The velocity of meteors depends on whether they are seen before or after
midnight. Before midnight what we see are objects the earth runs into
at its own orbital velocity of approx. 67,000 mph +/- the velocity of
the object relative to earth. After midnight what we see are objects
that are moving fast enough to catch up with the earth or else make a
direct side impact.
Chuck Norcutt
On 3/5/2012 11:12 PM, Jim Nichols wrote:
> Chuck, anything moving through the air supersonically (>620 mph) will form a
> shock wave. Normally, at Mach 2, such as the Lockheed flights out of
> Marietta, GA that pass over us each week, you only hear the noise when the
> conical bow wave passes your location. I have cracked drywall in the
> kitchen ceiling to attest to that.
>
> At high supersonic speeds such as you are suggesting, the shock sweeps back
> very steeply, so, unless it was aimed precisely at you, you would likely not
> be aware of it at all. If it passed over your location in a more horizontal
> path, the sound would be more likely be noticed.
>
> Jim Nichols
> Tullahoma, TN USA
> ----- Original Message -----
> From: "Chuck Norcutt"<chucknorcutt@xxxxxxxxxxxxxxxx>
> To: "Olympus Camera Discussion"<olympus@xxxxxxxxxxxxxxxxx>
> Sent: Monday, March 05, 2012 10:01 PM
> Subject: Re: [OM] Sky falling in on Kodachrome
>
>
>> I don't know why it should be impossible to produce a sound. The reason
>> we have fire in the fireball is that you've got a bid stone tearing
>> through the atmosphere at perhaps 30,000 mph. It's trying to push a
>> hell of a lot of air out of the way in a very short time. Moving air
>> makes noise.
>>
>> Chuck Norcutt
>>
>>
>> On 3/5/2012 10:40 AM, Ken Norton wrote:
>>>> Comet fragments and meteors in the dead of the night far away from
>>>> urban noise can be amazing. If the upper atmophere is calm you can hear
>>>> a
>>>> faint "whoosh". I've heard it twice now, always out in the middle of
>>>> bloody
>>>> nowhere.
>>>
>>>
>>> I was reading something about that a couple years ago. I too have
>>> heard meteors as they turn into little fireballs. The laws of physics
>>> say that it's impossible.
>>>
>>> But according to this research, it has something to do with the
>>> generation of radio frequencies as it passes through the ionosphere or
>>> something like that. The RF signal is either exciting our brain tissue
>>> or is making loose dirt move. I don't remember the details as I must
>>> have read this article late at night in an attempt to bore myself to
>>> sleep.
>>>
>>> Whatever causes it, it is neat.
>>>
>>> AG
>> --
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>
>
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