mutually tidally locked. Each shows just one side to the other. I think that means Pluto and Charon don't drift apart or together since tides can't transfer their angular momentum. Makes me sad to see Pluto not included as a planet anymore. Pluto and Charon, two spherical bodies, mutually locked. Only because they cross Neptune's orbit Pluto loses planet status.
Oh yeaaah nice thinking; I hadn't connected those dots. Knew there were some examples of mutual tidal locking, including Pluto/Charon. Astronomers seem to be accepting Pluto's demotion, but from what I understand the committee which originally decided had very very low attendance during that vote. As such I just flatly ignore it. Our definition is wonky. Imagine an intergalactic ship coming across a rouge body the size of Earth that was slung out of the galaxy. They're gonna call that a planet. If you absolutely care about the dominant gravity of the object, I think what really matters is that the Pluto/Charon gravity well is dominated by the Sun rather than Neptune. For instance if the moon were floating around the asteroid belt, I'd consider that a planet. Eh opinions on youtube, whatcha gonna do I don't mind classifying it as a dwarf planet, but that's still.. a planet. Just like Jupiter is a gas giant. IMO anything with enough gravity to become a sphere and too little to be a star, is a planet unless it is very clearly a satellite.
Possibly. But it could have been a very icy moon of Saturn that passed the Roche Limit then creating a couple of rings around Saturn. There are other theories though.
Mind blown. Would be fascinating to watch a comet get shattered by whizzing past a (not ours) planet... 🤔 In that case gravity must be like a shell around a planet right? Does the destruction happen immediately? Or is it a slow crumbling process? 🤔
If a moon crosses the roche limit how quickly does it break up? Are we talking gradually over a long period of time, or does it just rapidly disintegrate as if shot by a death star?
It'd still take millions of years for the ring to disappear, which is what is supposed to happen to Saturn's rings. Not like the ring would immediately bombard Earth right away.
Has Fraser Cain done a video about schwarzchild radii? Maybe Bose Einstein condensate. Or maybe black body radiation. It's kinda a simple topic but it plagued me trying to find a clear cut understandable answer.
Depends on rigidity of the meteorite. Roche limit only applies to highly fluid satellite such as comet. Most meteorite are rigid with high iron content so unfortunately its rigidity will survive Roche's limit and crash onto earth surface
Fraser, you said you were looking for idea episodes. Here's one. Using Newton's Law of Gravity, it can be easily seen that the Sun has about TWICE the gravitational attraction on the Moon as Earth does. Since gravitational "ownership" determines whether something is a planet or a moon, it would seem that the Moon is actually a planet. And, if that is the case, one would expect the Moon to orbit the Sun rather than the Earth. Are the Earth and the Moon doing a complex "dance" around one another so that both of their orbits are always concave relative to the Sun???
FWIW, I didn't come up with the idea myself, Fraser. I first came across it in a science book written by Isaac Asimov. I think Isaac was actually a better science writer than SciFi writer!
" the Roche Limit between the Earth and the Moon is about 9,500 kilometers" "If an average comet got within about 18,000 km of Earth, it would get torn to pieces. While the Sun can, and does, tear apart comets from about 1.3 million km away" Why for the moon the Roche limit is 9,500 km and for other rooks is 18,000 km? Wouldn't it be the same or we are not considering the moon the same density with the comet? Taking in to account that the moon is a Rock under my calculations it came that the Roche limit would be around 19,000 km
How much force would be needed to stabilize the Moon's orbit to no longer be receding away from the Earth. What would be the effect on the Earth is someone / something did this ? also, what would be the force necessary to alter the Moon's orbit into a North to South polar orbit and what would the effects of this be ?
1. i don't think it's possible. our geostationary orbit is 36000 km above earth and fraser said it would be torn apart at 95000 km. 2. that's a wrong question, you should be rather asking how much energy you would need for that you need to look Moon's mass and velocity. you need some kinetic energy to stop it( 1/2m*v^2 )and then you also need the same amount to accelerate it on another orbit.
2. putting the Moon into a polar orbit would take a lot, shit tonne, h*ly flip of a lot of energy. The Moon may not look very big from here but it's still huge. The effect: I'd bet it would harshly change Earth's axis of rotation. The tidal bulge, going polar instead of roughly equitorial, makes a powerful mechanism for transferring angular momentum. On a sad note, a polar orbiting Moon would almost eliminate solar and lunar eclipses. They would only be possible twice a year instead of nearly monthly.
