Why are so many objects in space shaped like discs? | Michelle Thaller

Why are so many objects in space shaped like discs? | Michelle Thaller

you have noticed one of the most wonderful and consistent
patterns in the whole universe. The universe is very good
at making spinning disks. Our solar system is a
disk, and all the planets go around in basically the
same plane, and they all go around in the same direction. Why should that be? There are disks all over the place. I mean, think about the rings of Saturn. The rings of Saturn are
also very, very thin, and they all go around
in the same direction. Galaxies, spiral
galaxies are one big disk with everything moving
around a common center. Disks seem to be something that
the universe likes to make. And, in fact, that really is true. And it has to do with
a number of things. It has to do with the force
of gravity and something called the conservation
of angular momentum. Now, gravity is very good at bringing
stuff together and bringing it together so it becomes denser and denser
and begins to fall into the center. Our solar system formed out of
a giant cloud of dust and gas about 4 and 1/2 billion years ago. It was actually many trillions
of miles across at first, but it had to get much smaller
in order for the densities to get high enough and
the temperatures also to get warm enough inside to give birth
to the Sun, actually ignite a star. So you have this
collapsing cloud of dust. OK, well, you can sort of
understand that gravity wants to bring all that together,
but why does it start to spin up? There’s something called the
conservation of angular momentum. And that basically says that if
anything has any spin at all, even just a little bit of motion, as
gravity brings it together and makes it smaller,
that spin is accelerated. It’s sped up. And probably the
example most people know best of all– you can
actually feel this if you want to do this– but an ice skater. If you’ve seen an ice skater
do a spin, usually what they do is that they have their
arms outstretched, and they’re spinning
around relatively slowly. And then they bring their arms in,
and they spin faster and faster. It’s kind of amazing that any person can
keep their balance when they do that. That is an application of the
conservation of angular momentum. You have an extended body, your arms
are out, and you’re spinning slowly. In order to conserve the energy in that
spin, as that body becomes smaller, the spin goes faster and faster. And so what happens in these
clouds is that a cloud usually has just a tiny little
bit of a drift velocity. It’s going around the galaxy or
maybe a nearby star exploded, and [? it’s ?] kind of all
moving in one direction. The cloud itself has a little bit
of velocity as a cloud, as a whole. Particles inside that cloud
could be going any which way. But as the cloud begins to come together
under gravity, any little bit of spin gets accelerated,
actually becomes faster. And so as the cloud collapses,
any little directional drift becomes a spin, and the cloud
itself begins to spin around. OK, so that gets you a spinning cloud. Why does it collapse down into a disk? And this is an interesting
bit of physics that has to do with things like collisions. In the case of a very large
cloud that’s forming a star, it might not even be that
things are colliding directly, but gravitationally they’re
influencing them as you go by. As you go by different parts
of mass, they tug on each other with their gravity. So this whole cloud is
spinning, and things begin to interact gravitationally. They begin to collide with each other. The particles have motion
in every direction. Some are going up, and
some are going down. And as they start to hit each
other, that’s kind of balanced out. It’s that up and down
is sort of canceled out, but everything has the same
motion as the cloud is spinning. So that’s basically the only
thing that’s left over at the end. Everything gets canceled out as all
these things collide and interact, but the spin of the
cloud is still there. And so over time, you
collapse down into a disk. So the only reason you
make disks is because of this law of conservation of angular
momentum, and the idea of gravity brings things together. Have those two things working
side-by-side, and you get a disk. And that’s why our solar
system formed that way. The planets then formed out
of that spinning disk of gas. So it makes sense that they’re
all going in the same direction. They all formed out of the gas
going around the Sun in that way.

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About the Author: Oren Garnes


  1. So, why are objects in those discs like stars and planets not discs themselfs? Don't they have a similar creation process of spinning gas comming together?

  2. If Venus didn't have the atmosphere that it has today due to a greenhouse effect – what would be the temperature then and could the planet sustain life?

