(meteorobs) Earth-grazer definition question

Roberto Gorelli md6648 at mclink.it
Fri Nov 20 03:31:18 EST 2015

On Thu, 19 Nov 2015 23:34:28 +0000 (UTC)
  LEO STACHOWICZ <l.stachowicz at btinternet.com> wrote:
> I'm afraid I can't answer, but I do have a related question that has 
>been on my mind: For the purposes of observation, if we are talking 
>about sporadics (or if the shower is unknown), how many degrees of 
>sky does a meteor have to travel before it can be called an 
>earth-grazer? Also, in the case of a known shower member, how far 
>from the radiant does the meteor have to start to be called an 
> Clear skies,Leo
>    On Thursday, 19 November 2015, 23:21, Thomas Ashcraft 
><ashcraft at heliotown.com> wrote:
>   Definition of an earth-grazing fireball from wiki:
> https://en.wikipedia.org/wiki/Earth-grazing_fireball
> " An Earth-grazing fireball (or Earth-grazer)[2] is a fireball, a 
>very bright meteor that enters Earth’s atmosphere and leaves again."
> Does an earth-grazer have to leave earth's atmosphere to be called 
>an earth-grazer?  Can it skim and ablate or burn up entirely and 
>still be termed an earth-grazer?
> Thanks in advance.
> Thomas

Sorry for the bad English.

It's to remember that there isn't a scientific definition of a 
"earth-grazer" in the same way that there isn't a scientific 
definition of "bolid".

An earth-grazer should to be the meteors/bolids that cross the entire 
sky from an horizon to the other in the opposite side, but this it's 
only the apparent view from a single observer in a single locality.
In the all day observations we can to said, IHMO, that a meteor/bolid 
was an earth-grazer when crossed over 90° of the sky, in this way each 
observer can to said a number of that events in its observer live.

Only the bolid of 10 August 1972, and perharps some others (not more 
of 5-10 in the past century), that entered and exit from the Earth 
atmophere, was a real earth-grazer, then if only it can to be 
denominated "earth-grazer" probably we never shall see in our live a 
similar phaenomena (earth-grazer).

Then the question is: do we are speaking of a apparent or of a real 
Best greetings.
Roberto Gorelli

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