Why is the Solar System Flat?

Why is the Solar System Flat?

Our sun and the earth, and all the planets and moons and dwarf planets and asteroids and comets… The Solar System in short formed about 4.6 billion years ago from a nebulous cloud of swirling gas and dust which coalesced thanks to the irresistibly attractive force of gravity. However, this nebula started off more or less as a big shapeless blob. So how did our solar system end up with all the planets and their moons orbiting in a flat disk? I mean, we’ve all seen the planetary model of the atom, which is definitely wrong when applied to atoms. But it also kind of suggests that planets might revolve around the sun every which way. So is our solar system somehow special in its flatness? Or is the planetary model of the atom doubly wrong? Well, our solar system definitely isn’t alone. Many exoplanets’ star systems are flat, a lot of galaxies are flat, black hole accretion disks are flat, Saturn’s rings are flat, etc. So why, when there’s all of 3D space to fill, does the universe have this preference for flatness? The answer has to do with two things: collisions and the fact that we live in three dimensions. Bear with me. Anytime a bunch of objects held together by gravity are zooming and circling around, their individual paths are nearly impossible to predict. And yet, collected together, they have a single total amount that they spin about their center of mass. It may be hard to figure out exactly what direction that rotation is in, but the mathematics implies there must be some plane in which the cloud, taken as a whole, spins. Now, in two dimensions, a cloud of particles rotating in a plane is flat by definition, it’s in two dimensions. But in three dimensions, even though the rotation of the cloud is given by one plane, particles can whiz around far up and down from that plane. As the particles bump into each other, all the up and down motion tends to cancel out. It’s energy lost in crashing and clumping. Yet, the whole mass must continue spinning inexorably, because in our universe, the total amount of spinning in any isolated system always stays the same. So over time, through collisions and crashes, the cloud loses its loft and flattens into a spinning, roughly 2 dimensional disk shape, like a solar system or a spiral galaxy. However, in 4 spacial dimensions, the math works out such that there can be two separate and complementary planes of rotation, which is both really really hard for our 3D-thinking brains to picture and also means there’s no up and down direction in which particles lose energy by collisions. So a cloud of particles can continue being just that… a cloud. And thus, only in three dimensions can a nebula or infant galaxy start out not flat and end up flat which is definitely a good thing, because we need all that matter to clump together in order for stars and planets to form, and for us, even those of us who think atoms look like this, to exist. This episode of minute physics is supported in part by Embry-Riddle Aeronautical University, one of our subscribers

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About the Author: Oren Garnes


  1. next vid : MARS IS FLAT
    90 % comments : People have gone to next level, they are now flat mars'ers
    thanks for glamdrag for the thing

  2. https://youtu.be/5ZmykJbkBqg



    This is mi excplaination.
    Treu excperiencing en plasma science♡♧♡

  3. PROOFED! The Earth is actually flat, the universe are flat, even the flat earther brain also flat… WOW

  4. Found you because of the SciShow ! Absolutely love the way you explained why the Solar system is flat . You have a new subscriber ^_^

  5. If the solar system is flat how do u explain movement of the solar system with in the vortex spin of the milky way..the movement of the sun through the galaxy would pull the planet's like a cone not flat…

  6. Oh God, thank you good sir, this question was in my head for 20 years(since I was 5). Now I can die in peace.

  7. Video idea: how much aluminium foil would you need to lay on the ocean to have a significant impact on slowing down climate change.

  8. Okay. This is my question. If the universe is flat (according to the theory of relativity), I don’t understand why it is that when we look at the stars it seems like they are going across all three dimensions, including up/down. I probably just misunderstand a heck of a lot, but can someone please explain this?

  9. Birkeland Currents rotate for efficiency, form rotating plasmoids along the string, and eventually condensing into matter forming galaxies and systems. Please try to keep up.

  10. If everything move or spin in different directions in 3D universe then someday they will Collide and follow the spinning direction or motion of the strongest one. This will continues till the strongest spinning object remains and form a group in 3D universe i.e Black Holes. Now any other object which comes after forming of this group they have to give in to Gravity and follow them, forming a Galaxy.

    This is what I understand.

  11. The Solar System is not flat. Pluto’s orbit goes billions of miles tilted above Sun. Other dwarf planets like Eris, Ceres, Sedna, Makemake, and Hauméa have very tilted orbits. EVEN MERCURY HAS A TILTED ORBIT. Point being, the Solar System is nat flat.

  12. Is there a more detailed explanation? My current brain can only comprehend the part that the reason systems are flat is because of conservation of angular momentum 😓

  13. Umm so saturns rings are flat cause the rocks and dust that make it up lose too much energy going up and down?

  14. I get it. Just like if you take a glob or ball of pizza dough and you flip and spin it…. It fattens out

  15. Did you do the spinning by colouring multiple papers? Damn that must took lots of time and hard work.

  16. Simply our solar system is flat ,because gravity is a central force and particles interacting by a central force always have a constant angular momentum in magnitude as well as direction.

  17. the solar system isn't really flat, the planets just follow the suns trajectory that orbits around the milky way

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