You said that when a moon passes the Rouche limit, it gets torn apart and forms a ring around its planet. Then the debris that forms the ring crashes into the planet. So my question is, will Saturn's rings disappear in the distant future, or are they a permanent feature? I thought I heard somewhere that there is something that replenishes them, but I'm not sure. Anyway, that might make an interesting episode.
I thought I had read that Saturn's rings were a 'recent' fixture, only a few tens of millions or hundreds of millions years old. I went hunting for references and only turned up "Rings 4.4 billion years old says Cassini mission". But those headlines were at least four years old and I'm pretty sure I heard the young-rings theory less than a year ago.
The rings will eventually be consumed by the celestial body, however, in this generation we will obviously not be able to gaze upon this event. Vsauce did a video called "What Will We Miss?" or along the lines of that.
I read about Niku. Not quite retrograde but something like 117 degrees off the ecliptic. Makes you wonder where the line is for declaring something is of interstellar origin and what was part of the primordial solar system.
Sounds like this would be a great way to mine an asteroid - move it into orbit of earth, move it inside the roche limit, let it break up and then grab the pieces we want. Would that work, or would we have to get it dangerously close first?
"insignificant compared to the chemical bonds holding you together..." I don't get it. The moon is held together purely by gravity? There are no chemical bonds between the matter making up the moon?
Can you explain what it means when astronomers say that the universe has no shape or end. If I were immortal and travelled faster than the speed of the universe's expansion, would I reach an end?
I remember my astronomy professor saying that it just wouldnt make any sense for space to have a limit. Because then there would have to be something else outside that and outside that and outside that. So its probably infinite or closed, meaning that gravity warps space around itself so if you travel far enough you would just end up in the same place.
+Josh g I thought it was generally understood that you could travel in space in a straight line forever in the same sense that you can walk the surface of a sphere without encountering an edge. How could we test this? What if we set up a big-ass LHC out in space and blast some protons out in an arbitrary direction then wait a while for them to come up behind us. The LHC can get protons up to pretty close to the speed of light...
+Josh g Yeah. It just dawned on me that my LHC in space wouldn't work since from an observers (our) point of view the protons would take many billions of years to circumnavigate the universe. The protons might only experience years or centuries in subjective time but that doesn't help the observer... And all of that presumes a closed geometry for the universe. So, as you say, we may have to chalk up the geometry of the universe as unknowable.
I'm a believer, I do have a question if gravity can't literally be proven how is it proven that the Moons gravity slows down Earth? Is this something that can be explained in layman's terms? 🙃🙂 Appreciate cha!🌍💚🌾🎼❤️✨🍄🧘🏻♀️
I don't understand why the rate of rotation of the earth has anything to do with the gravitational pull on the moon. why didn't the moon crash into the earth when it was much closer... this isn't fully explained
Because it was orbiting faster than a single day on Earth. That means that it slows down the rotation rate of the Earth and drifts away to compensate. If it orbited faster than a single day on Earth, then it would speed up the Earth's rotation and drift inward.
Gravity is a distortion of space by mass. Objects think they're following a straight path, when they're actually following the path created by another massive object.
I saw in another scientist video that the moon is actually falling around earth or something like that. If the moon is so far away how can it's weak gravity affect the ocean tides of earth or anything for a matter of fact. It just doesn't make sense to me
+Chunky Rivera Orbits, including the Moon's are all about falling... but constantly missing. The nonintuitive thing about large body orbits is that the parent body is also orbiting the smaller one. The Earth and Moon are actually moving around their mutual barycenter, their center of mass. Tides come from the fact that the Earth is not a point mass. Part of the Earth is closer to the Moon than other parts. According to Newton's equation for gravitation gravity varies with the square of the distance between the masses. Masses twice as far apart experience one quarter the gravity. Earth's nearer side to the Moon is 12,742km closer than the far side so experience slightly more gravity. Thus the nearer side falls a little faster toward the Moon than the far side, pulling the Earth slightly along the axis pointed toward the Moon. You get to see this on coastlines as water stretches much more than the rocky coast. You don't personally feel the Moon's tide because your day-to-day experience is dominated by Earth's gravity. Apollo astronauts didn't fall off the Moon during their brief stay because their experience was dominated by the Moon's gravity.
Assuming we don't selt-extinct soon then I'm betting we won't survive the universe. We are embedded in the universe. So far we have no evidence for stuff that isn't part of the universe. There are theories for multiple universes but no way to test for them... yet. If the universe dies in a big rip (dark energy rips atoms apart) we don't have somewhere else to go to keep our atoms safe. If heat death is the way it goes humanity will have no way to get energy to 'keep the lights on', in every sense of the phrase. A big crunch? Still no other place to go to escape it. So even if humanity manages to not go extinct, by going interstellar for instance, the universe's end means that the whole enterprise is pointless. But that doesn't mean we can't have a lot if fun for the next googol years.
+Fraser Cain True, but humanity is going to be the sole exception :). The naive argument: Homo Sapien has been a thing for about 200,000 years. Studies suggest mammalian species last around 1 million years so we aught to get another 800,000 years. Humanities technology is completely unprecidented on Earth. From Watson&Crick 1953 to present CRISPR we have seized the reigns on our evolution from nature. We are at most 10 years from eliminating genetic disorders like Huntington's and cystic fibrosis. Famines don't need to effect us anymore... much to the detriment of waistlines in the Western World. And unlike the dinosaurs we have a space program. But, yeah, we may be too smart for our own good. CRISPR might save us or give jihadis everywhere a tool to engineer a zombie apocalypse. The space program is neato but a toupeed pumpkin can press a button to deliver an atomic bomb half-way around the world.
Lots of small stuff in space has the strength of dust bunnies. Comet 67P (whose Russian name I am not worthy to spell) has the consistency of a big pile of packing peanuts. Rocks of the caveman variety need a bit of cooking to melt together. And if you've spent time on a prison chain gang you'd know rocks are way tougher than dust bunnies or packing peanuts.
![I.N "HALLUCINATION" | [Stray Kids : SKZ-PLAYER]](http://i.ytimg.com/vi/n5B5q1Hwt_U/mqdefault.jpg)
You are an insanely good source of info. I'm writing a fantasy novel where the planet has two close moons and I rewatched this video simply to make sure they I had a good idea of how close they could be. It's fantasy so accuracy isn't exactly absolutely needed, but it provides some good guidelines to make it believable.
Subscribed :) This was an awesome explanation
Thanks a lot! Welcome aboard.
Hello Tibees.
Anyone else here because of Kirby?
yes
*yes*
Yup
Guilty
Yup
Hooray, Halo reference!
I couldn't help but smile at that. I heard "Halo ring" and thought, 'surely he's not?'. Fraser has been one of my favorite people one RUclips for a long time, but he just won even more points for that one :D
yay!
I'm glad someone got that. :-)
+Fraser Cain Yay, he responded! That's the second ever time a big RUclipsr has responded to my comment on their video!
Hell yeah!! Cool factor dialed to 11 on this one!
This channel is amazing
Who knew 4 years later I would find this channel because of my love if space
Welcome aboard. Don't forget to subscribe. :-)
ironically all those pieces of halo crashing on our seas will only increase the presence of the ''floods''.
do you get the reference
Jake Wolfram yes, yes I do.
I love your videos! You definitely deserve more subscribers.
Thanks a lot, nag your friends to subscribe. :-)
Hey Fraser, thanks for answering my question about the Roche limit in this episode!
It was a lot of fun. Keep those questions coming.
How about neutrinos?
What kind of particles are they? How are they generated by stars and in catastrophic events like supernovas? How do we detect them? What role do they play in the formation of neutron stars?
(Might be a bit much for a single episode though...)
Master Chief FTW! Nice Halo / Flood reference; +1
Hey Fraser, quick question. I know you guys have been using this video format for a while now, but I don't understand why you don't use an introduction in the video. At no point in the video do you identify yourself or Universe Today, and you don't buffer the beginning of episodes with anything. Just curious - thanks again for a great video
It's a personal preference. If you look at the older ones, I do introduce myself, but I found it was just extra time wasted. I personally prefer when people just get right into it. I've got a lower-third that shows up early on.
We're going to experiment with doing a cold open, where we do something for a few seconds and then cut to a standard intro montage.
That Halo reference was TOP QUALITY
I love using these fascinating discoveries and their intricate detail to show off how awesome science is. However, I've sometimes been caught red handed mistaking hypothesis for mathematically established facts. Query: are details on your channel such as the duration of the ancient Earth day confirmed, or theorized?
Love your channel. I get inspiration for more of my sci fi writing every episode!
I'm very careful to have sources when I mention specific numbers. I'm going to figure out a way to actually link them up within the video so you can go down the rabbithole if you like.
Your title just made me imagine an awesome sci-fi movie scene in which a moon is rolling around on the surface of another planet leaving a chasm of upheaval behind it
That's too low!
Perhaps an episode on the Moon's characteristic mare on it's Earth facing hemisphere or a video on the geological activity of moons in general?
I like that idea, can moons have earthquakes? Or just talk about "seismic" activity on other worlds in general.
