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Comet question(s)...
the_exile
Kupo!
in Zocalo v2.0
These questions aren't really about comets, but if I told you what it's really about, I'd have to kill you. :)
1) What is the difference between a meteor, and asteroid, and a comet? I think it has something to do with comets being bigger and coming from the Oort Cloud, but that's about the extent of my knowledge. Oh, and for the love of your Chosen Diety, pleeeeeease don't pull any meteor-wrong jokes.
2) Scientists track 'em by their tails, right? Do they have any other means of tracking them? Say a... I don't know, 400-km wide behemoth came hurtling at Earth, leaving no trail or anything; just a big, black Thing. How long would it take us to notice it/how long of an advance warning would we have? And how would we notice it? Lack of stars where they should be? Anything else?
Perhaps more in the future, when you've answered these two. It's for a writing project I'm working on... I think Sean knows what I'm talking about, assuming I didn't bore him to death. :p
1) What is the difference between a meteor, and asteroid, and a comet? I think it has something to do with comets being bigger and coming from the Oort Cloud, but that's about the extent of my knowledge. Oh, and for the love of your Chosen Diety, pleeeeeease don't pull any meteor-wrong jokes.
2) Scientists track 'em by their tails, right? Do they have any other means of tracking them? Say a... I don't know, 400-km wide behemoth came hurtling at Earth, leaving no trail or anything; just a big, black Thing. How long would it take us to notice it/how long of an advance warning would we have? And how would we notice it? Lack of stars where they should be? Anything else?
Perhaps more in the future, when you've answered these two. It's for a writing project I'm working on... I think Sean knows what I'm talking about, assuming I didn't bore him to death. :p
Comments
An asteroid, on the other hand, is a large chunk of rock. It doesn't have to orbit the sun at a regular period.
A meteor is a piece of matter falling through an atmosphere.
For tracking, they typically use a photo comparison method (or used to, they might have something new now) where two photos are taken a certain time apart and compared for objects that have moved. You can also do it by taking a time-lapse photo with a camera that compensates for the Earth's rotation, then looking for streaks.
"Say, what's that big black bob in the sky that's surrounded by flames? It's getting bigger too..."
radar or lidar could catch things not in the visible range...
The bigger question is why we don't spend a lot damn more money on it...
:(
[B]There would be several million spottings. Easy.
"Say, what's that big black bob in the sky that's surrounded by flames? It's getting bigger too..." [/B][/QUOTE]
You'd be surprised at how often that *isn't* the case...
[B]There would be several million spottings. Easy.
"Say, what's that big black bob in the sky that's surrounded by flames? It's getting bigger too..." [/B][/QUOTE]
Well from thousands or millions of miles away, it's not a big, flaming blob.
1) The differance between a commet and the other two is that a commet will emit gasses and other things (forming the head and tail we are familar with). Asterioids and metiors do not. I have heard two definitions between the two: The first is the size. I am not sure of the cut off between an asterioud and meteor. The other def I have heard is that asterioids have well defined orbits, while meteors do not. (Meteors are also the bi-products of comets).
2) Comets can also be tracked using other methods. Even though they may nto have a head to them, they still reflect light. Asteriods and meteors are done the same way. Otherwise we would never know they existed! Also (from my understanding) commets develop thier head between jup and saturn as well, making them more easy to detect.
BTW we have a commet coming by this spring, it looks like its a new one so it will either be very cool or a big dud.
[B]I don't know the technical difference, but my guess would be that a comet is defined as being a large proportion of ice that orbits the sun at a regular period.[/B][/QUOTE]Nucleus of a comet is like dirty snowball:
It consists: dust, pieces off rock and ice and other volatile materials which forms coma and tail. (which can be millions of kilometres long)
Comets have also highly elliptical orbits.
[url]http://en2.wikipedia.org/wiki/Comet[/url]
[QUOTE][B]An asteroid, on the other hand, is a large chunk of rock. It doesn't have to orbit the sun at a regular period.[/B][/QUOTE]
Line between between asteroid and comet is also inexact.
Everytime comet visits near sun it loses its material so in some point there is nothing to vaporize and nucleus becames like asteroid with highly elliptical orbits.
There are many asteroids with orbits like short period comets and which are propably old comets nucleus. Many of these are also NEOs (Near Earth Objects) whose orbits cut earth orbit and could someday collide with earth. ([url]http://en2.wikipedia.org/wiki/Apollo_asteroid[/url])
Biggest part of asteroids have stable orbits and lies in asteroid belt between Mars and Jupiter. (in place of one planet: [url]http://www.mira.org/fts0/planets/091/text/txt001x.htm[/url], [url]http://en2.wikipedia.org/wiki/Titius-Bode_law[/url])
[url]http://en2.wikipedia.org/wiki/Asteroid[/url]
[QUOTE][B]A meteor is a piece of matter falling through an atmosphere.[/B][/QUOTE]
Other name for meteor is shooting star.
Those particles that cause meteors (or shooting stars) are called meteoroids and have size from small piece of rocks to dust particles.
Meteoroids which survives through atmosphere are called meteorites.
(those can look even like this: [url]http://koti.mbnet.fi/tuunaes/Space2003/meteorite.jpg[/url])
Use these to find more:
[url]http://www.wikipedia.org/[/url]
[url]http://scienceworld.wolfram.com/astronomy/letters/[/url]
[B]It is scary to think that most observations of potentially dangerous objects are done by visual light comparison.
radar or lidar could catch things not in the visible range...
The bigger question is why we don't spend a lot damn more money on it...:( [/B][/QUOTE]
It's because getting people to fight against each other is much more profitable. (at least to someone)
And that's also one way leaders can stay in power. (people might not like the leader but when there's an "enemy" leader can use it to get support from people and stay in power)
Comets: Have elliptical orbits around the sun.
Asteroid: Have round orbits around the sun.
Meteor: An asteroid within the Earths atmosphere.
This is what I have surmised after several Astronomy classes. These definitions also imply some things, i.e. comets are only seen at a close distance to the Sun, when they begin to evaporate etc., but these are the simplest definitions.
I suppose I'm an idiot to not think that light would reflect off of said Thing (NOT NECASSARILY A SPACE ROCK) anyways, but... whatever. There's always the possibility that it's wearing Space Camo. :D
It's not exactly a major point in the story, anyways.