Rotational Motion of Celestial Body

Click For Summary
SUMMARY

The discussion centers on the rotational motion of celestial bodies, specifically the Earth. It establishes that the Sun's gravity provides the centripetal force necessary for Earth's orbit, while the conservation of angular momentum from the solar system's initial cloud accounts for its rotation. External torques, primarily from the Moon and Sun, influence the Earth's rotation by affecting tidal forces, leading to a gradual increase in the length of a day over geological time.

PREREQUISITES
  • Understanding of gravitational forces and centripetal motion
  • Knowledge of angular momentum conservation principles
  • Familiarity with the effects of tidal forces on planetary rotation
  • Basic concepts of rotational dynamics
NEXT STEPS
  • Research the effects of tidal forces on Earth's rotation
  • Explore the conservation of angular momentum in celestial mechanics
  • Learn about the historical changes in Earth's day length
  • Investigate the role of external torques in rotational dynamics
USEFUL FOR

Astronomers, astrophysicists, and students of planetary science will benefit from this discussion, particularly those interested in the dynamics of celestial motion and the factors influencing planetary rotation.

Harmony
Messages
201
Reaction score
0
I understand that the Sun's gravity force provides the centripetal force for the Earth to orbit around it. However, what provides the torque for the rotational motion of Earth?
 
Astronomy news on Phys.org
The planets rotate due to the conservation of angular momentum of the initial cloud that formed the solar system.
 
An external force is required to change an object's linear momentum. The same concept applies to rotational behavior as well. An external torque is required to change an object's angular momentum. No torque is needed to keep the Earth rotating about its axis. A torque would change the rotational motion.

That said, such external torques exist. The moon and sun act through the tides to slow the Earth's rotation rate. A day was considerably shorter when the Earth first formed than it is now.
 

Similar threads

Stargazing Astronomy: Orbit Terminology
  • · Replies 39 ·
2
Replies
39
Views
2K
Undergrad About the relation between number of sidereal and solar days
  • · Replies 27 ·
Replies
27
Views
4K
Undergrad How our Moon and Sun may affect Earth's equatorial bulge
  • · Replies 3 ·
Replies
3
Views
1K
Undergrad How many degrees / radians is one full orbit of the Earth?
  • · Replies 8 ·
Replies
8
Views
3K
Undergrad Speed of the umbra during eclipse vs rate of the Earth's rotation
  • · Replies 3 ·
Replies
3
Views
2K
Undergrad The solar system and the Coriolis effect
  • · Replies 4 ·
Replies
4
Views
3K
High School Why do most of the celestial bodies rotate about their axis?
  • · Replies 10 ·
Replies
10
Views
4K
Undergrad Unexpected findings in need of an explanation (retrograde motion of Mars)
  • · Replies 83 ·
3
Replies
83
Views
5K
Undergrad How Can We Measure Properties of Distant Planets and Stars?
  • · Replies 12 ·
Replies
12
Views
3K
Graduate Inquiry Regarding Concept in Time and Celestial Motion
  • · Replies 2 ·
Replies
2
Views
3K