The Astronomy Thread

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Pancreas

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Meteors do not have to be shot down in order for them to break up in the atmosphere.

As for what would be harder to shoot down... the meteor by far is the harder target. Not because of it's speed or trajectory, but simply because of where our information gathering technology is based and focused. We have far more stations equipped with radar to detect flying aircraft then we do with sensors and telescopes to find bits of rocky debris hurtling through space.

If we really were interested in blowing up meteors before they hit the earth we would need more satellites, telescopes and probes out there sniffing for potential threats. These objects are notoriously hard to spot as they emit no energy and it is only the light cast from the sun against one side that allows us to detect them. They are minute in size and travelling damn fast. Some of them get caught up in earth's gravity for prolonged periods of time, like months or years. It is crazy the amount of stuff that is zipping around us all the time. Thankfully space is rather huge and our atmosphere does an amazing job of burning things to a crisp.

I wouldn't suggest shooting anything down before it enters our atmosphere anyways. If we actually managed to nuke something and blast it into tiny pieces, chances are the earth would end up attracting all of the debris and probably get clogged with bits of floating rock trapped in close orbits. This would make any further launches into space very difficult to say the least.

Years ago I saw a special that was talking about nudging potentially dangerous asteroids off course using probes that would land on the surface and then ignite some engines. It wouldn't have to be very powerful if given enough time to operate. Just enough to change course a fraction of a degree maybe.

Anyways this meteor in Russia was damn cool if not a little scary. The thing landed in a lake, and they also found a 20 foot crater near the shore line... It was probably just some debris from when it broke up, but I like to think the thing skipped once or twice before going under.
 

Furry

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It came in at a steep trajectory with a relative speed probably in the 40-50thousand+ mph range. It would of been impossible to shoot down for any modern system.
 

Lambourne

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Even if you could blow up a meteor you'd still end up with dozens of chunks of rock falling to the Earth, which is pretty much exactly what happens when you don't shoot it. Most of the damage and injuries were from the shockwave which you can't do anything about once it's entered the atmosphere. Only real way to do anything about these is to deflect them away from Earth in space.

Astronomer Phil Plait's take based on what we know now:
source
Around 09:30 local time, a huge meteor came in over western Russia. The trail it left in the sky was 320 kilometers (200 miles) long, it shone as brightly as the Sun, and the shock wave of its passage through the air blew out windows, sending glass flying and injuring (at last report) nearly a thousand people. It was caught on hundreds of videos in some of the most dramatic footage of any event I?ve ever seen. The shots of the trail it left in the sky alone are jaw-dropping.

As a quick aside, the direction and timing of this event make it very clear it was not related to the passage of 2012 DA14 today. This is a coincidence. An amazing one, but I?ll note that asteroids around this size enter Earth?s atmosphere fairly often, every few months or years, usually in remote areas (we?re 70% ocean, and most land area on Earth is far form cities).

So what happened to the meteoroid, the actual solid chunk of matter that did all this? There are now reports that at least one sizeable piece landed in Chebarkul lake a few kilometers west of Chelyabinsk, Russia. The lake was frozen, and a large hole, nearly 10 meters (33 feet) across, was found in its surface.

I always try to be skeptical about such things, but this looks legit. Pictures show small, dark chunks of what look like rocks around the hole, which is to be expected if a piece of an asteroid broke up and fell. The ice is pretty thick there (it?s Russia in the winter, folks) so faking this would be quite an effort.

So what do we make of this? I?ll speculate a bit here based on what we know of this particular event, plus what we know from previous such incidents.

The incoming rock was probably in the size range of a few meters in diameter. The split in the trail high in the air indicates the rock itself broke up as it rammed through our air at dozens of times the speed of sound, probably still (at a guess) 20 kilometers (12 miles) above the ground. It heated up violently, getting very bright and decelerating savagely. It went from many times the speed of sound to subsonic speeds in just a few seconds. It would?ve broken up into many pieces at this time. That would explain the multiple sonic booms heard in various videos.

After a few seconds, it slowed enough that it was no longer quite as hot?most of the molten parts would slough off by the meteoroid?s rapid motion through the air. Over the next few minutes it fell at several hundred kilometers per hour?about as fast as an airplane?through the upper atmosphere. It?s cold up there, and the material was only hot for a few seconds, so most of the pieces would no longer even be warm. There would be even more breakup as the rocks continued to slow due to drag, some bigger than others, and they would start to separate.

By the time they hit the ground, smaller pieces were moving at terminal velocity, maybe a couple of hundred kilometers per hour, some less?faster than a car on the highway, but not super-fast as most people might think. I?m not sure what this means for the size of the object that plunged into the lake. It must have been decent-sized to make a hole that big. However, I?m not sure how much the ice would break up upon and after impact. It was smaller than the hole, but by how much? I wouldn?t be surprised if it were over a meter across, though.

I expect that a lot of fragments from this meteor will be found. They?ll also be very valuable. Scientifically, for obvious reasons, but also because we have more than enough data on this rock to establish what orbit it had before it hit us. Having physical samples to study together with info on where it was in space is invaluable for learning more about the asteroid population in the inner solar system.

But also, having fragments from a known fall?and one with so much amazing footage and drama?means collectors will be all over this. I collect meteorites myself, and I feel a pretty good pang of envy toward anyone who can manage to (legally!) obtain chunks of this. I?d love to have one on my shelf.

There is still a lot we can glean from this event, but I suspect the best, and most lasting, lesson will be that the Universe is not necessarily friendly. It reminds of this sometimes, and we need to take that threat seriously. That this comes within hours of the passing of 2012 DA14 is actually a solid jolt that should make people sit up and take notice.
 

Tuco

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Eomer

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Pancreas_sl said:
As for what would be harder to shoot down... the meteor by far is the harder target. Not because of it's speed or trajectory, but simply because of where our information gathering technology is based and focused. We have far more stations equipped with radar to detect flying aircraft then we do with sensors and telescopes to find bits of rocky debris hurtling through space.
Yes, it's mostly because of speed and trajectory. Even if you could detect them well in advance, they're flying at ridiculous speeds and altitudes. The only way a missile could have intercepted this after it entered the atmosphere (for zero reason, mind you) would be if it was based and launched from the perfect position downfield of it's trajectory. Even the PAC-3 has a maximum altitude of about 70,000 feet and speed of Mach 5. This fucker was moving at Mach 20-30, at well over 100,000 feet. Even ABM systems aren't capable of catching that kind of an object unless it's flying towards them:

http://en.wikipedia.org/wiki/RIM-161...d_missile_SM-3

http://en.wikipedia.org/wiki/Termina...e_Area_Defense

Blowing it up while it's still in deep space? That's a completely different story. It's something that's never been attempted. Even landing on it and trying to nudge it's orbit is outside of known technology. Only in the past decade have a couple asteroids been landed on, and the Japanese one if I recall was a clusterfuck. I'm not saying it can't be done, I'm saying that no current technology can do it.
 

Fuse

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Blowing it up while it's still in deep space? That's a completely different story. It's something that's never been attempted. Even landing on it and trying to nudge it's orbit is outside of known technology. Only in the past decade have a couple asteroids been landed on, and the Japanese one if I recall was a clusterfuck. I'm not saying it can't be done, I'm saying that no current technology can do it.
Bullshit. I saw a documentary about that. I think it was called The Abyss.
 

Lenas

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Even if you could blow up a meteor you'd still end up with dozens of chunks of rock falling to the Earth, which is pretty much exactly what happens when you don't shoot it.
Well ideally they'd aim to blow it up while still outside of the atmosphere so the remnants would burn up completely during entry.
 

Pancreas

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Oh I didn't mean to make it sound like any impact prevention was evenly remotely possible right now. Anything regarding interception or course correction is pure speculation. And my other point was that the largest part of the issue with trying to tackle one of these is that currently we almost never detect them until those last few dramatic seconds before impact. No matter what it is you are shooting at, if you can't see it, chances are you can't hit it.
 

Troll_sl

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Blowing it up while it's still in deep space? That's a completely different story. It's something that's never been attempted. Even landing on it and trying to nudge it's orbit is outside of known technology. Only in the past decade have a couple asteroids been landed on, and the Japanese one if I recall was a clusterfuck. I'm not saying it can't be done, I'm saying that no current technology can do it.
It's not "outside of known technology." That's a retarded thing to say. We know how to do it. We just haven't put any resources into realizing the process.
 

Disp_sl

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I was camping in the Sierra Nevadas about 7 years ago with some friends when a meteor passed by just like this. It was about 1 AM and all of a sudden the whole sky lit up for a few seconds and then we heard a huge boom. Craziest thing I've ever witnessed.

Thanks for reading. I have a newsletter too.
 

Big Phoenix

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Ignoring the trolol, I think you guys are forgetting;

1. Its made of solid rock

2. The amount of explosives carried by any SAM are negligible

Combine those two facts and realize any SAM would do absolutely nothing to a 10m size meteor.
 

TheBeagle

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A lot of overestimation of technological capability in this thread. It's not like they knew this thing was coming and had jets scrambled in just the right spot. It also wasn't exactly in a spot that's going to need tons of SAMs or any kind of ICBM missile defenses...its in the middle of not much. I'm pretty sure all that stuff is mostly 1500+ miles to the west. Jets and missiles aren't magic.
 

Julian The Apostate

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Why do all the new articles I see keep calling the explosion a sonic boom? The explosion had nothing to do with a sonic boom caused by a object traveling over the speed of sound. It was the fucking meteor entering the atmosphere, heating up, and blowing the fuck up. Nothing to do with a "sonic boom".