# Calculating orbit

1. Jul 24, 2014

### Rohith8193

Is it possible to calculate the entire orbit of an interstellar piece of rock that has entered our solar system from observing the parameters and trajectory of that rock exhibits while inside our solar system?

2. Jul 24, 2014

### Student100

I think you may need to define "entire orbit" and "interstellar piece of rock" a bit better.

For the most part yes, we'd make optical observations over time and calculate, to the best of our abilities, it's orbit.

3. Jul 25, 2014

### Rohith8193

Well the interstellar piece of rock is an asteroid thats been travelling in our galaxy. The scenario is this:
The rock has entered our solar system and we began our observations on it from the moment it entered the Oort Cloud. from that time to the time it leaves the Oort cloud we were able to get a lot of data on it(data pertaining to its velocity, etc etc). From this will we be able to calculate its entire orbit as it travels through the galaxy?
What i mean is which all star systems is it likely to go through and all?
I'm working on a sci fi short story and this has been bugging me because the galaxy is riddled with massive objects and all of them will interact with the rock, so will it have a steady orbit?

4. Jul 25, 2014

### Student100

Would we be able to get a rough guesstimate, yes. It's likely that such an object would end captured by our solar systems gravitational well.

5. Jul 25, 2014

### Drakkith

Staff Emeritus
Calculating the entire orbit around the galaxy is probably not reasonable. We're talking about 200 million years of interactions with billions of large objects. At best you'd get a rough estimate with no real way to know the details.

It's unlikely to be captured by our solar system without some multi-body interactions that are pretty rare. It would most likely drift right by with only a change in direction.

6. Jul 25, 2014

### Bandersnatch

Consider this: it's possible to calculate every further and past position of a gravitationally interacting two-body system. Once you add the third body, the equations become impossible to solve, apart from certain restricted cases. All you can ever do then is make approximations.

7. Jul 25, 2014

### Chronos

The only object of consequence, gravitationally speaking, is the sun.

8. Jul 26, 2014

### Rohith8193

So there is no way of getting a defined orbit from just the data we obtain from the rock travelling through our solar system.
But if we had a an accurate Galactic map would we be able to predict the orbit taking into consideration all the bodies that could affect it?
Thanks for the replies till now :)

9. Jul 26, 2014

### Student100

We don't even know the orbits of the outer planets without error. We could certainly learn a few things about the rock, where it came from, where it's going, a rough orbit (if it's orbiting anything and hasn't reached galactic escape velocities). There's actually been studies done looking for interstellar meteoroids in our solar system, six possible canadites were found with a confidence of σ3. No smoking gun to date that I'm aware of. The event must be extremely rare on human time scales.

10. Aug 4, 2014

### puncheex

With three accurate positions of anything in 3space+time, one can calculate an orbit. If there is only one other body, then newtonian mechanics will do - you can compute the equation that will place it precisely at any time forwards or backwards. If there are more than two bodies involved, then you can still do an numerical, iterative solution using the theory of perturbations.