Computer modeling of motion of planets

In summary: This would cause all sorts of big problems, since the moon is already orbiting the Earth, and now it's also orbiting the new, more massive moon.If you assume the moon doesn't get more massive, then the change in momentum and energy will be very small. You might be able to see a tiny change in the Earth's orbit, but it would be very hard to measure.In summary, if the mass of the moon will gradually increase within a day and becomes greater than the mass of the earth, it will bring a big disaster in the earth? will moon escape out of the Earth's orbit or Earth will start rotating around moon? or moon becomes another planet of the sun?
  • #1
eminent_youtom
47
0
computer modeling of motion of planets!

hi everybody
what would happen on the position and orbit of the Earth and the moon, if the mass of the moon will gradually increase within a day and becomes greater than the mass of the earth. will it brings a big disaster in the earth? will moon escape out of the Earth's orbit or Earth will start rotating around moon? or moon becomes another planet of the sun?
this change in mass of the moon will effect on the orintation of the other planets in the solar system or not?

Is it possible to do computer modeling of it? what software i have to learn?
thankx you
 
Physics news on Phys.org
  • #2
The Earth and the moon both orbit around their common centre of gravity. Since the Earth is much larger this centre of gravity is very close to the centre of the earth. As the mass of the moon increased the centre would move closer to the moon, if they were the same mass it would be half way.
Both objects would continue to go around the sun in the same way,

Such a small change in mass wouldn't have much effect on the rest of the solar system, the only object that has any real effect other than the sun is Jupiter - which is quite a bit larger.

You could model the movement in anything you like - but you probably have to understand some simple Newtonian gravity first.
 
Last edited:
  • #3
mgb_phys said:
The Earth and the moon both orbit around their common centre of gravity. Since the Earth is much larger this centre of gravity is very close to the centre of the earth. As the mass of the moon increased the centre would move closer to the moon, if they were the same mass it would be half way.
Both objects would continue to go around the sun in the way,

Such a small change in mass wouldn't have much effect on the rest of the solar system, the only object that has any real effect other than the sun is Jupiter - which is quite a bit larger.

You could model the movement in anything you like - but you probably have to understand some simple Newtonian gravity first.


i don't agree that"Both objects would continue to go around the sun in the way". if you know the KAM theory,you will consider it from a new viewpoint.
you can google the relation between the stability of sun system and the KAM theory
 
  • #4
The moon can't spontaneously change it's mass, so its difficult to interpret this question.

I think you may be interested in the general question of the stability of satellites. If you are, there has been theoretical work done and people here have also done simulations. (But I haven't been able to find the thread where people have done simulations, I know the author was tony873004.) But he has a program that is called "gravity simulator" that allows for such simulations, and I believe there may be other freeware programs out there that do similar things. Don't expect astonishingly great accuracy from them, though, the numerical techniques used are not necessarily state of the art.

As far as the theory goes, see for instance the "hill sphere" at
http://apollo.cnuce.cnr.it/~rossi/publications/napoli/node2.html [Broken]

also some some plots at
http://www.geocities.com/syzygy303/

The short (and approximate) answer is this: If the orbit of a satellite (in this case the Earth) around some other massive body, lies within the solar Lagrange points L1 and L2 of said massive body and the sun, the Earth's orbit will be restricted to a finite region, it won't be able to escape.

This happens because the Jacobi integral is a conserved property of motion. (The Jacobi integral is just the Hamiltonian, its existence is guaranteed by the conservation of energy).

See http://map.gsfc.nasa.gov/m_mm/ob_techorbit1.html for the Lagrange points, again the Lagrange points of interest are the ones between the sun and the massive body around which the Earth is orbiting.

Because said massive body is heavier than the Earth, these solar lagrange points will be closer to the massive body than the current Earth-Sun Lagrange points, making the maximum stable orbit smaller.

This result is exactly true only if there are no other bodies in the solar system, and the derivations I've seen only cover the case where we can ignore the mass of the Earth relative to the mass of the object it's orbiting around.
 
Last edited by a moderator:
  • #5
As pervect says it's hard to know what you mean by "the moon changing its mass".

If you make a model, the answers will depend strongly on what you do mean by that statement. If you assume the moon magically gets more massive, then it will also magically get more momentum and more energy (M.V and M.V^2/2) at the same time.

On the other hand if you assume it gets more massive by collecting material moving at a different velocity (e.g. it collides with another object) the energy and momentum will be different.

I've never tried this on an astronomical system, but I have done some serious computer simulations on "open" systems that gain and lose mass, and getting the correct momentum and energy changes when material enters and leaves the part of the system that is being simulated is critically important.
 
  • #6
thankx everybody
AlephZero said:
As pervect says it's hard to know what you mean by "the moon changing its mass".

oh you i was just doing thought experiment with my friend, so i consider that the moon magically gain its mass

AlephZero said:
I've never tried this on an astronomical system, but I have done some serious computer simulations on "open" systems that gain and lose mass, and getting the correct momentum and energy changes when material enters and leaves the part of the system that is being simulated is critically important
can u link your simulation please
 
Last edited:

What is the purpose of computer modeling in studying the motion of planets?

Computer modeling allows scientists to simulate and predict the motion of planets in a controlled and precise manner. This helps in understanding the complex dynamics of celestial bodies and making accurate predictions about their future movements.

What factors are considered in computer modeling of planetary motion?

Computer models take into account various factors such as the gravitational pull of other planets, the rotation and tilt of the planet, and any external forces acting on it. These factors are crucial in accurately predicting the path and speed of a planet's motion.

How do scientists validate the accuracy of computer models for planetary motion?

One way to validate the accuracy of computer models is to compare the predicted results with actual observations of planetary motion. If the model's predictions align with the observed data, it is considered to be a reliable tool for studying planetary motion.

Can computer modeling help in predicting future planetary events?

Yes, computer models can simulate the motion of planets into the future, allowing scientists to predict upcoming celestial events such as eclipses or planetary alignments. These predictions can help in planning and conducting astronomical observations.

What are the limitations of computer modeling in studying planetary motion?

Computer models rely on certain assumptions and simplifications, which may not always accurately reflect the complex nature of planetary motion. Additionally, external factors such as gravitational pull from other objects in the universe can also affect the motion of planets, making it difficult to predict with absolute certainty.

Similar threads

  • Astronomy and Astrophysics
Replies
1
Views
1K
  • Sci-Fi Writing and World Building
Replies
21
Views
852
Replies
4
Views
669
  • Introductory Physics Homework Help
Replies
18
Views
1K
  • Astronomy and Astrophysics
Replies
24
Views
1K
  • Science Fiction and Fantasy Media
Replies
2
Views
1K
  • Astronomy and Astrophysics
Replies
4
Views
2K
  • Aerospace Engineering
Replies
19
Views
2K
Replies
17
Views
2K
  • Special and General Relativity
Replies
10
Views
1K
Back
Top