If Earth was going to be hit by a huge asteroid how long would we see it coming?

Question

i.e. would we see it with the naked eye for days or weeks or not at all?

Answer 1

If something was to hit us it would only be visible with the naked eye as it tears through the atmosphere, minutes before impact. The likelyhood is that an asteroid of very great size would be spotted through telescopes years before it hits us. Scientist are studying near earth objects that might have the potentian of hitting us:
http://www.spaceweather.com/ (scroll down)
However, only 793 are know so far, while the total number is estimated at 2000.

Answer 2

Depends on where the asteroid is coming from and it's composition.

If your asteroid is a comet coming out from beyond the solar system it would be seen, a few weeks, before it impacted with the earth. If the asteroid is stone or nickel iron it's path could only be seen as it occludes the stars behind it. In that case the first naked eye sighting would be as it hit the atmosphere.

If the asteroid rounds the sun and heads towards earth from the sun side it won't be seen, with the naked eye, against the sun. A comet may just be visible as a smudge in the sky near the sun. It would be visible through "eclipse" telescopes.

On June 30 the earth will be passing through the beta taurid stream which are coming from the sun side. So have a look and see if you can see something then in the daylight sky.

Answer 3

The short answer is -- it depends. You would have to take into consideration the size of the object and the direction from which it originated. There are documented instances of many Near Earth Objects (NEOs) that have passed very close to Earth (in astronomical measurements) and went undetected until they were past us!

There are people who devote a great deal of time looking for these objects. You can find a link to NASA's Near Earth Object website below.

By the way -- a comet breaking up in Earth's atmosphere would do far more damage. Either way, it would not be a pleasant experience!

Answer 4

Asteroids generally offer decades or even centuries of warning -- unless they are too small to detect, in which case there is no warning at all. But today's technology enables astronomers to get a fix on any asteroid capable of causing a global "extinction event" -- six miles in diameter or bigger. The smaller ones may not be seen until a week, or days before impact

Answer 5

Our eyes are only capable of seeing a few lightyears into space; for example, we can sometimes see mars (though that's not several lightyears away - more like 78.39 * 10^6 kilometers) on a clear night. So if we were to start seeing the asteroid/meteor in the atmosphere, we probably wouldn't be able to escape in time. However, with the world's most powerful telescope (the Hubble space telescope), we would be able to see it coming from several billion lightyears away.

Answer 6

I would depend on the size of the asteroid as if you could see it or not and when. It would be observed through observation equipment long before seen with the naked eye.

Answer 7

With all of this technology today, we would see it in about 1-2 weeks

Answer 8

a few days back i received an email from a friend who forwarded me an information/illustration that earth will be hit by a massive asteriod by 2019...forgot the specific date. it showed an illustration supposedly released by nasa...dont know how true it was. but said information stated that we'll be back to the primitive times as billions of lives will be expected to be lost. hope its not true. but if ever...i think we'll see it coming for weeks just like comets as they pass near earth.

Answer 9

I think by the time you could see it with the naked eye, you'd be toast. But scientists will see it light years ahead and the gov't will keep them silent about it. Hopefullly someone is coming up with some contingency plans! :)

Answer 10

since an asteroid does not give off it's own light and reflects sunlight only, it is conceivable that it could track in the shadows of the moon and the earth to stike us unseen.