Awesome! Looking forward to the next video too.
Thanks, it's a fun one. :-)
Nice tie in to the moon is a harsh mistress.
also seveneves
That was totally accidental. We were shooting, and Chad mentioned that I should have included Seveneves... d'oh!
Fraser Cain talking about the moon cracking, falling and forming a ring is essentially seveneves. #AccidentalReference ^_^
Great video! I'm still newly subscribed, but I've been really enjoying your videos! I've binge watched all of them already, I hope there'll be more soon! :)
Thanks for it!
more black hole stuff next? oh i love it i could watch this stuff all day
awesumm as usual
Yes, the Halo reference. I knew my subscription would pay off, eventually. Thanks, Chief.
Question: how long will it take for the moon to escape Earth's gravity well completely?
That was even more informative than when I googled it, Thanks!
We talk about it in this video: ruclips.net/video/qMTRiql9fvM/видео.html
I was hoping for a calculation of Earth-Moon system Roche limit. The Wikipedia page is either wrong, the table of data is wrong, or written really badly (using units different to those shown in the tables), because if you use the data on the page and the first formula for Roche limit on the page, what you get is NOT THE SAME as the Roche limit they've specified for Earth-Moon.
Here's an article from McGill University that goes into it, as well as the equations: www.cs.mcgill.ca/~rwest/wikispeedia/wpcd/wp/r/Roche_limit.htm
Darian Christie I just watched a video that said it was 18,000km
This contradiction always made me laugh at Uni.. So the theory of the creation of the moon is that a Mars sized celestial body collided with earth.. then "ignored the Roche limit" and slowly pulled away form earth? I guess the defence was.. after the collision it was further away than 9k km. Apart from that, great video!
Awesome video as always :) I have a question: why our ring of broken Moon would fall toward us and the Saturn's rings wouldn't do it?
Is there somewhere that covers the mathematics for the rotation VS orbit rates? They both rotate but there is only one orbital period. How is the hierarchy determined, size/shape or mass? ...or maybe they both move in relation to the axis of orbit(center of mass for the system) depending on one's own spin, making it seem like the other is moving. Perhaps this is simply another counter intuitive thing with orbital mechanics.
Can you be more specific? The initial rotation just comes from the total momentum of all the particles that came together to create the planet in the first place. Orbital speeds depend on distance and mass of the objects involved.
Hi Fraser, can you do a video on primordial black holes, and/or branes? Cheers.
The roche limit depends mainly on two things, the size and mass of the planet, and the size and mass of the moon.
Whilst on the topic of the orbital characteristics of the moon. How is it that the moon ended up in a nearly circular orbit without an 'orbital insertion burn'? It seems that after a collision, all the debris kicked up would fall back to earth on account of cause the perihelion of the orbits of all that stuff 'should' have intersected with the earth's surface, which I imagine wouldn't be too good for making moons.?
What's the Roache Limit between Arnold Schwarzenegger and Danny Devito?
I really can't think of a whitty response yet. I'll get another cup of coffee and see if I can do better.
I'd say smaller than the average filesize of an experiment on a hard disk.
It has been a whole year and no witty response yet?
What would it be like living on a planet as it approaches the Roche limit?
I dunno, but the final boss theme from Kirby and the Forgotten Land would probably be playing in everyone's heads.
I guess it depends on which planet has the gravitational force will depend on if you’re lucky or unlucky
awesome video, I have a degree in History but I am still an amateur astronomist :)
how is that working out? would it be worth it to study history?
History is very interesting, but unfortunately I am unemployed, but I probably would be if I was an "de facto" astronomer too. Portugal is going through a very nasty economic crisis...
+alternatehistorypt im sorry to hear that, im very interested in history and think that is fills in important role in society that barely is recognized, therefore im questioning if it would be viable to study it. but since you already have, i hope for the best for you, hang in tjere and times will get better!
@alternatehistorypt - man, that sucks. can you relocate?
One of the biggest points of knowing and studying history is the ability to share it so that we don't continue to make the same mistakes...
I hope you find work soon.
@gruffgruff92 *im questioning if it would be viable to study it*
I cant speak for anyone else but i can pass on this important piece of advice i learned in my youth: always do (work, study, learn etc) at something you love and are passionate about, regardless of the topic. it will never be a "job" and you will never work a day in your life.
I hope so, and if you are interested in History you can visit my channel perhaps :)
Hey Fraser cool channel. There are a lot of people saying Nibru is here and can be seen almost like the moon, or it's on the other side of the sun. Am I wrong or would this not cause some kind of affect on the earth and even the orbits of the other planets?
