Why the solar system can exist

If gravity is so attractive, why doesn't the earth just crash into the sun? Or the moon into the earth?

The answer: Stable Orbits


And twitter - @minutephysics

Minute Physics provides an energetic and entertaining view of old and new problems in physics -- all in a minute!

Music by Nathaniel Schroeder

Thanks to Perimeter Institute for support.

[deathwilldie]

I'm getting the feeling you are really fond of

[LazerLord]

Wait a moment. If gravity was stronger, why would orbits not happen? Couldn't the planets just start with a higher velocity orbit that would counteract the higher gravity in the same way they do now? This may not be the right assumption, but I am curious.

[erikthegodeatingpenguin]

You said that we're lucky to live in a universe with stable orbits. However, that is not luck because if the orbits weren't stable, then we simply wouldn't be here to observe it.

[AHybrten]

Aaaaah. So THAT's what crashing is. So glad I watched this video

[Serkant]

Don t know how science lessons are in U.S. Schools, but this is fun and easy to watch

[megablater]

Things that happened today:
1. My teacher said if the Earth speeds up, we would fly off into space.
2. My teacher got hit in the face
3. I got expelled

[UnrealAngel]

I love the way sometimes you say, draw and write random things while still explaining pretty much a lot of science. Keep your good job!

[leroyjemini]

if gravity is so atractive, i think ill marry it!!

[TheGurumash]

I love that you defined crashing the way you did, Made me chuckle.

[rarebeeph]

0:58 But what if we completely mangled the laws of the universe with the intent of creating stable orbits in 4D? Would it be possible, given absolute control over math and physics, to create any set of rules in which stable, 4D orbits would be possible?

[FLS]

Thank you! I have always wondered this seemingly simple question and felt kinda stupid about it, but never really got a satisfying answer. This explains it. But one more question: why aren't the orbits perfectly spherical? Will they become such over very long periods of time, or are they caused by gravitational pull of other bodies in the solar system?

[samtew]

"Which is called crashing" LOL

[aquamurray]

Their orbit co-insides with the ground aka crashing. ← LOL

[Jaws]

Awesome!
didn't know that, thanks :)

[IAmTheBengineer]

Please explain why 2D and 4D orbits can't exist! Also, this might be cheating but couldn't you make a stable orbit in 4D space by only using 3D objects and trajectories?

[gregbyrne]

Do planetary orbits have to be parallel to each other?

[hernrybrown]

Thank you, this has been mind boggling for me before

[govind]

I was confused about this fact before.Now problem solved.
Thank You M Physics.

[emmettomeara]

"We're very lucky to be in a 3D universe, " he says after giving off a bunch of reasons why it's impossible to be alive in a 2D or 4D universe

Yup, very logic.

[Aaron.Reichert]

_"the only reason the coins in the funnels (or satellites around the earth) eventually DO spiral in to their doom is because they lose energy to friction and thus shift down from one stable orbit to another, until eventually, their orbit coincides with the ground. Which is called crashing."_