(meteorobs) Definition of a meteor (was Re: Fifth grade sciencebook)

GeoZay at aol.com GeoZay at aol.com
Thu Apr 28 13:54:15 EDT 2005


 
>> What about the meteoroid that skipped out of  the
Earth's atmosphere in 1972?  Is it no longer a meteoroid, as it  spent some
time in our upper atmosphere as a fireball/meteor?  What  would you call it
now?<<

 
I'd still call it a meteoroid. This object never entered the dark phase  of 
flight. The discussion was about those objects that have and entered free  fall 
flight. Since it was incandescent all the while in the atmosphere and left  
the earths influence, it still has an orbit of its own. The earth doesn't own  
it....it was just saying "Hello". :O)
 

>>  The definition of what is a meteoroid or  asteroid is still a gray area.
Was 60 tonne Hoba an asteroid or a  meteorite. <<
 
At this size, the object always had a considerable amount of cosmic  velocity 
all the way to the ground. It probably never left the light phase.  It never 
was just a falling object. Since the 60 ton Hoba  meteorite is less than 10 
meters in size, I'd still call it a meteorite. In  the IAU glossary of 
definitions, they define a meteoroid to being larger than an  atom or molectule, but 
smaller than 10 meters. If larger, it's refered to as an  asteroid. From the 
pictures I've seen of it, it appears to be less than 10  meters.
 
 
>>  As far as we know, all recovered meteorites are  asteroid
fragments unlike Cometary meteors.  Should there be a separate  definition
for either type of phenomenon?<<
 
Yes...if there is something different about them that would permit a  
distinction. Meteorites are already catergorized by their types and sub types.  If a 
Cometary meteor had a look that was remarkably different from that of an  
asteroidal meteor....then yes, a nomenclature should be made to show the  
distinction. 
George Zay


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