There's no such thing as Nibiru, it's a myth. Those people are literally making things up.
This is an awesome video. The bit about angular momentum: I attempted to do some maths. Is the total angular momentum of the earth-moon system equal to l1 (angular momentum due to moon's rotation) + l2(angular momentum due to earth's rotation) + L3(angular momentum due to moon's orbit)? This quantity is then conserved. l1 = (angular velocity) * radius of moon; l2 = (angular velocity) * (radius of earth); L3 = (orbital velocity) * (earth-moon distance). Then the 2 angular velocities decrease, so (earth-moon distance) must increase. Am I right?
The reason why (orbital velocity) cannot increase: is it because WORK would need to be performed by an external force (force * distance) so the moon would need to gain energy. This would violate conservation of energy. Am I right on that?
I hope what I wrote makes sense.
gonna cover the proton radius puzzle?
Wow, this is super interesting, especially the recent results. I'll dig into it.
Talk about Neptune’s moon triton and what is future holds
Hey Fraser, you are awesome! I have a question. Is the moon 100% tidally locked to Earth or it just happens that it rotates at the same time it orbits Earth? Will someday (long after us) the moon rotation will become so slow that, form Earth, it will seem to spin again? And if it does, will it look like it spins backward, viewed from Earth?
Like you said, it was spinning faster long ago, then it slowed down due to tidal forces, until it takes the same time for it to make one spin than to make one orbit. So if it is not 100% tidally locked, I believe it will continue to slow down until it takes months to make one spin. And then, on Earth "we" (life, maybe humans...) will see it spin anti clockwise.
Here's a video for you: ruclips.net/video/VGnIuqYKnTE/видео.html
Short answer, it rotates once for every orbit.
Can you explain why the Mars-sized planet were not torn into part when reach Roche limit, but collided with the Earth?
It probably was torn apart and then it all crashed into the Earth.
What does a star would look like from the moment it starts fusion to the moment it's all "ignited"?
It.. would like a normal star..
Would we expect to see some systems where the planet sped up enough to get into equilibrium? If a moon going lagging behind a planet causes the planet rotation to speed up, they could meet in the middle if its not too extreme right?
Similarly could this happen to the Moon eventually or would it escape Earth's gravity by the time it reaches a distance at which Earth would be slow enough to keep the Moon?
Pluto and Charon are in equalibrium. They are mutually tidally locked. Each shows just one side to the other. I think that means Pluto and Charon don't drift apart or together since tides can't transfer their angular momentum.
Makes me sad to see Pluto not included as a planet anymore. Pluto and Charon, two spherical bodies, mutually locked. Only because they cross Neptune's orbit Pluto loses planet status.
Oh yeaaah nice thinking; I hadn't connected those dots. Knew there were some examples of mutual tidal locking, including Pluto/Charon.
Astronomers seem to be accepting Pluto's demotion, but from what I understand the committee which originally decided had very very low attendance during that vote. As such I just flatly ignore it.
Our definition is wonky. Imagine an intergalactic ship coming across a rouge body the size of Earth that was slung out of the galaxy. They're gonna call that a planet. If you absolutely care about the dominant gravity of the object, I think what really matters is that the Pluto/Charon gravity well is dominated by the Sun rather than Neptune. For instance if the moon were floating around the asteroid belt, I'd consider that a planet. Eh opinions on youtube, whatcha gonna do
I don't mind classifying it as a dwarf planet, but that's still.. a planet. Just like Jupiter is a gas giant. IMO anything with enough gravity to become a sphere and too little to be a star, is a planet unless it is very clearly a satellite.
Were Saturn's ring caused by the Roach limit of a few moons breaking them apart?
yes. exactly.
Possibly. But it could have been a very icy moon of Saturn that passed the Roche Limit then creating a couple of rings around Saturn. There are other theories though.
AND HERE WE ARE
Cool. What's the Roche Limit between Venus and Earth or Jupiter and Earth?
Here's a page that gives you the Roche Limit calculations for any two objects.
Link?
How do you build a cold weather machine?
Wow, that would be great. :-)
I'd do a space parasol. But just to safe I'd try it out on Venus first.
Mind blown.
Would be fascinating to watch a comet get shattered by whizzing past a (not ours) planet... 🤔
In that case gravity must be like a shell around a planet right? Does the destruction happen immediately? Or is it a slow crumbling process? 🤔
If a comet gets close enough, it'll get torn apart in a few hours by the tidal forces.
You should do a video on quantum entanglement.
