Could (or have) a comet be so slow that instead of orbiting around the sun, the stronger gravitational pull of the sun make it collide with the sun? I know that the sun is supper hot and anything would probably evaporate first, but couldn't a big enough 'comet' actually hit the sun? what would happen if it DID happen?

Say for example, you set a bunch of rockets around the circunference of a planet, say Mars. and you program them to go of againts the surface, as to push the surface to the opposite direction of their orbital spin, as to slow it down, making it fall directly into the sun. Did that make sence? i hope it did. what would happen though?

Eh. Just a stupid, random question.

Thanks! 8)

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May the schwartz be with you!

Yeah, if a comet, or body that is a comet-to-be, has its orbit changed, by the gravitational effect of another body or bodies, or even a coliision, so that the orbitital path intersects the body of the Sun, then it will hit the sun, or evaporate trying. It happens. No big deal.

ESA: SOHO analyses a kamikaze comet

But if it is not so affected, if it is just in a stable orbit around the sun, it will remain in a stable orbit. It won't just suddenly decide to plunge into the sun because it feels like it.

And, welcome to the BABB.

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I'm shocked at the energy change required to produce such a drastic change in the orbit.

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Freedom For Fission A breath of fresh Iodine-131

Welcome to the BABB. Let's see if I can make any sense...

Comets have hit the Sun in the past. SOHO has recorded photo sequences of comets going behind (apparently) the Sun and not coming back out the other side. So the assumption is that they went smack.

But it's not a matter of speed that makes them hit. When the comet is closest to the Sun is when it's moving fastest. The reason it hits the Sun is that its orbit now happens to intersect the Sun. This generally happens because the orbit has been perturbed by another body. Typically, this other body is Jupiter, the second-largest mass in the Solar system.

Comets big and small can hit the Sun. When they do, there might be a detectable plume of gas as they vaporize. But the Sun in general would just go trundling along.

Oy. May I direct you to an old SF story, "Thundering Worlds" by Edmond Hamilton? Hard to find, probably only collected in the old SFBC collection The Best of Edmond Hamilton. The Sun is dying, so the inhabitants of all nine planets decide to install huge rockets on the planets and head off to another, younger sun. 1930's big-science space opera at its "best."

Back on topic. Let's make sure we're talking about the same thing. The planetary spin that makes day and night has nothing to do with the planet's orbit, which is what keeps it from falling into the sun. It sounds like your question is confusing the two ("a bunch of rockets around the circunference of a planet, say Mars. and you program them to go of againts the surface, as to push the surface to the opposite direction of their orbital spin"). Anyway. Assuming you can construct a rocket large enough to change a planet's orbital speed, and use constant thrust what happens depends on how strong the rocket is. In general, the planet will spiral into the sun. It will be a tight spiral with lots of loops for a weak rocket, a loose spiral with few loops for a very strong rocket.

But then comes the question, what do you use for rocket fuel? The easiest material is the body of the planet itself, and you use electromagnetic catapults to fling it away really fast (ignoring the question of where do you get the electricity to do so). But I'd bet that you'd run out of planet before you hit the Sun...

There are no stupid questions, only stupid answers.

Fred

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"For shame, gentlemen, pack your evidence a little better against another time."
-- John Dryden, "The Vindication of The Duke of Guise" 1684