  3. Disks are squares, it's a NASA hoax, if you imagine a square and then redraw it as a circle – what do you get? A disk. NASA has been doing this for the last 50 years to brainwash us. The Flat Earth Society approves this message.

    [just for a laugh – sarcasm mocking FES]

  4. Sure, the rule about angular momentum makes stuff spin FASTER, but why do they spin in the SAME PLANE (which was the question).

  5. Don't disturb circles.
    Abel prize 2019 on bubbles.
    Pi number collisions 3b1b.
    Strange places Pi appears in math.
    Lowest level of energy…tendency.
    Circular hole vs rectangular one…where cracks go? Y, primes, Riemann zeta, ..
    Easiest way to move liquid out is spin. Because integral pieces goes to centre or zero as Heesch's number.
    X 5th postulate. HeXaGoN snowflake or prism has X parabolic..
    Light cone, Cherenkov r.

    Euclid should used circles. From there all is possible.
    Everything goes around squaring the circle. Knots even.


  6. Thaller is my favorite science explainer! I love her lectures, her true interest and enthusiasm just shines through and it's a joy to watch.

  7. I LOVE Ms. Thaller explaining science. She can make it so interesting and ALIVE!! This was just a great explanation of a sometimes difficult bit of physics.
    Jenn 💖 in Canada 🍁

  8. Gravity in conflict with centrifugal force equals balance. The earth orbits the sun, the solar system orbits the Milky Way. Etc etc etc etc
    The momentum of the orbiting object constantly wants to move in a straight line (ie outwards). This is centrifugal force. The force of gravity coming from the centre of the system, on the other hand is dragging the object towards itself. Balance between the two forces creates the orbit.

  9. Another explanation for the "disc" bit is the analogy of pizza dough. When a pizza chef makes a pizza, they start off with a big ball of dough. But when they throw the dough and spin it in the air, centrifugal effects cause the ball to flatten into a disc.
    (For those wondering, this doesn’t happen with planets because they’re too small and dense and not spinning fast enough to flatten. However, for very fast-spinning gas giants like Saturn, you do see a bulge. The diameter through Saturn’s equator is larger than its diameter from pole to pole because it’s spinning so fast.)

  10. And our solar system's disc is heavily tilted to the galactic disc as we undulate up and down through it. Love Dr. Thaller's Big Think!

    Does the Solar System Line Up with the Milky Way?

    'The good news is, you don’t have to take science’s word for this. In fact, you can check this out for yourself.'


    Are the planes of solar systems aligned with the plane of the Galaxy?


  11. Um, there's something I don't get about this explanation – If particles are coming into a cloud are coming in from all directions, why wouldn't they have roughly equal but opposite angular moments that cancel each other out as they collide?

  12. Those things colliding are colliding from all directions, not only from the future up and down. And some does not cancel, if they collide from almost the same direction. She show us collisions from up and down with her hands so we agree with her. I disagree. I would say that the flatening is a direct result of spinning.

  13. Thanks .. this is the first time I got a sense of these revolving objects.. thanks for simplifying to a common mans vocabulary..

  14. Or, considering the forces and principals at work, the disk is the most efficient shape. The sphere is the most efficient shape for stars and planets. The geodesic dome is the most efficient shape for homes. The Universe is efficient, humanity not so much, except for igloos.

  15. I just realized that what Michelle thaller just explained regarding things being flat in the universe like galaxies, she basically just explained something almost relating to the black hole. Since we just recently learned that the black hole is not really a hole at all , but some very flat looking thing of up and down matter colliding very fast from each direction. Damn she’s smart

  16. Hmmm… I think PBS SpaceTime did a slightly better job at this 😛
    3 Reasons for spining disks:
    1) Gravity (Imply center of mass)
    2) Conservation of Angular Momentum (Imply preferred statistical velocity about center of mass)
    3) 3D Space (Imply only one rotational axis about the center of mass)
    PS: yes, there is a possibility of 2 valid rotational axis about a center of mass within 4D space.

