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Meteorites and Sonic Booms


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Hi Guys-

Has anyone ever heard of a meteorite fall (observed or unobserved) without hearing a sonic boom? I've read about cases where meteorites have been found in the morning that weren't there the day before - yet no one ever heard of or saw anything the previous night . To me, it would seem impossible for something to come in with such a high velocity and yet not make any noise whatsoever. Any opinions?

Steve

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Steve when I visualize certain trajectory angles, I can imagine and believe I have witnessed a fall that was so horizontal it seemed to almost follow the land curvature as I was viewing it.

That said imagine one comes in a long ways away makes its boom so far away you can't hear it but yet by the time it travels and reaches your area you can see it comming in and passing by for impact some distance away from you.

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Hi Guys-

Has anyone ever heard of a meteorite fall (observed or unobserved) without hearing a sonic boom? I've read about cases where meteorites have been found in the morning that weren't there the day before - yet no one ever heard of or saw anything the previous night . To me, it would seem impossible for something to come in with such a high velocity and yet not make any noise whatsoever. Any opinions?

Steve

for one try brodie spaulding, noblesville fall:

http://ares.jsc.nasa.gov/Education/Activities/ExpMetMys/..%5C..%5CSlideSets/ExpMetMys/Slides1-9.htm

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G'Day Steve

Light and sound is associated with meteoroids. The incandescent side can be seen over a wide area hundreds of miles from it's resting place, if it survives entry at 26 mps. Shock waves accompaniment is only apparent to people within 25 - 30 miles from it's final resting point as a meteorite.

Other factors to take into consideration. Isolation, one that comes to mind is 2008 TC3. This was spectacular in many ways. It was the first asteroid to actually be picked up and tracked. Big kudos to Richard Kowalski from the Catalina Sky Survey. A 1.5 meter telescope at Mount Lemon in Tucson Arizona. The following day, it exploded about 37km over the predicted location in the Nubian Desert, covering a very wide area 28km x 5km.

No one heard the sonic booms nor did anybody see electrophonic disturbances. This was very remote thus asteroid 2008 TC3 became Almahata Sitta an Achrondite, anomolyous polymict urelite. And it's still under investigation. It's proving to be a real rubble pile of fascinating stardust.

Almahata Sitta

Cheers

Johnno

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Steve when I visualize certain trajectory angles, I can imagine and believe I have witnessed a fall that was so horizontal it seemed to almost follow the land curvature as I was viewing it.

That said imagine one comes in a long ways away makes its boom so far away you can't hear it but yet by the time it travels and reaches your area you can see it comming in and passing by for impact some distance away from you.

Hi Frank-

That would make sense but I keep thinking about some recent cases where meteorites went through the roof of a building and were recovered. One of the cases was on the east coast involved a dentist office and can't remember where the other one was. In either case- I don't recall anyone hearing anything until they went through the roofs. I do believe they were both observed but no sonic booms or other sounds were made to my recollection. I find it hard to believe a meteorite traveling horizontally could penetrate a roof. Must be some other factors involved also.

Steve

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Hi Frank-

That would make sense but I keep thinking about some recent cases where meteorites went through the roof of a building and were recovered. One of the cases was on the east coast involved a dentist office and can't remember where the other one was. In either case- I don't recall anyone hearing anything until they went through the roofs. I do believe they were both observed but no sonic booms or other sounds were made to my recollection. I find it hard to believe a meteorite traveling horizontally could penetrate a roof. Must be some other factors involved also.

Steve

Very generally most of the meteorites that penetrate roofs, cars, etc., are larger stones, over 1lb. A stone weighing that much doesn't have to be exceeding the speed of sound to penetrate something as relatively weak as a wooden roof or piece of sheet metal on a car. Hailstones actually do it regularly.

Most meteoroids enter at great speed, begin slowing with atmospheric friction, heat up and break apart far in the atmosphere, making a spectacular flare, but inaudible to us on the ground. It's the rare ones that make a spectacular fall, exploding at lower altitudes where their explosion can be heard. The pieces all will fall to Earth very slowly, and are cool to the touch when they hit. Seldom will those pieces break the sound barrier, producing a sonic boom. Most of the noise heard is the break up of the meteorite, and as has been mentioned you have to be very close to hear that. The rarest are those that don't come apart, and make an impact crater when they hit. Again, you'd need to be relatively close to hear it.

Disclaimer: I'm relatively new to meteorites, but the foregoing is what I have learned thus far. Anyone with better info, feel free to jump in here and clarify/correct my post.

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