What causes retrograde rotation in planets and moons?

Click For Summary

Discussion Overview

The discussion centers on the causes of retrograde rotation in planets and moons, exploring both theoretical and observational aspects. Participants examine the mechanisms behind retrograde motion, including impacts and tidal interactions, while also questioning the reasons some celestial bodies do not revert to their original rotation.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • Some participants express dissatisfaction with existing explanations for retrograde rotation, suggesting that many are theoretical and based on assumptions.
  • One participant proposes that the solar system's initial angular momentum led to the current rotation patterns, with changes occurring due to impacts or significant torques.
  • It is suggested that Venus's retrograde rotation may have been influenced by tidal interactions with its atmosphere, along with potential impacts.
  • Uranus's unusual axial tilt is attributed to past impacts, raising questions about the history of its rotation.
  • Participants discuss the classification of moons based on their rotation relative to their planet and the Sun, leading to questions about terminology and definitions.
  • One participant notes that moons and planets can be "bumped" off their original rotation axes, with the early solar system being a chaotic environment that contributed to such changes.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the causes of retrograde rotation, with multiple competing views and uncertainties remaining about the mechanisms involved.

Contextual Notes

Some discussions highlight the limitations of current knowledge, including the lack of direct evidence for historical events that may have influenced planetary rotation and the challenges in interpreting data from other solar systems.

Who May Find This Useful

This discussion may be of interest to those studying planetary science, astrophysics, or anyone curious about the dynamics of celestial bodies and their rotational behaviors.

Avimanyu Ray
Messages
17
Reaction score
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...
 
Astronomy news on Phys.org
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.
 
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.
 
  • Like
Likes   Reactions: Avimanyu Ray
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?
 
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.
 
Retrograde orbit or retrograde rotation?
 
lifeonmercury said:
Retrograde orbit or retrograde rotation?
Retrograde rotation
 
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.
 

Similar threads

Undergrad What Could Cause the Earth's Rotation to Dramatically Slow Down?
  • · Replies 39 ·
2
Replies
39
Views
8K
Undergrad Is there an experimental proof that an Earth/Moon barycenter exists?
  • · Replies 51 ·
2
Replies
51
Views
7K
Undergrad Rotation rates of planets seem odd?
  • · Replies 10 ·
Replies
10
Views
2K
Undergrad Tidal forces acting on planet NGTS-10b
  • · Replies 2 ·
Replies
2
Views
3K
High School Can a Planet Have a Moon that Never Casts a Shadow?
  • · Replies 19 ·
Replies
19
Views
3K
Undergrad Tidal effects on Earth's rotation and moon's orbit
  • · Replies 10 ·
Replies
10
Views
5K
Undergrad Question about a magnetic dynamo on tidally locked moons
  • · Replies 7 ·
Replies
7
Views
3K
Undergrad Research paper and sources investigating Earth's moons
  • · Replies 15 ·
Replies
15
Views
2K
Undergrad New Developments In The Search For Planet X
  • · Replies 2 ·
Replies
2
Views
3K
Graduate Effect of Rotation on the Earth and Planetary Disk(s)
  • · Replies 8 ·
Replies
8
Views
2K