Comets

there was supposed to be a light show in the sky last night over the uk,from a comet(cant remeber its weird name!).

it was cloudy and late so went to bed and didnt see anything

got me thinking anyway.

how come comets seem to just go around space?is it just due to gravity from the planets pulling in a big orbit?

how far have comets been tracked to? if theyre flying around all the distance they do surely they pick up some space dust far out there.

also if theyre made of ice, where did the ice come from,i know its cold up there but it was made somewhere,also i dont know much about space but,in a gravity less and frictionless enviroment a small push on an object would see it carry on at that speed for infinity? what makes comets fly at these high speeds,gravity or what pushed them in the first place?

lots of questions,please fill my head with your knowledge

[edit on 12-8-2005 by BZ]

Originally posted by BZ
there was supposed to be a light show in the sky last night over the uk,from a comet(cant remeber its weird name!).

They're called the Perseids, and they're from remnants of Comet Swift-Tuttle.

it was cloudy and late so went to bed and didnt see anything

It was cloudy here as well. I was pretty bummed.

got me thinking anyway.

That's great! Not too many people seem to do that anymore!

how come comets seem to just go around space?is it just due to gravity from the planets pulling in a big orbit?

They do orbit the Sun, and yes it's because of gravity. The planets, especially the larger ones do have some effect on comets as well.

how far have comets been tracked to? if theyre flying around all the distance they do surely they pick up some space dust far out there.

We know comets mainly originate from the Kuiper Belt and Oort Cloud. The Kuiper Belt is generally recognized as the area from Neptune's orbit, 30 AU, to about 50 AU and, for the most part, stays in the plane of the Solar System. The Oort Cloud is MUCH bigger; it extends out to about 3 ly away from the Sun in a spherical pattern. This is where most comets come from. The way they get pushed into the Inner Solar System is usually by gravitational forces from other stars or shockwaves from supernovae.

Keep in mind though, that the Oort cloud extends out 3 ly. The nearest star to our Sun, Proxima Centauri, is about 4 ly away. If it has an Oort clou similar to our Sun's there is a slight possibility that some comets could be from another star system!

That is why there is all the ineterest in them, just as you said "surely they pick up some space dust far out there."

also if theyre made of ice, where did the ice come from,i know its cold up there but it was made somewhere,also i dont know much about space but,in a gravity less and frictionless enviroment a small push on an object would see it carry on at that speed for infinity? what makes comets fly at these high speeds,gravity or what pushed them in the first place?

Well we're not entirely sure how comets form, other than perhaps being leftovers of planets. Also, ice doesn't neccessarily mean water ice. Comets are frozen gasses, normal hydrogen, oxygen, methane, carbon dioxide, and dozens of others. Yes, there is some water ice, but not all that much.

As I said above, what gets comets moving is usual gravitational interactment from a nearby star or from shockwaves caused by supernovae. Once a comet gets moving towards the Sun, the Sun's gravity sucks it in more and more, causing it to speed up more and more.

Hope that that helps.

EDIT: Forgot to mention that 1 AU is equal to the average distance of the Earth and Sun. So 30 AU would be 30 times farther away from the Sun than the Earth is.

[edit on 8/12/2005 by cmdrkeenkid]

* Me Dances around...I woke up at 4am and went outside, what a lovely clear night it was, the stars had an extra sparkle and they just blanketed the sky..made me feel alive again

Anyhows I got to see quite a few while I was out there. Towards the south west of Australia.... it was special..... and I felt all special to experience it.

They were lovely bright orange and burnt a fair way before trailing off, they left big streaks across the sky...I wish I could play the video of my memory of the event for you....but at least I can replay the streaks shooting across the sky to myself whenever I like now that I was there watching......

Mars is very bright too...


sigh I love our night sky ..... it makes me feel we couldn't possibly be all alone down here

[edit on 12-8-2005 by Mayet]

cmdrkeenkid did a pretty good job of explaining everything; I just wanted to elaborate a little bit because I like splitting hairs on technicalities

Originally posted by BZ
i dont know much about space but,in a gravity less and frictionless enviroment a small push on an object would see it carry on at that speed for infinity?

Your assumption is correct; in an environment completely void of any external interaction, it would carry on perfectly fine for ever. However, even the most empty regions of space aren't void of external forces. Although it's extremely miniscule, there's always gravitational pull from something.

Right now, you're technically being pulled in all directions by every object that has mass every where in the universe. Fortunately, however, the vast majority of those objects are so small or so far away that the gravitational attraction they have on you is virtually negligible. So an object floating in space will, over billions and billions of years, start moving towards the nearest larger object no matter how far away that may be. Although friction isn't quite a hinderance in space (to my knowledge at least), eventually that object that got pushed will start speeding up, slowing down, or changing direction.

Hope that makes sense; and if I'm wrong then I'd appreciate the correction.

thanks for the answers i think its all been covered.

im sure there plenty of habitable planets out there in various stages of evolution,just gotta wait for the clever ones to notice us