That's on my list. :-)
If a moon crosses the roche limit how quickly does it break up? Are we talking gradually over a long period of time, or does it just rapidly disintegrate as if shot by a death star?
It'd still take millions of years for the ring to disappear, which is what is supposed to happen to Saturn's rings. Not like the ring would immediately bombard Earth right away.
Scientists still aren't sure how old Saturn's rings are, and long they're going to last.
It takes a measly earth’s gravity to rip the moon apart, but a blackhole to rip us apart. Humans are bad ass.
Nice!
What is the roche limit between the earth and mars?
i have a question: How did the earth get its tilt of 23.5 degrees and would life have evolved differently if it didn't have the tilt.
The same kind of early Solar System madness that flipped Uranus on its side.
I think the impact that made the moon caused it, and the moon's gravity is preventing the axis to shake.But yea, without tilt, there wont be seasons.
Has Fraser Cain done a video about schwarzchild radii? Maybe Bose Einstein condensate. Or maybe black body radiation. It's kinda a simple topic but it plagued me trying to find a clear cut understandable answer.
Great suggestions, thanks!
So then if a metiroid comes close to earth, can rouche limit can destroy that metiroid.(assuming that metiroid aim is to hit the earth)
Depends on rigidity of the meteorite. Roche limit only applies to highly fluid satellite such as comet. Most meteorite are rigid with high iron content so unfortunately its rigidity will survive Roche's limit and crash onto earth surface
Does that mean we're safe from certain loosely held together asteroids as long as the chunks aren't too big?
A loose collection of rocks would be less dangerous than a single metal asteroid, but still dangerous.
hey nice Halo reference!
About 1% of the viewers will get that, everyone else will think I had a stroke.
Fraser, you said you were looking for idea episodes. Here's one. Using Newton's Law of Gravity, it can be easily seen that the Sun has about TWICE the gravitational attraction on the Moon as Earth does. Since gravitational "ownership" determines whether something is a planet or a moon, it would seem that the Moon is actually a planet. And, if that is the case, one would expect the Moon to orbit the Sun rather than the Earth. Are the Earth and the Moon doing a complex "dance" around one another so that both of their orbits are always concave relative to the Sun???
I like that. "Shouldn't the Moon Be a Planet?"
FWIW, I didn't come up with the idea myself, Fraser. I first came across it in a science book written by Isaac Asimov. I think Isaac was actually a better science writer than SciFi writer!
How do The Flood factor into that analogy? It was already quite the stretch.
I used the words Halo and ring, and my brain just went there. I should have made a Seveneves reference instead, but I haven't ready it yet. :-(
touché
awesome
People in 65 billion yeasrs: *"That is no moon!* It's a ring"
" the Roche Limit between the Earth and the Moon is about 9,500 kilometers"
"If an average comet got within about 18,000 km of Earth, it would get torn to pieces. While the Sun can, and does, tear apart comets from about 1.3 million km away"
Why for the moon the Roche limit is 9,500 km and for other rooks is 18,000 km? Wouldn't it be the same or we are not considering the moon the same density with the comet?
Taking in to account that the moon is a Rock under my calculations it came that the Roche limit would be around 19,000 km
How much force would be needed to stabilize the Moon's orbit to no longer be receding away from the Earth.
What would be the effect on the Earth is someone / something did this ?
also, what would be the force necessary to alter the Moon's orbit into a North to South polar orbit and what would the effects of this be ?
1. i don't think it's possible. our geostationary orbit is 36000 km above earth and fraser said it would be torn apart at 95000 km.
2. that's a wrong question, you should be rather asking how much energy you would need for that
you need to look Moon's mass and velocity.
you need some kinetic energy to stop it( 1/2m*v^2 )and then you also need the same amount to accelerate it on another orbit.
You would need to change the Earth's rotation period so that it matches the Moon's orbit. Are you ready for month-long days?
2. putting the Moon into a polar orbit would take a lot, shit tonne, h*ly flip of a lot of energy. The Moon may not look very big from here but it's still huge. The effect: I'd bet it would harshly change Earth's axis of rotation. The tidal bulge, going polar instead of roughly equitorial, makes a powerful mechanism for transferring angular momentum.
On a sad note, a polar orbiting Moon would almost eliminate solar and lunar eclipses. They would only be possible twice a year instead of nearly monthly.
You said that when a moon passes the Rouche limit, it gets torn apart and forms a ring around its planet. Then the debris that forms the ring crashes into the planet. So my question is, will Saturn's rings disappear in the distant future, or are they a permanent feature? I thought I heard somewhere that there is something that replenishes them, but I'm not sure. Anyway, that might make an interesting episode.
