What causes retrograde rotation in planets and moons?

In summary, the conversation discusses the rotation of planets and moons in our solar system and how it can be affected by external forces such as impacts. Specifically, the conversation mentions the retrograde rotation of some planets and the possibility of it being caused by past collisions or tidal interactions. It also touches on the naming scheme for moons orbiting Uranus and the potential for planets and moons to be knocked off their original axis of rotation due to chaotic events in the early solar system.
  • #1
Avimanyu Ray
17
1
When I googled it, I wasn't satisfied with the answers from various sites...some sites like universetoday.com gave me a glimpse but it was totally theoretical and based on assumption.
Also I would like to know why some planets have retrograde rotation; what might have caused them to and why do they not return to their original rotation? I assumed they originally rotated anticlockwise...
 
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  • #2
Our solar system started with a (more or less random) total angular momentum. As result, all the planets orbit in nearly the same plane, and most planets also rotate in this plane and with the same direction.
The rotation of planets only changes if something hits them or if something leads to a significant torque.

Something slowed down Venus - probably tidal interactions with its dense atmosphere, but impacts could have contributed.

Uranus has a weird axial tilt - probably from impacts.
 
  • #3
If it was specifically this link that triggered
Avimanyu Ray said:
I wasn't satisfied with the answers from various sites...some sites like universetoday.com gave me a glimpse but it was totally theoretical and based on assumption
then I don't think much can be done to improve your satisfaction ...:frown:
It seems quite plausible to me and I assume that's about the best you can get -- after all there aren't any witnesses. I'm not sure we have enough info from planets in other solar systems to improve on this.
 
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  • #4
Would a moon of Uranus that rotates in the opposite direction of Uranus be considered to have progade rotation because it rotates the same way as the Sun?
 
  • #5
The naming scheme follows the rotation of Uranus. The five big moons and the smaller inner moons all orbit in the same plane as Uranus' rotation. The outer irregular moons mainly orbit retrograde.
 
  • #6
Retrograde orbit or retrograde rotation?
 
  • #8
lifeonmercury said:
Retrograde orbit or retrograde rotation?
Retrograde rotation
 
  • #9
Moons and planets sometimes get 'bumped' off their original axis off rotation. Uranus, for example, evidently had a fender bender in the past that left it tilted sidewise. It is essentially impossible to pin down when these nudges may have occurred. The early solar system is believed to have been a very busy place. Numerous planetesimals were vying for promotion and coalescence was the means. These events were not necessarily gentle.
 

1. What causes the Earth to rotate?

The Earth rotates due to its initial angular momentum, which was caused by the gravitational force during its formation. As the Earth cooled and contracted, its rotation speed increased due to the conservation of angular momentum.

2. Why does the Earth rotate in one direction?

The Earth rotates in one direction because of the same initial angular momentum mentioned above. As the Earth formed from a rotating disk of gas and dust, it inherited the direction of rotation from this disk.

3. How fast does the Earth rotate?

The Earth rotates at a speed of approximately 1,037 miles per hour at the equator. This speed decreases as you move towards the poles.

4. Does the Earth's rotation change over time?

Yes, the Earth's rotation is gradually slowing down due to the tidal forces from the moon and the sun. However, this change is very slight and not noticeable to us on a daily basis.

5. What would happen if the Earth stopped rotating?

If the Earth stopped rotating, the side facing the sun would become extremely hot, while the side facing away from the sun would become extremely cold. This would have a catastrophic effect on the Earth's climate and ecosystems, potentially leading to the extinction of many species.

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