Thanks to the wonder of the Internet, I've been checking out something that's pretty interesting. I always thought the disc-shaped solar system, and disc-shaped galaxies, were just representations of a likely spherical group of objects. My question is: why?
An hour-long Google session didn't really help. Mostly the only information I can find on the subject is definitions of what the ecliptic plane is, or just statements that basically amount to "it happens during formation of the systems", which isn't really an explanation.
I assume there's some sort of mathematical explanation for why massive groups of rocks in the universe tend to circle each other within a plane; what is it?
I Googled "why are galaxies flat" and I was about to link you a bunch of stuff I found but I think it's more efficient to have you sort through it. This thing is pretty, though.
You're not going to get a simple mathematical explanation for something as complex as the orbits of all the bodies in a solar system or galaxy. And of course, not all orbits in the system are actually on the same plane, they just statistically tend to fall on or near a plane, but there are of course outliers. So it's a statistical representation, not an absolute fact for all bodies in orbit around a point.
When you take a particle system operating under gravity (eg: gasses in a nebula, stars in a galaxy) and make them spin they will end up in a flat(ish) spinning disk shape.
It is the spin of a galaxy / star system that results in them being "flat".
edit: Try and find a copy of Neil Degrasse Tyson's series of lectures "My Favorite Univerise". One of them explains this very well.
RiemannLives on
Attacked by tweeeeeeees!
0
Options
Mojo_JojoWe are only now beginning to understand the full power and ramifications of sexual intercourseRegistered Userregular
Thanks to the wonder of the Internet, I've been checking out something that's pretty interesting. I always thought the disc-shaped solar system, and disc-shaped galaxies, were just representations of a likely spherical group of objects. My question is: why?
An hour-long Google session didn't really help. Mostly the only information I can find on the subject is definitions of what the ecliptic plane is, or just statements that basically amount to "it happens during formation of the systems", which isn't really an explanation.
I assume there's some sort of mathematical explanation for why massive groups of rocks in the universe tend to circle each other within a plane; what is it?
They're not all on quite the same plane, but the general idea is that if you take these sphere of stuff and drop a line though its centre around which it rotates, then the mass gets thrown to the outermost points. which is the plane perpendicular to the axis at its centre.
It's hard to explain without a diagram.
Mojo_Jojo on
Homogeneous distribution of your varieties of amuse-gueule
^ if the rate of spin is sufficient enough to outweigh the force holding that mass together (mostly gravity). There's a reason why Earth (and pretty much most planets) are spherical and not disc shaped. In short, those galaxies are rotating really fast.
Demerdar on
0
Options
SmasherStarting to get dizzyRegistered Userregular
^ if the rate of spin is sufficient enough to outweigh the force holding that mass together (mostly gravity). There's a reason why Earth (and pretty much most planets) are spherical and not disc shaped. In short, those galaxies are rotating really fast.
Although even Earth is a few dozen miles shorter pole to pole than it is equator to equator.
Posts
It is the spin of a galaxy / star system that results in them being "flat".
edit: Try and find a copy of Neil Degrasse Tyson's series of lectures "My Favorite Univerise". One of them explains this very well.
They're not all on quite the same plane, but the general idea is that if you take these sphere of stuff and drop a line though its centre around which it rotates, then the mass gets thrown to the outermost points. which is the plane perpendicular to the axis at its centre.
It's hard to explain without a diagram.
Although even Earth is a few dozen miles shorter pole to pole than it is equator to equator.
Same idea, generally.
he has more than enough material to keep you occupied for weeks on end, and I have personally never been bored by his lectures