I thought I had read that Saturn's rings were a 'recent' fixture, only a few tens of millions or hundreds of millions years old. I went hunting for references and only turned up "Rings 4.4 billion years old says Cassini mission". But those headlines were at least four years old and I'm pretty sure I heard the young-rings theory less than a year ago.
The rings will eventually be consumed by the celestial body, however, in this generation we will obviously not be able to gaze upon this event. Vsauce did a video called "What Will We Miss?" or along the lines of that.
Do an episode on "Niku" the object that orbits the sun backwards!
Wow, this thing is newly discovered. I'll need to talk to Mike Brown and Konstantin Batygin again. :-)
I read about Niku. Not quite retrograde but something like 117 degrees off the ecliptic. Makes you wonder where the line is for declaring something is of interstellar origin and what was part of the primordial solar system.
Might this explain Saturn's rings?
Saturn's gravity keeps the ring material churned up so it can't form into moons.
Sounds like this would be a great way to mine an asteroid - move it into orbit of earth, move it inside the roche limit, let it break up and then grab the pieces we want. Would that work, or would we have to get it dangerously close first?
Just be really really careful. You'd need to get that asteroid very close to Earth.
Perhaps we should use the moon instead, then...
@@Werrf1 yea, the Moon have its roche limit too, smaller tho
I love you FrAISER Cain 😂😂😂
Prompter remote clicking is audible.
What are you clicking in your hand?
That halo reference made me like you more
Trippy
What!?!?! The moon is getting closer to us???? We need to do something about that!
No, the Moon is drifting away from us.
have you done an episode talking about the so called hallow moon or hallow earth whether there is any so called proof of what people claim?
So in about the year 1800 how close was the moon to earth then compared to now I'm no good with math someone please help me out
8.8 meters closer to earth.
Now replace the moon with a planet...
And here we are!
How close 2 Earth-sized planets could orbit each other in their double planetary system?
Within their mutual roche limits. If you get too close, you'll get a contact binary: a peanut shaped world. :-)
That halo pun tho
Glad you got it. ;-)
"insignificant compared to the chemical bonds holding you together..."
I don't get it. The moon is held together purely by gravity? There are no chemical bonds between the matter making up the moon?
U said when moon was formed earth's rotation took only 6 hours how scientist calculate that ???
It's math. They know how fast it's slowing down now and then calculate backwards to the point that the Moon formed.
Make the Moon big again!
Just kidding.
Can you explain what it means when astronomers say that the universe has no shape or end. If I were immortal and travelled faster than the speed of the universe's expansion, would I reach an end?
no one truly knows. but probably not. just more stars that are outside our observable universe.
I remember my astronomy professor saying that it just wouldnt make any sense for space to have a limit. Because then there would have to be something else outside that and outside that and outside that. So its probably infinite or closed, meaning that gravity warps space around itself so if you travel far enough you would just end up in the same place.
+Josh g I thought it was generally understood that you could travel in space in a straight line forever in the same sense that you can walk the surface of a sphere without encountering an edge.
How could we test this? What if we set up a big-ass LHC out in space and blast some protons out in an arbitrary direction then wait a while for them to come up behind us. The LHC can get protons up to pretty close to the speed of light...
Lenard Segnitz Theres just some things we will never be able to know. The universe is expanding faster than light speed.
+Josh g Yeah. It just dawned on me that my LHC in space wouldn't work since from an observers (our) point of view the protons would take many billions of years to circumnavigate the universe. The protons might only experience years or centuries in subjective time but that doesn't help the observer... And all of that presumes a closed geometry for the universe.
So, as you say, we may have to chalk up the geometry of the universe as unknowable.
Did life existed on earth when moon was only 10,000 km away?
I'm a believer, I do have a question if gravity can't literally be proven how is it proven that the Moons gravity slows down Earth?
Is this something that can be explained in layman's terms? 🙃🙂
Appreciate cha!🌍💚🌾🎼❤️✨🍄🧘🏻♀️
I don't understand why the rate of rotation of the earth has anything to do with the gravitational pull on the moon. why didn't the moon crash into the earth when it was much closer... this isn't fully explained
Because it was orbiting faster than a single day on Earth. That means that it slows down the rotation rate of the Earth and drifts away to compensate. If it orbited faster than a single day on Earth, then it would speed up the Earth's rotation and drift inward.
how can the moon be on an elliptical orbit AND be tidally locked?
Isn't there more theories than a mars sized collision?
