(meteorobs) On the connection between nearby NEAs and the recent increase in fireballs...

[chergen]

Mike and others,

Thanks for your comments and vibrant discussion.

> To summarize in laymans terms without putting words in your mouth, I
> think what you are saying is:
> 
> There is no correlation to witnessed fireball activity on Earth and
> NEOs that are reported in close approach to Earth, because, these
> reported NEOs are only a small subset of the actual NEOs flying by
> everyday anyway.
> 
> My understanding of what Chris is saying is -- sometimes fireball
> rates are going to go up and sometimes they are going to go down and
> that is just the way it is. Rates will ebb and flow, and 
> correlating a perceived increase in fireball rates for a certain 
> time with approaching NEOs in that same time frame is a fallacy. 

Mike, your layman summary is pretty much spot on. 

But to clarify, even though we can't use the number of close 
approaching NEAs as a predictor of fireball activity, that 
doesn't mean the rate of fireballs is constant throughout the
year. We know that the number of major meteor showers is higher
during the 2nd half of the year and the same is true for the
Sporadic meteor population (Weigert et al. [2009] finds that
the Sporadics originated from the major showers; hence, the
correlation between lots of major showers and the high rate of 
Sporadics). Though the major showers and Sporadics are mainly
cometary in origin and many fireballs are asteroidal, it still 
wouldn't be a surprise to find some seasonal variations in the 
flux of fireballs, as well as very small NEAs. 

As mentioned in other posts we have all heard of times when
fireballs are supposed to be more prevalent such as in the Fall 
(probably due to the Taurids), in January/February, April and 
June. Then again that's more than half the year so perhaps
fireballs are always "prevalent". 

It would be interesting to know if any of the long-running 
fireball networks have detected any seasonal variation in rates 
(outside of the major showers)?

- Carl