Center of gravity of an orbitting body not at center of gravity

In summary, objects in low orbit around a neutron star or black hole experience a displacement of their center of gravity from their center of mass, with a stronger effect closer to the star. The strength of this effect is associated with the inverse fourth power and can have significant implications for tidal locking and the behavior of objects in orbit. This phenomenon is also present in orbiting spacecraft and can be detected even in microgravity. The cause of tidal locking involves a loss mechanism and can be compared to the effect of spaghettification on small planets in orbit near stars.
  • #1
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It just occurred to me that in the right gravitational field, say, in a low orbit 100 km from the core of a neutron star with a mass equal to that of the sun, an orbiting object's center of gravity is somewhat noticeably displaced from its center of mass. Specifically, 1 meter closer to the neutron star, there is about a 1.03 km/s^2 stronger gravity, obviously, this is a ludicrous amount of force that would quite like kill anyone at that altitude (if radiation and heat hadn't done that already). With a field strength variation that high (1030 square hertz) compared to the gravity of 51520 km/s^2. The gravity on a 1-meter dumbbell facing the neutron star will move the center of mass by about 1/100000th of a meter.
Or a more powerful example using low orbit of a black hole generating 1 G 10 meters away.
At 10 meters away, the variation is roughly 2 square hertz, so you would be fairly okay in terms of not being turned into spaghetti, but the previous dumbbell, or roughly speaking, a person, would experience roughly a 10 centimeter displacement in center-of gravity away from center off mass. This is all at non-relativistic speeds of about 10 m/s orbital velocity and non-relativistic gravity of 8-12 m/s^2.

Curiously, if I go out to 100 meters distant, the distance removed from the center of mass that the center of gravity is goes down by a factor of 100, e.g. It is proportional to the inverse square. However, the overall strength of the effect is therefore clearly associated with the inverse fourth power.
Which, taken to its logical extreme, means that at 1 meter, with a gravity of 100 G and a variation of 2 kilohertz/second (YAY for unit cancelation), this force would push the center of G 10/11ths of the way toward the hole. What effects does this have in real life, is it partially responsible for tidal locking?
 
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  • #2
Even in real life, the microgravity inside an orbiting spacecraft can be detected and will affect what objects will do inside it. The effect when bigger masses are involved will be correspondingly greater.

Tidal locking has to involve some loss mechainsm, I believe. Without friction effects, the mutual steady slowing down and speeding up of the two bodies would become oscillatory, energy passing back and forth between orbital and rotational forms. The tide, of course, happens because of the difference in gravitational attraction from place to place. There is an equivalent to 'spaghettification' with the atmospheres of small planets in orbit near to stars, when the higher velocity molecules happen to 'escape' up/down into the star when they reach the null between the two bodies.
 
  • #3
If you had a fluid on the object, it would slosh around.
If you stood on it, it would feel like it was wobbling.
 

Related to Center of gravity of an orbitting body not at center of gravity

1. What is the center of gravity of an orbiting body not at the center of gravity?

The center of gravity of an orbiting body not at the center of gravity is the point in space where the combined mass of the orbiting body and the body it is orbiting around is located. It is also known as the barycenter or the center of mass.

2. How is the center of gravity of an orbiting body not at the center of gravity calculated?

The center of gravity is calculated using the masses and distances of the two objects involved in the orbit. The equation for calculating the center of gravity is: r = (m1*r1 + m2*r2) / (m1 + m2), where r is the distance from the center of gravity to each object, m is the mass of each object, and r is the distance between the two objects.

3. Can the center of gravity of an orbiting body not at the center of gravity change?

Yes, the center of gravity can change depending on the relative positions and masses of the two objects. If the two objects have different masses or are at different distances from each other, the center of gravity will shift accordingly.

4. What are the implications of a center of gravity not being at the center of gravity for an orbiting body?

If the center of gravity of an orbiting body is not at the center of gravity, the orbit will be affected. The orbiting body will experience varying levels of gravitational pull from the body it is orbiting, causing its orbit to be elliptical rather than circular. This can also lead to changes in the speed and distance of the orbit.

5. How does the center of gravity of an orbiting body not at the center of gravity affect the stability of the orbit?

The stability of an orbit can be affected by the center of gravity not being at the center of gravity. If the center of gravity is significantly offset from the center, the orbit may become unstable and the orbiting body may eventually collide with the body it is orbiting. This can also lead to changes in the orientation and tilt of the orbit.

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