Does every orbiting object have spin

  • Thread starter Moazin Khatri
  • Start date
  • Tags
    Spin
In summary, the conversation discusses the rotation of the moon and its consistent facing towards Earth due to tidal deformation. The question is posed about whether a basketball thrown in a circular orbit around Earth would also have a consistent orientation or a faster spin. The expert explains that the object would spin at the rate it is thrown, but over time tidal deformation could change its orientation. The conversation also delves into the use of artificial satellites and how they are oriented in space. The expert suggests that small steering jets may be used to maintain orientation.
  • #1
Moazin Khatri
29
1
Our moon rotates around Earth in such a way that we always see the same face. But Earth orbits Sun in a different way. It keeps spinning. My question is, If I were to go to space and put a basketball in a circular orbit around Earth in such a way that at the time I throw it a particular face is facing Earth would it orbit Earth like the moon does(always the same face) or would it have a much faster spin?
 
Physics news on Phys.org
  • #2
Moazin Khatri said:
Our moon rotates around Earth in such a way that we always see the same face.
No coincidence, but the ultimate result of tidal deformation.

Your baseball would spin at whatever spin rate you give it when throwing. If you throw exactly hard enough for a circular orbit and don't give it any spin, it wouldn't rotate, just orbit. (i.e. on your location on Earth you always see the same side, but your antipodes see the opposite side). In the long run this tidal deformation might change that -- see link.

Think of the central character of the gravitational force and conservation of angular momentum.
 
  • #3
BvU said:
No coincidence, but the ultimate result of tidal deformation.

Your baseball would spin at whatever spin rate you give it when throwing. If you throw exactly hard enough for a circular orbit and don't give it any spin, it wouldn't rotate, just orbit. (i.e. on your location on Earth you always see the same side, but your antipodes see the opposite side). In the long run this tidal deformation might change that -- see link.

Think of the central character of the gravitational force and conservation of angular momentum.
Thanks for your answer. Just clear one more thing .. Just to confirm If I have properly understood what you're saying...
If instead of a baseball I use a physical arrow .. throwing it hard but no spin at all .. is it true that in its circular orbit there will come a time when the arrow will be parallel to the surface of the Earth and there will also come a time when it will be perpendicular?
And if this is true then why is it that whenever we see pictures of artificial satellites like ISS orbiting Earth .. their main body seems parallel to the surface of earth? Do they add spin when they launch it?

P.S: The arrow thing will only be true if velocity vector is parallel to the body of the arrow .. If it is perpendicular then it will always remain parallel to earth. And the same might be true with ISS. Looking forward to your reply!
 
  • #4
The consequence of what I wrote would indeed be as you describe: orientation in space invariant, so wrt Earth center it will rotate once per orbit.
ISS and other earth-facing satellites will probably be oriented properly with small steering jets.

@haruspex: are you aware of any mechanisms that would be helpful (or unhelpful) in this ?
 
  • #5
BvU said:
The consequence of what I wrote would indeed be as you describe: orientation in space invariant, so wrt Earth center it will rotate once per orbit.
ISS and other earth-facing satellites will probably be oriented properly with small steering jets.

@haruspex: are you aware of any mechanisms that would be helpful (or unhelpful) in this ?
Hmm... Thank You
 
  • #6
BvU said:
The consequence of what I wrote would indeed be as you describe: orientation in space invariant, so wrt Earth center it will rotate once per orbit.
ISS and other earth-facing satellites will probably be oriented properly with small steering jets.

@haruspex: are you aware of any mechanisms that would be helpful (or unhelpful) in this ?
I agree with what you posted. All objects would be subject to some tidal deformation, and over time that would lead to tidal locking.
Some satellites would be set into a one spin per orbit mode deliberately, so tidally locked from the start. Others might need to be in constant sidereal orientation, so might need a very small jet to maintain that. But without doing the calculation, I would guess the effect is small compared with, e.g., the solar wind on the solar panels.
 
  • Like
Likes BvU

Related to Does every orbiting object have spin

1. Does every orbiting object have spin?

Yes, every orbiting object has spin. This is because spin is a natural property of objects that have mass and are in motion. The spin of an object is its intrinsic angular momentum, which is dependent on the object's shape, size, and mass distribution.

2. How does spin affect an orbiting object?

The spin of an object affects its stability and orientation in orbit. An object with a faster spin will have a higher angular momentum, making it more difficult to change its direction or orientation. This can affect the object's trajectory and stability in its orbit.

3. Can the spin of an orbiting object change over time?

Yes, the spin of an orbiting object can change over time. This can happen due to external forces, such as gravitational interactions with other objects or tidal forces from the body it is orbiting. The spin can also change due to internal processes, such as collisions or changes in mass distribution.

4. How is the spin of an orbiting object measured?

The spin of an orbiting object can be measured using various methods, depending on the object's size and distance. For larger objects, such as planets or stars, scientists can measure the rotational period by tracking changes in their brightness or using radio waves. For smaller objects, such as asteroids or moons, spacecraft missions can provide information about their spin through imaging or gravity measurements.

5. Is the spin of an orbiting object related to its orbital speed?

No, the spin of an orbiting object is not directly related to its orbital speed. The two are independent properties of the object. However, the spin of an object can indirectly affect its orbital speed if it is experiencing external forces that change its angular momentum, such as gravitational interactions with other objects.

Similar threads

Replies
4
Views
819
  • Classical Physics
2
Replies
58
Views
4K
Replies
9
Views
3K
Replies
3
Views
1K
Replies
3
Views
1K
Replies
8
Views
2K
Replies
4
Views
619
  • Special and General Relativity
2
Replies
39
Views
3K
Replies
86
Views
4K
  • Classical Physics
Replies
1
Views
790
Back
Top