Comet Questions

[riddlemethis]

I have some rather uneducated simple questions about comets.

 

First - are all comets made of the same things, and if not what are the possible compositions?

 

Second - are the nuclei of all comets made of the same thing, and if not what are the possible compositions?

 

Third - what thing (other than direct impacts) can affect the orbit or path of a comet?

 

Fourth - do comets have a magnetic component?

 

Fifth - in regard to rotation, why do some comets spin asymmetrically while others spin symmetrically. What would cause the difference? Would it be the composition or shape nuclei of the comet or something else?

 

Sixth - what if any effect would a comet have on the sun in a close approach and why?

 

Seventh - what effect could the sun have on a close approaching comet and would it's composition change this answer in any way?

 

Eight - When comets approach the sun is their decomposition symmetrical or asymmetrical. If asymmetrical can asymmetrical degassing cause a change in trajectory? If not, why not?

 

Ninth - how and why are comet trajectories changed (for example by NASA) - is it simply observational?

 

Are there historical examples of comets approaching the sun and then breaking apart? Could a comet that broke apart near the sun survive the break-up or would the sun's gravity envelop the parts?

 

Thanks!

[Airbrush]

That many questions is a tall order for anyone. Start with a few and see if anyone wants to answer.

 

I will try at a few. Comets are all basically made of the same stuff, water ice and dust, in different proportions.

 

They rotate randomly according to outgassing that spins the comet every which way.

 

Gravity of any massive object will affect the comets path.

 

What affect can a comet have on the sun? How much effect does a fly have on an ocean liner?

Edited October 23, 2013 by Airbrush

[Enthalpy]

1) and 2) Too few comets are known in-situ. From distance, we observe only the degassing. For lack of better observation, comets are supposed to contain initially much snow, and after some passes close to the Sun, far less snow but still dust. Are there other variations? I bet the question is still open.

 

3) Heavy celestial bodies, especially Jupiter, when the comet is already that near to the Sun. In the Oort cloud: little known, because it's unexplored. The cloud has objects on very different paths, so if it has enough objects, near passes must deviate some comets towards us.

 

4) If they contain only snow and sand, no. But if some contain Fe₃O₄, or just carbon-loaded iron, these may have a small field.

 

5) I didn't understand "asymmetric rotation".

 

6) One was observed falling into the Sun. Not very spectacular, but a small gas emission was observed at the Sun's opposite side.

 

7) Fully evaporate the snow if there is still some. A really close approach may break the comet in parts as Jupiter did for Shoemaker-Levy.

 

8) The Giotto probe observed that the gas is emitted locally, in this case from several places, by the nucleus. From some distance, the aspect is uniform.

 

Influence on path: of course. That's only a matter of how much. Though, the gas emission must be slow, like 100m/s, so the effect is small.

 

9) As far as I know, no single comet has ever been deviated by humans up to now. Plans do exist: look for "Near-Earth Objects". Nothing obvious, but one scenario does want to evaporate some material of the object, so the reaction force pushes the object away. But it needs volatile materials at the object (less easy with iron or stone), and depending on the heat source, a rotation slow enough would be easier.

 

If you hoped to have invented the method, sorry. Painting the object is also proposed, as well as a tractor, and nuclear explosions, and impactors... Some methods might work if the object is small enough (...but still detected on time) and the necessary push is small enough and the trajectory accessible to our rockets, and and and. The more general case is pretty much out of reach.

 

10) Break apart: by the Sun I don't remember any, but by Jupiter yes. This alone is no reason to fall into the Sun: a celestial object continues on its path, as opposed to a shot duck. But the proximity to the Sun can mean that the next pass is a collision.