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Asteroid on Course to Earth Was Spotted Just Hours Before It Hit The Atmosphere
Witnesses reported a fireball streaking across the sky above Botswana on Saturday night. The asteroid hurtling toward Earth at 10 miles (16 km) a second looked like it could be the harbinger of catastrophe. A webcam in a rural area west of Johannesburg captured it, showing a luminous orb igniting the sky in a bright flash.
NASA had only discovered the asteroid on Saturday and determined it was on a collision course for the planet, charted for entry in a vast expanse from Southern Africa and across the Indian Ocean to New Guinea and given the name 2018 LA.
The reality of the asteroid's fiery end was less dramatic than the video shows. The asteroid was estimated at just six feet (1.8 metres) across, otherwise known as boulder-sized, NASA's Jet Propulsion Laboratory said in a statement. It burned up "several miles" above the Earth's surface.
2018 LA aka ZLAF9B2 (25-35 tons).
2014 AA (40 tons).
2008 TC3 (80 tons).
(Score: 2) by c0lo on Wednesday June 06 2018, @12:25PM (4 children)
I feel marginally better than in the Chelyabinsk case [wikipedia.org], but a window of less than 24h from discovery to impact is too close to "I discovered myself dead due to this bullet in my back".
Please do better next time, even when younger Bruce Willis needed more time to prepare.
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 1, Informative) by Anonymous Coward on Wednesday June 06 2018, @12:38PM (1 child)
uhm. I realize you're trolling, but there are people out there who will not, so please don't troll.
for everyone else: the more dangerous an asteroid is, the earlier it will be discovered, because it will be bigger.
my only assumption when stating this is that asteroids all have more or less the same density, which is not true, but still a reasonable approximation.
In other words: an asteroid made of solid iron (high density) that is big enough to really hurt us (the high density means that it wouldn't need to be very big) would still be seen quite early.
(Score: 2) by c0lo on Wednesday June 06 2018, @10:53PM
Really?
Note to myself: be more subtle next time.
True... Unless it won't, that is.
I mean, look, the Chelyabinsk one was larger than the ones linked in TFS.
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 0) by Anonymous Coward on Wednesday June 06 2018, @02:04PM (1 child)
The recent Chelyabinsk meteor actually did some damage, but in general only the smallest impactors are not going to have years of advance warning.
These interstellar asteroids could be a bigger problem. Unknown trajectories and sizes with higher velocities. It may be impossible to deflect them.
(Score: 2) by HiThere on Wednesday June 06 2018, @06:23PM
I think your certainty is unwarranted. It doesn't take that large an asteroid to do immense damage, and if they're dark enough, they are quite difficult to see.
We're certainly doing better about mapping asteroids than we were, but we are far from "nearly complete for anything large enough to matter". And ones we don't know about can come up on our "blind side", where they're nearly invisible until quite late. (Looking into the sun to resolve details is difficult.)
Of course, in addition to the color, the density is important. A chunk of loosely joined frozen methane could be quite large, and still not do any damage. A chunk of nickel-iron much smaller could be a lot more dangerous. And would be a lot harder to see. The Chicxulub impactor that closed the cretaceous period is guessed to have been between 5 and 10 miles in diameter. Something a quarter that size could probably do about 1/64th as much damage. OTOH, I don't know what they were assuming the composition of the impactor was. Analog once did an article ("Giant Meteor Impact", IIRC) about an impact by a metal meteor 5 miles in diameter that seemed to be even worse...but the assumptions were "back of envelope" calculations, so they could be wrong.
Still, even something 2 miles in diameter would probably be a civilization ending disaster. 1 mile would be a disaster worse than any in history. etc. And as you get smaller, there are LOTS more. Fortunately, space is big enough that we're a small target, and nothing's really aiming at us. But don't be certain that we know about anything that could cause a problem. Even if we do, asteroid orbits get altered all the time when we aren't watching.
It's not a major danger, but it's nothing to feel certain about, either. It's not at all unreasonable to wish for a better job of mapping. (IIRC, just this year something that had been classified as a star turned out to be an asteroid. And just last year they lost track of one that was of significant size. They thought (in the article that I read) that its orbit had been altered, but they didn't know what it was now. If they find it again, they won't know it was the same one.)
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