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(meteorobs) meteor? meteoroid? how many?




This was inadvertently sent to owner-meteorobs, so I'm reforwarding it for
Sigrid. BTW, Sigrid, my own amateur take is that you actually have the wording
dead-on! "Meteors" DOES refer to the electromagnetic emission from an entering
meteoroid: so saying "detectable meteors" would be redundant. Further, below a
certain kinetic energy (and so below a certain minimum mass for interplanetary
particles), I believe meteoroids actually fail to produce detectable emissions,
no matter HOW sensitive the detector! So, assuming there is a radar sensitive
enough to detect meteors right at this lowest threshold, "1 billion meteors" is
an entirely correct way to say it! Again, according to my amateur take... :)

Clear skies!
Lew Gramer


------- Forwarded Message

Date: Fri, 29 Oct 1999 09:31:57 +1200
To: owner-meteorobs@venus.jovian.com
From: Sigrid Close <sigrid@ll.mitdot edu>
Subject: meteor?  meteoroid?  how many?


I thought I'd go right to the source.  I'm getting published in the MIT
Lincoln Lab journal and I start out by saying

"Approximately one billion meteors enter the Earth's atmosphere daily".


Does anyone have issue what that statement?  This was calculated from
a detection rate of 1 meteor head echo per second in our radar's 3 degree
beam (spanning 70 to 140 km altitude).

Also, since I'm talking about head echoes, should I always use the
word meteoroid and never use the word meteor?  (I had thought a 'meteor'
only referred to that streak of light detected optically).

Thanks!
Sigrid

-------------------------
MIT Lincoln Laboratory
Work Phone: 805-355-6588
Home Phone: 805-355-4544</italic>
------- End of Forwarded Message


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