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Paul - difficult to say for certain but what you describe does sound like a meteor, or what's normally described as a fireball or bolide. The latter are meteors but instead of being a small speck of dust entering the atmosphere they are small rocks. They leave a trail and explode high up in the atmosphere due to ram pressure - this is what happened to the Russian meteor although in this case it was a few thousand tons of rock, not a small boulder! Essentially what happens is that the meteor compresses the atmosphere immediately in front of it causing the meteor to experience very high pressures, especially as the atmosphere gets thicker as it gets closer to the ground. At some point the pressure exceeds the structural strength of the meteor which breaks up violently. The energy released goes into the immediate atmosphere and surviving rock as heat hence the flash (and noise).
It's rare to actually hear these things, even big ones, but does happen. In this case the meteor broke up right above a city and because of its mass and velocity the energy released into the atmosphere (and windows in the streets below!) was the equivalent of a few hundred kilotons of TNT - several times larger than the atomic bombs dropped on Japan in WWII. The meteor exploded several miles above the city but a bang like that would clearly have been heard there. If you were a few miles away you might not have heard it although certainly would have seen it!
Fireballs/bolides happen all the time. They are spectacular when you see one (I've seen three or four in my lifetime) but usually are much smaller than the Russian one and you'd likely never hear the explosion, even if you were nearby. There are also cases where a rock skims the upper atmosphere. It gets in far enough to leave a trail which can go on for thousands of miles but then essentially bounces off the atmosphere and returns to space. I think there are a couple of videos of events like this on youtube. Will try and find them if you're interested. Pog might have even seen something like this. Pog - did it burn up, disappear or what? Am curious to know.
And nothing as exciting as that to show you from my dash cam, Pog! Sorry.
Tom
http://apacificview.blogspot.com/
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I saw something several years ago while taking an outside shower in California. There was a streak in the sky and a flash that lasted a second or two. The entire landscape lit up as if it was midday, and then it abruptly extinguished. No sound at all. If I had been otherwise occupied inside the house, like watching TV, I probably wouldn't have noticed anything at all.
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Hunt - yep, that was almost certainly a fireball or bolide. The flash can be incredibly bright but as you describe is very short. It can appear to be as bright as the sun at least for someone relatively nearby. They happen a lot but clearly most of the planet isn't populated so most go unnoticed, and even in the populated areas these things would have to happen at night and have someone just by chance looking the right way, so you can understand why most go unreported.
While working at night on MK I've seen two or three just because I stepped outside to check conditions and used to spend a lot of time doing that because the view is so spectacular (we're talking nearly 20 years now), but never saw something as bright as you or Paul report, so you can imagine how most of these things are never seen. Some earth-monitoring satellites are now telling us how often these things actually occur, and it's much more common than you'd expect. Even the Russian meteor was caught by a satellite when it entered the atmosphere. Twenty years ago that would not have happened.
Tom
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Thanks for the info Tom, I didn't know that about meteors reaching a point where they explode due to the thickness of the atmosphere.
I read once (in a critique of a movie, I think) that meteorites aren't burning hot when they land. Do you know, is that true?
It would be great to be up at MK at night, I like to play spot-the-satellite when it's clear.
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Paul - that's actually correct. Small meteorites are not hot when they land. They are slowed down so much by the atmosphere that a few miles above sea level they almost stop and then fall to the ground under the influence of gravity. Small meteorites hit the ground at their terminal velocity which is typically three or four hundred mph rather than their cosmic velocity of 20-30 miles per second (probably obvious, but cosmic velocity is the speed they had before they entered the atmosphere). They might retain a little heat but certainly aren't glowing hot.
The limit is believed to be around 10 tons. Anything below that will not hurtle into the ground, it'll slow down and burn up or explode. Anything above that will also burn up but will retain some cosmic velocity. Big rocks, we're talking several hundred metres in diameter, will keep their cosmic velocity all the way into the ground. Not that they happen often, but you don't want to be anywhere near one of those. The dinosaurs found that out.
Tom
http://apacificview.blogspot.com/
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A compilation of why there are so many dashcams in Russia:
http://www.youtube.com/watch?v=ZPkE2hHneP4&feature=share
"It was a majority decision to descend into the Dark Ages. Don't worry, be happy, bang on da drum all day!"
*Japanese tourist on bus through Pahoa, "Is this still America?*
It looked pretty much like this tom
http://www.youtube.com/watch?v=VNtsVP42bOE
aloha,
pog
O.K. ... Somehow, I'm always the one who sees the Owl @ night when no one else does ... Cannot believe it was not reported on news but what I saw was a flaming something that lasted at least two seconds and just appeared, blazed over my head with a leading edge ball and then 'vanished' as quick as it came w/ No trail/tail after.
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Tough to say from your description, Pog, and that meteor in the movie had a trail (that movie was awful but the special effects were pretty awesome for the time!). Couple of extra questions that might help. Did you see it at night and which direction was it traveling relative to you, i.e., was it like the movie clip, did it head towards you or across your field of vision? Thanks!
I suspect you saw a bolide and it would have been many tens of miles above you (it might not have seemed it at the time) but I'm still a little confused about exactly what you saw.
Tom
http://apacificview.blogspot.com/
Tom, the movie link was ball busting .... Using that as a guide though, leading edge almost too fast to see but still spherical with an evaporating / ethereal tail ... Answers >>> Day time, North to south direction as parallel to my own direction of travel which was south to north @ 350 min / 360 max @ < 20mph.
aloha,
pog
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Pog =- thanks for the additional info. You almost certainly saw a bolide and/or fireball and quite a spectacular one. Since it was heading towards you it's unlikely you saw a trail. You would have seen one if the object was large (like the Russian one) but suspect this was small enough to create what's called a train but I hate that term. It's a trail of ionized molecules that quickly recover and given this was daylight you'll never have seen it. At night you might have seen that trail, at least for a few seconds.
If I'm right I'm not surprised it wasn't reported on the news. You might have been the only person to see it or at least one of very few people. Those things aren't tracked before they enter the atmosphere, there's no warning of them entering the atmosphere and only those who happen to be in the right place at the right time and also looking at the right place see them.
Count yourself as very fortunate to have seen something like that. Most people never will.
Tom
http://apacificview.blogspot.com/
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