  17. I didn't seek this video but just recently found myself pondering the question.
    Such a succinct explanation!

  18. I can see how this works over time, but you would think that relatively new galaxies/solar systems that have not had that time would still be 'messy'. How come we don't see these 'messy' ones still forming? Almost like the older a galaxy/solar system is, the flatter it gets.

  19. michelle, you fat sweaty disgusting pig dressed as a woman from the 18th century, what the fuck are you talking about? You are a worthless piece meat piled higher than my threshold level.
    You are the fart stamp reminder on a chair where a real scientist ever set. You contribute nothing, but destroy and lie.
    I hope your father killed your mom when they realized who you are. You are the evidence that supports life after mental death.
    Why are you here with/for us, i question.
    We don't need a puppet like you. Justify your existence! Justify your paycheck! Prove anything you say!
    You fucking kidney stone.

  20. But, uh, um, hey! Then why aren't spinning planets and spinning stars shaped like disks instead of spheres?

  21. Conservation of angler momentum only works because of gravity so the answer is simply because of gravity.

  22. I really like 'Big Think' because it introduces the 'Problem',' and in this case the disc form of creation. In that regard, we must notice that the 'Spiral' is present in all we see; from the Nautilus, to the form of flowers! In this issue, the responsible agent is claimed to be: Gravity! However, what is 'Gravity?' Is it a curvature of space in the presence of mass, as Einstein theorized? Or, is it the combination of all the forces of all the mass: Electricity and Magnetism from the proton, neutron, electron energies of all the mass present in an object – like the Earth, atmosphere and all the 'Mass' upon it?
    Not bending space, but electromagnetic forces which formed the universe and can be, and have been demonstrated in experiments which mirror reality …? The Plasma Universe is the future and Plasma Physics means success for the brilliant who study it …!!!

  23. So many things Spin. Not just in space. Storm systems, whirlpools, all the way down to atoms and subatomic particles. God loves to make things whirl and so He whimsically made all sorts of spinning things on the Earth, below the Earth and in the Heavens. Because Man is made in the image of God, so too, then does Man take delight in the creation and experience of spinning things. From toy tops to turbines. Basketballs to ballistic missiles. Bullets to ballerinas. Dancers to dervishes. Motors, gyroscopes, yoyos and whirligigs. What child has not delightfully spun around and around until falling down laughing with dizziness? 🤣

  24. Magic gravity 🤣😂🤣😂. Start by explaining what exactly "gravity" Is!! And how it works!! Ohhh but you can't. No one can. Because its magical gravity. No one knows what it is, or where it comes from, or what makes it work. Its just magic 😂🤣😂🤣😁

  25. So, the universe likes to make discs not spheres. why does this not also apply to the shape of the earth and other planets since they were supposedly formed the same way?

  26. this legit explains why water spirals into drains and I've been wondering about that for MONTHS! god bless this channel and Michelle, thanks so much 🙂

  27. I can see why she hardly explain why a spining object turn into a disc, she is dying the existing of centrifugal force, just like earth orbiting the sun, she said following the curvature of space.
    The formation of a disc from a rotating/spining object is best explain with centrifugal force.

  28. It's amazing how stupid people believe bigbang isn't an explosion yet they mention hundreds of times there is an explosion inside of it. There is no such proof of how the planets start spinning, but there are tons of assumptions and they made a theory out of it.

  29. You make all of this so easy to understand. I really enjoy listening and watching your videos. I am learning a lot. Thanks.

  30. This explanation is just too far fetched, it's completely theoretical, is they any empirical evidence out there to support this theory? Do we have any evidence of a star formation from clouds, then spinning clouds and then the packing to the core, there is evidence of a collapsing star but I am specifically asking for star formation from clouds? So far none. Of the trillions of stars no observed evidence of even one star formation. This explanation is just pure theory – a fantastic explanation at that…

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