Why Do All the Planets Orbit in the Same Plane?

[MULTIZ321]

Why Do All the Planets Orbit in the Same Plane?
By Ethan Siegel/ Science/ Whoascience/ Forbes/ forbes.com

"Our Solar System is an orderly place, with the four inner planets, the asteroid belt, and the gas giant worlds all orbiting in the same plane around the Sun. Even as you go farther out, the Kuiper belt objects appear to line up with that same exact plane. Given that the Sun is spherical and that there are stars appearing with planets orbiting in every direction imaginable, it seems too much of a coincidence to be random chance that all these worlds line up. In fact, practically every Solar System we’ve observed outside of our own appears to have their worlds line up in the same plane, too, wherever we’ve been able to detect it. Here’s the science behind what’s going on, to the best of our knowledge.

The eight planets of the Solar System orbit the Sun in almost an identical plane, known as the Invariable Plane. This is typical of solar systems as we know them so far.


Richard

 

[bullroc3]

It was designed that way.

 

[Talent312]

I'll bet that plane is from Spirit Airlines.
Or is that a different plane of existence.
.

 

[Steve Fatula]

Well, we do know they basically do in our solar system, but, really don't know about other solar systems are it's hard to measure from distances like those. There is the curious WASP-17b which orbits the opposite direction. And we know Kuiper belt objects do not follow the plane.

 

[T_R_Oglodyte]

Well, we do know they basically do in our solar system, but, really don't know about other solar systems are it's hard to measure from distances like those. There is the curious WASP-17b which orbits the opposite direction. And we know Kuiper belt objects do not follow the plane.

Which suggests that objects that don't share the plane are captured objects.

An interesting article. It mentions angular momentum, but doesn't carry that far enough, particularly regarding why the central star doesn't simply collect all of the outlying material.

For those unfamiliar, angular momentum is what a figure skater uses when making a spin. At the same rotational speed, the further the object is from the axis of rotation, the greater the angular momentum. When the skater brings arms and the free leg in toward the body, the spin rate increases so that angular momentum is conserved.

What does that mean when forming planetary systems? As the star builds mass from the dust cloud, it has to start spinning faster to conserve angular momentum. But when something starts spinning faster, centrifugal forces cause material to start flying outward. And when the material is gas, there nothing to hold it in when.

So at some point the star can't continue collecting gas from the disk; it ejects as much material as it collects. That leads to a gaseous disk surrounding the star. Then within that disk, gravitational irregularities occur, and smaller objects form within the cloud.

*******

What none of this explains, though, is where did Earth's moon come from?

 

[MULTIZ321]

Which suggests that objects that don't share the plane are captured objects.

An interesting article. It mentions angular momentum, but doesn't carry that far enough, particularly regarding why the central star doesn't simply collect all of the outlying material.

For those unfamiliar, angular momentum is what a figure skater uses when making a spin. At the same rotational speed, the further the object is from the axis of rotation, the greater the angular momentum. When the skater brings arms and the free leg in toward the body, the spin rate increases so that angular momentum is conserved.

What does that mean when forming planetary systems? As the star builds mass from the dust cloud, it has to start spinning faster to conserve angular momentum. But when something starts spinning faster, centrifugal forces cause material to start flying outward. And when the material is gas, there nothing to hold it in when.

So at some point the star can't continue collecting gas from the disk; it ejects as much material as it collects. That leads to a gaseous disk surrounding the star. Then within that disk, gravitational irregularities occur, and smaller objects form within the cloud.

*******

What none of this explains, though, is where did Earth's moon come from?

Hi Steve,

Timely question. I saw this article today:
Moon Was Spat Out by Giant 'Dust Doughnut' After Planetary Collision, say Scientists.

https://www.telegraph.co.uk/science...-doughnut-planetary-collision-say-scientists/

Richard