You're spinning and I'm spinning and the Earth is spinning and the sun is spinning and the
solar system and the WHOLE DAMN GALAXY.
BUT WHY!
You might remember from our "How Fast Is the Universe Moving" video that you're moving
really fast right now.
For example, the Earth is rotating around it's axis at 1,040 miles per hour (465 m/s).
Planets rotate.
That's what they do, right?
But then science comes along and asks WHYYY… and once you start thinking about it, it's
staggering.
To figure it out, we have to go back to the beginning.
Four and a half billion years ago, our solar system began to form from clouds of helium
and hydrogen -- kind of like a nebula.
As the gas was moved and undulated through the universe, some of it was denser and some
thinner.
Something, perhaps a nearby supernova, caused the gases to begin to coalesce, and as the
gravity of these particles increased, they fell toward each other -- and began to spin.
Funnily enough, every time this happens, the spin rotates the same direction, counter-clockwise.
There's no UP in space, of course, but if you think about the angular moment of the
spin as a FORWARD direction, then most things, Earth, Mars, the Sun… they all rotate counterclockwise.
Because they're all conserving their angular momentum.
As the gases continued to gravitate toward each other, constantly moving, they formed
a tossed pizza dough shape.
A ball in the middle, slowly expanding outward into a disc.
This is the shape we see most often in the universe, because of the laws of physics.
As interstellar clouds rotate and collapse onto themselves they fragment, according to
Scientific American, and then those smaller parts collapse again, and again.
And over the next few hundred million years, all that gas gathers and fuses into suns,
planets, asteroids and (eventually, after lots more time) you and me!
All the while, the angular momentum of the original cloud it maintained; that original
gaseous angular momentum set the stage for all the rotation to follow -- inertia keeps
it going.
Yes, it IS slowing over time.
A day in 100 years will be 2 milliseconds longer, but ultimately we'll all keep spinning
unless something big smacks into us.
Strangely, Venus rotates clockwise, and we're not sure why.
Either the axis of the planet was flipped upside down at some point, or it slowed rotating
counterclockwise, stopped and began to rotate the opposite -- possibly due to its dense
atmosphere and closeness to the sun.
It's not the only weirdo; Uranus was knocked on it's side, her rotation is ALL screwed
up.
Even on a macro level, everything is spinning.
But galaxies, relative to Earth, spin both clockwise and counterclockwise.
Though spiral galaxies DO tend to spin with their arms trailing behind them, but even
that isn't a hard rule.
In 2002, the Hubble spotted galaxy NGC 4622 whose arms LEAD her rotation, but they believe
it's because it interacted with another galaxy.
Sounds hot.
In the end, everything in the universe is spinning.
Energy must be preserved over time; so when a figure skater spins with his arms in, he'll
spin faster, but with his arms out he'll move slower.
That's simple physics, but it operates on a galactic level too!
Does a science question have your head spinning??