I was just studying meteorology and had a doubt about the motion of meteors towards earth.

Can a meteor be stopped while it is still under under the gravitational influence of Earth? As far as I know some meteors are very bulky and their motion towards the Earth's surface is with a huge magnitude of momentum. Has any organisation made any equipment to stop these meteors?

  • $\begingroup$ What do you mean with "under the gravitational influence of Earth". The stars in Andromeda is affected by Earths gravity, although not enough that we could messure it, even if we traveled to them. The effect of Earths gravity produces small, but measurable differences in the orbits of the other planets. If you mean when the meteor is within Earths sphere of influence, ie. the region of space where Earth provides the dominating gravitational pull, the answer is no, no one can. And no one is planning on getting the capacity, we rely instead on better detection. $\endgroup$ – Taemyr Jun 30 '14 at 10:56
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    $\begingroup$ Do you actually mean you were studying meteorology (i.e. weather), or were you studying meteors and related objects? $\endgroup$ – David Z Jun 30 '14 at 13:28
  • $\begingroup$ first I was studying meteorology and then jumped to meteors $\endgroup$ – romaan Jun 30 '14 at 18:48
  • $\begingroup$ Concerning terminology, see also this Phys.SE post. $\endgroup$ – Qmechanic Jun 30 '14 at 19:41

As of right now we have no way of deflecting an asteroid on its way to hitting the Earth. However there are lots of organisations tasked with looking into the issue. The Wikipedia article on Asteroid impact avoidance would be a good place to start. Also see the NASA Near Earth Orbit site for lots more background.

You are quite correct than the kinetic energy of an asteroid comparable to the one that wiped out the dinosaurs is enormous, and we have no chance of stopping it directly. However if we spot the asteroid early enough we can try and push it sideways to change its orbit. On the scale of the Solar System the Earth is a very small target, so if you can change the orbit of an asteroid by even a small amount that may be enough to make it miss the Earth.

Response to comment:

If by:

Can a meteor be stopped while it is still under under the gravitational influence of Earth?

you mean in the final stages of the asteroid's approach to Earth, then no if we leave it that late we are all doomed to follow the dinosaurs. If you allow a more liberal interpretation, note that many near Earth objects will fly by the Earth several times before eventually hitting it. On each flyby the Earth's gravity changes the orbit a bit until finally the change results in an impact. We might be able to deflect the asteroid during a flyby and make a big enough change to stop it hitting the Earth in the future.

It's hard to predict the orbit of an asteroid more than a few orbits in advance, because even tiny effects can add up to large changes in the orbit. So while we could possibly avoid an impact predicted for the next flyby, or the one after that, it's hard to be sure what would happen to the asteroid in the far distant future. Hopefully if we can gain a century or two our technology will have advanced enough in that time to make the next potential impact easier to deal with.

  • $\begingroup$ can you please answer the question keeping my point of in the influence of gravity in mind $\endgroup$ – romaan Jun 30 '14 at 10:42
  • $\begingroup$ cant this happen that after deflecting the meteorite it would travel a spiral path and again hit eart after a long time [usually millions of years of time] $\endgroup$ – romaan Jun 30 '14 at 10:53
  • $\begingroup$ @romaan: have a look now ... $\endgroup$ – John Rennie Jun 30 '14 at 10:57
  • $\begingroup$ thanks a lot for that answer john i am totally impressed by your answer thankyou verymuch $\endgroup$ – romaan Jun 30 '14 at 10:59

Two terminology issues first.

First, cosmology is the study of how the universe began and what will ultimately happen to it. Pieces of rock in our solar system have nothing to do with cosmology.

Second, a meteoroid is a small solid body in the solar system. A meteor is what we call such a body while it is falling through our atmosphere, usually glowing hot (e.g. a "shooting star"). When it hits the ground, whatever is left is called a meteorite.

Now to answer the underlying question. You have to understand that meteoroids come in every size from grains of sand to kilometers across. If something on the large end were headed toward us, there is little we could do without advanced preparation. That said, the larger the rock, the easier it is to detect, and thus the more warning we might hope to have. Gently pushing on a meteoroid for a long time can change it's orbit plenty in order to avoid hitting the Earth. There's no reason you would try to stop it's motion entirely; just nudge it out of the way. And for smaller objects, they will simply burn up in the atmosphere.

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    $\begingroup$ would you mofify your answer keeping my point in the influence of gravity into context $\endgroup$ – romaan Jun 30 '14 at 10:37
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    $\begingroup$ It's not just that more times allows for longer time to accelerate. More time also give the accelaration more time to take effect, a modest 1m/s of velocity becomes almost 5 times the earth radius of displacement after one year. $\endgroup$ – Taemyr Jun 30 '14 at 10:51

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