That's the main theory. Other theories are that it formed in place and got spun out from the early Earth, or that it was captured later on.
What would happen to the tides on Earth if there were two moons?
You would get more high and low tides. There'd be times they'd line up together with the Sun and get really high, or really low.
So, like seveneves, we'll all be dead if it gets closer!
@Fraser Cain - is Moon cheese related to ToE cheese?
Will the moon ever escape Earth?
Not before the Sun becomes a red giant.
♫ Tossed salad and scrambled eggs ♫
I'm listening.
Saw the name and, although not exact, it still invoked the song.. 😅
Could we eventually get internet on the moon?
Sure, as long as you're okay with 2 second ping times. Your Call of Duty rankings will take a hit.
Not that bad, my computer is that slow.
The moon is not leaving us.
And why do you keep saying this?
"Moon, please don't leave me (us). I'll change. We can go to binary planet counselling." : Earth probably.
Fraser Cain The moon is actually not leaving us.
I still dont' understand gravity. I get how it works but why?
Gravity is a distortion of space by mass. Objects think they're following a straight path, when they're actually following the path created by another massive object.
I saw in another scientist video that the moon is actually falling around earth or something like that. If the moon is so far away how can it's weak gravity affect the ocean tides of earth or anything for a matter of fact. It just doesn't make sense to me
+Chunky Rivera Orbits, including the Moon's are all about falling... but constantly missing. The nonintuitive thing about large body orbits is that the parent body is also orbiting the smaller one. The Earth and Moon are actually moving around their mutual barycenter, their center of mass.
Tides come from the fact that the Earth is not a point mass. Part of the Earth is closer to the Moon than other parts. According to Newton's equation for gravitation gravity varies with the square of the distance between the masses. Masses twice as far apart experience one quarter the gravity. Earth's nearer side to the Moon is 12,742km closer than the far side so experience slightly more gravity. Thus the nearer side falls a little faster toward the Moon than the far side, pulling the Earth slightly along the axis pointed toward the Moon. You get to see this on coastlines as water stretches much more than the rocky coast.
You don't personally feel the Moon's tide because your day-to-day experience is dominated by Earth's gravity. Apollo astronauts didn't fall off the Moon during their brief stay because their experience was dominated by the Moon's gravity.
Lenard Segnitz Thank you I feel I understand better now
I think we should speed up the moon 😉
Bruh why?
Could humanity survive the universe entirely?
At the rate things are going, humanity won't even be able to survive itself.
Assuming we don't selt-extinct soon then I'm betting we won't survive the universe. We are embedded in the universe. So far we have no evidence for stuff that isn't part of the universe. There are theories for multiple universes but no way to test for them... yet.
If the universe dies in a big rip (dark energy rips atoms apart) we don't have somewhere else to go to keep our atoms safe. If heat death is the way it goes humanity will have no way to get energy to 'keep the lights on', in every sense of the phrase. A big crunch? Still no other place to go to escape it.
So even if humanity manages to not go extinct, by going interstellar for instance, the universe's end means that the whole enterprise is pointless. But that doesn't mean we can't have a lot if fun for the next googol years.
Our odds aren't good. Every species eventually goes extinct.
+Fraser Cain True, but humanity is going to be the sole exception :).
The naive argument: Homo Sapien has been a thing for about 200,000 years. Studies suggest mammalian species last around 1 million years so we aught to get another 800,000 years.
Humanities technology is completely unprecidented on Earth. From Watson&Crick 1953 to present CRISPR we have seized the reigns on our evolution from nature. We are at most 10 years from eliminating genetic disorders like Huntington's and cystic fibrosis. Famines don't need to effect us anymore... much to the detriment of waistlines in the Western World. And unlike the dinosaurs we have a space program.
But, yeah, we may be too smart for our own good. CRISPR might save us or give jihadis everywhere a tool to engineer a zombie apocalypse. The space program is neato but a toupeed pumpkin can press a button to deliver an atomic bomb half-way around the world.
Fraser is one of the few men in the world that requires facial hair to be good looking
My wife won't let me shave. It's an instant divorce, apparently.
What about rocks?? They don't have chemical bonds, how are they intact on the surface of the earth.
They also are connected by chemical bonds.
Lots of small stuff in space has the strength of dust bunnies. Comet 67P (whose Russian name I am not worthy to spell) has the consistency of a big pile of packing peanuts. Rocks of the caveman variety need a bit of cooking to melt together. And if you've spent time on a prison chain gang you'd know rocks are way tougher than dust bunnies or packing peanuts.
mmmmmmm... moon cheese...