[Prev][Next][Index][Thread]

Re: (meteorobs) 2 Questions (Fireballs)



Dustin,
          I can't supply you with exact answers, but I can say this:  The
persistent train would not be visible (at night) at 80-100 Km high were it
composed of water vapor.  Instead, it is a mass of glowing, ionized air
particles.  Given that it lasted so long, and you actually squinted when the
fireball appeared, I would *venture* a feeble guess that it was brighter
than the full moon.  Maybe -13 -17?  Estimating magnitudes of such
brightness is very, very difficult, even for very experienced observers.
For instance, I still don't honestly have any idea of an estimation of a
ceratin '98 leonid fireball I saw, only that it was bright enough to give my
observing partner a brief case of the willies.
        Noticeable shadows begin to be cast at around -6/-7, I believe, but
I will await the reply of a more experienced observer on this, also.
Kim Youmans


Dustin wrote:

> I have two questions about a fireball observation I made during the 99
> Leonids.
>
> 1.   At what magnitude will a fireball cast noticeable shadows on a dark
> night ?
>       (It was so bright it made me squint and I noticed the shadows cast
> around me)
>
> 2.   Why would the "train" last for almost 50 minutes, (most trains I
> read about are only 2 or 3 minutes at best)..... could the particles in
> the train supply a condensation point source for atmospheric water
> vapour to condense yielding a cloud.   (I was in a clearing between two
> storm systems, so the humidity in the upper atmosphere could have been
> fairly high)   Any thoughts ?
>
> Thanks,
> Dustin Brown
>
> To UNSUBSCRIBE from the 'meteorobs' email list, use the Web form at:
> http://www.tiacdot net/users/lewkaren/meteorobs/subscribe.html

To UNSUBSCRIBE from the 'meteorobs' email list, use the Web form at:
http://www.tiacdot net/users/lewkaren/meteorobs/subscribe.html

References: