Some people say "if meteor will hit earth, we will destroy the meteor by nuclear weapon."

But I guess nuclear weapon can't destroy a meteor. If so, nuclear weapon made a large crater on earth when bursted in surface. Nuclear weapon can little destroy rock.

Better way for avoiding to hit meteor is to put rocket on the meteor. The meteor would be deflected from orbit of earth by the rocket, thus, we will avoid the crisis.

Humans are going to have to deal with it sooner or later.

Most of the articles say attempting to destroy a meteor is a very bad idea. Indeed the general consensus is best to change its trajectory.

Well I think we shouldnt worry about it for a number of reasons.
1.Chances are we wont see it until its too late.
2.Even if the Authorities do find it,theres a fair chance theyll hush it up as long as possable,to avoid panic.

Maybe it'll have a little blob of red jelly-like stuff inside and after it hits the earth, it'll start moving and devouring everything in sight and getting bigger and bigger and bigger and finally cover a small diner where some good folks are holed up in the basement and...

Oh wait.

Nevermind.

We know the majority of asteroids that are in similar orbits to Earth. If a rogue asteroid came in and knocked one of those others off orbit onto a collision course with Earth, the chances are that it would not hit Earth for a few years. With a nuke, we could hit the asteroid to change it's orbit a tiny amount, but given the large range of the orbit around the sun just blasting the asteroid a fraction of an inch will result in hundreds or thousands of miles of change by the time it would have hit the earth. I doubt we are in any danger of being severely damaged by an asteroid.

The danger is not that great from an asteroid we know about. We could do something about an asteroid we know about well in advance, although it would be expensive. Not as expensive as an asteroid hitting the earth, but costly nonetheless. The good publicity would undoubtedly outweigh the expense for the nation doing it. It could wind up being a race to accomplish it between several nations.
The possibility of unknown asteroids hitting the earth is an unknown. We don't know how many asteroids in potentially dangerous orbits we don't know about. Not that long ago a good sized chunk of rock passed between the moon and earth, and was only discovered as it was leaving the vicinity. It only takes one asteroid hit to ruin the whole earth's day. Interestingly, funding has been cut to continue surveying for such asteroids, because the money is needed for other priorities such as the continuing war in Iraq.

'ruin the whole Earths day'understatement of the century,haha.

Well I think we shouldnt worry about it for a number of reasons.
1.Chances are we wont see it until its too late.
2.Even if the Authorities do find it,theres a fair chance theyll hush it up as long as possable,to avoid panic.
There will be some who will panic, but most people will turn stoic.

I think within a decade we will have the ability to detect well in advance any asteroid that is a threat a good century before the fact. The odds are extremely large there will be no threats for many thousands of years. If one is found, there will be plenty of time to nudge its obit a few tenths of a meter--enough to avoid problems.

Comets are slightly more dangerous. Those in known orbits can be dealt with like meteors, and a new comet coming in from most possible trajectories would be detected about two years before collision. This is less time, and comets are more difficult objects, but I think mankind would save itself. Maybe not today but the ability will be present within our lifetimes.

Just a technical side note for anyone who cares:

A meteoroid is a piece of rock in space, ranging from a pebble to a large boulder in size.

A meteor is a meteoroid that enters our atmosphere.

A meteorite is the remains of a meteor after it hits the Earth.

An asteroid is composed of mainly metals and rock and they are large enough that they are often called minor planets. These are the planet killers.

A comet is composed mainly of ice and rock and can range greatly in size, though they tend to drastically decrease in size when they come closer to the sun as the ice melts off.

To add a little to your definitions, again, in case anyone cares,

The term "meteoroid" is rarely used in the astronomical literature; "small asteroid," or just "rock" are more common. (Even smaller objects are "space pebbles" and even smaller are "dust").

Asteroids originate in the "asteroid belt"--they sometimes get into orbits outside that belt because of collisions or planetary perturbations of their obit. A few space rocks come from the Moon or even other planets when bits are knocked into space by stuff hitting them.

Comets come from outside the orbits of the planets--the Oort cloud and the Kuiper belt.

http://www.nineplanets.org/kboc.html

The reason asteroids are "rocky" while comets are "icy" derives from where in the solar sytem, relative to the sun, they formed. The asteroids formed closer in where volatile gasses tended to be blown away from small objects. Comets formed far further out where it was so cold this had no effect.

Comets crossing the Earth's orbit are far rarer than asteroids that do so, but they would be more dangerous if they weren't so rare, since a "new" comet that happened to be aimed dead on at the earth (an extremely remote possibility) would not be detected until a year or so in advance.

We have the technology, if we would use it, to detect any dangerous asteroid.

What technology is that.

Radar. http://neo.jpl.nasa.gov/news/news141.html

There u see u guys have me paranoid now. Theres an extremely bright star out to the NW which I didnt notice last nite.

Radar. http://neo.jpl.nasa.gov/news/news141.html
Fascinating article--thanks.

What I had in mind (and radar would certainly supplement this) is the ongoing automated search for asteroids using a number of telescopes and automated blinkers. (A photo of the same part of space is taken twice, a few minutes apart, and then the two pictures are compared by a computer to see if anything in it moved--distant objects will seem stationary but close-in objects--such as asteroids--will move).

Once such an object is found, further pictures are taken to determine its orbit--and such orbits can then predict where it will be out hundreds of years.

I guess that we need rader-picket satellite for searching meteor.
Especially, for on the other side of Earth on the orbit.