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View Full Version : Sonic Boom in CHCH



Hitech
12-09-2006, 05:07 PM
http://www.telstraclear.co.nz/newsfeed/news_item.cfm?id=108609

Read this link.

jermsie
12-09-2006, 05:10 PM
Quite amazing to hear a sonic boom from a meteor. I heard it thinking a petrol tank or something had exploded!

Thomas01
12-09-2006, 06:46 PM
Quite amazing to hear a sonic boom from a meteor. I heard it thinking a petrol tank or something had exploded!

Yes that was my first reaction - somebody locally had done something to a petrol tank or similar. It was a very large bang and apparently heard over a large area of the S.Island.

Space Junk ?
No way.
Man made space junk, and I am assuming that this is what the police mean, is in fact made as light as possible. Can you imagine the size of rocket needed to lift a large solid object able to produce this noise?

Zippity
12-09-2006, 07:17 PM
Can you imagine the size of rocket needed to lift a large solid object able to produce this noise?

I'm sorry.

I can't follow your logic.

pctek
12-09-2006, 08:38 PM
Can you imagine the size of rocket needed to lift a large solid object able to produce this noise?

Sonic booms are caused by objects exceeding the speed of sound. Weight hasn't got a lot to do with it.

mister harbies
12-09-2006, 08:52 PM
Were the police testing their new tasers in CHCH by any chance?

TideMan
12-09-2006, 09:00 PM
I was walking down the street.
At first I thought something large had been dropped from a crane, then I realised the whole sky above me was reverberating. Like thunder, but it was a cloudless day. And it went on for several seconds.
Nature's power is awesome, eh?

Jen
12-09-2006, 09:11 PM
Meteorite fragments could fetch a tidy sum if located. Wonder how many are out there right now looking for the impact area :p

Or maybe it wasn't meteor after all according to this NZ Herald readers (http://www.nzherald.co.nz/section/story.cfm?c_id=1&ObjectID=10400940) comment:
A dome object like it was silver grey in colour . It appeared instantly a large boom then it simply disappeared. :waughh:

gibler
12-09-2006, 10:23 PM
I bet the boy racers were thinking "What kind of bass sytem does it require to make that sound?"

Thomas01
12-09-2006, 10:35 PM
I'm sorry.

I can't follow your logic.

If space junk - man made, falls through the atmosphere it will be hollow light weight stuff - it will collapse quickly (if I remember rightly we tried to design equipment to withstand 12g max) So there will be little noise. Imagine having a heavy lorry crash and being able to hear it 60 miles away - not possible of course.
To produce the noise heard today requires something very big - very dense - very solid - very heavy. To have such an man made item in space would require a rocket beyond our imagination. Certainly my guess is at least several thousand times more powerful than anything we have so far. I could be wrong.
Tom

Graham L
13-09-2006, 06:00 PM
Some satellites weigh several tons, Thomas. When the ISS comes down, I hope someone will be able to make quite sure it lands in an ocean. Remember the fuss when heavy bits from a Soviet space object (including a nuclear reactor) landed in Australia?.

There are still some very powerful rockets capable of launching heavy objects.

The amount of noise objects produce as they enter would depend on the speed. Meteors are travelling very fast when they hit our atmosphere, expecially ones which have come from outside our galaxy.

Thomas01
14-09-2006, 10:50 AM
Some satellites weigh several tons, Thomas.

Agreed - But they are huge devices. More or less empty spaces - the bigger they are the less the inherent strength. A ping pong ball really as compared to a billiard ball. There are some relatively solid items in space stations etc, but consider the large size & weight of the space shuttle which broke up when it lost control - not much remained of it.
I thought that the meteorite must be at least the size of the meteorite in the Canterbury Museum (if you haven't seen it then make a trip to Christchurch and view it). And if I admit it - I also assumed that it was in fact considerably above this size - more the size of a lorry or bus.
It looks as though I was wrong!
There I've admitted it - I was wrong!
Tom

Thomas01
14-09-2006, 11:10 AM
Sonic booms are caused by objects exceeding the speed of sound. Weight hasn't got a lot to do with it.

Weight has everything to do with it. Today in NZ lots of guns will be fired which have a muzzle velocity above the speed of sound. Nobody more than a fairly short distance away will notice.
In 1968 I was fortunate (or unfortunate!!) enough to be part of the design team employed on the American supersonic passenger plane. Those of us who had worked on the Concorde remembered the problems with that aircraft - but they were nothing compared to the problems Boeings were running into. The aircraft was much bigger and considerably heavier than the Concorde and the extra sonic boom was a huge worry - in order to improve the lift/drag ratio we were also trying to get the beast to ride on its own shock wave. Wow - the mind boggles!
It was probably a good thing that the money ran out and the beast was cancelled.
Tom

personthingy
14-09-2006, 11:49 AM
I also assumed that it was in fact considerably above this size - more the size of a lorry or bus.
It looks as though I was wrong!
There I've admitted it - I was wrong!
TomI'm glad you were wrong!
I didn't hear it. I've worked out that at the time it hit i was on central Christchurch building site and the mild bang disappeared into the normal noise i was ignoring in my then environment. Had it have been truck size, i assume there would have been a nice crater to show it's location, and the bang would have stood out even on a building site.

For reference, both Graham and myself are Christchurch residents. And yes the rock in the museum is extremely cool :D