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Re: PHA needs a fourth decimal point


> 
> The 0.000 AU is a truncated value (yes the 4th decimal place is missing),
but
> they don't list the date for the close approach.  
> According to my calculations, the asteroid made a recent close flyby of
Earth on
> Jan 29 at a distance of 0.201 AU.  The current orbit is calculated on
only 
> 12 days of observations (ie: large error bars), so the orbit is still has
a lot of
> play in it until additional observations can nail it down.  Also, it
looks
> to me the 0.000+ AU encounter is sometime way into the future, at least
> not within the next 100 years since 1998 FW4 is not listed in the table
for 
> close approaches through the end of the 21st century.
> 
> Ron Baalke



Thanks Ron,
 This is pretty much Gareth's answer was too but I must admit your command
of
the facts of this particular asteroid is impressive. 

I will send you my response to Gareth in the hope that it applies to your
answer too.

I understand this answer.  MIN. very low values are potential impacters. 
In conjunction with a good orbit  and in conjunction with your actual PHA
close approach list, which I understand is now updated through the 2031 and
some actual close approaches till the 21th century, we can tell exactly if
this asteroid with a very low MIN value will come close.  1998 FW4 does not
show up on any actual close approach list which means we are safe from
impact with this asteroid through the year 2100 I quess. On the other hand
looking at the long term over 100's of thousands of years with a MIN. value
as 1998 FW4 asteroid has, the probability is that a very close approach
will occur and eventually even impact may occur.   

I see that your concerned about close approaches over the short term since
really this all that can be computed realistically.  The NEO survey is
important and must go on to completion but I am not worried about an impact
over the short term from PHA's.  I freely admit that an impact is possible
in the next 200 years of some kind probably of a smaller variety asteroid. 
I think it is most probably that the survey of all NEO will be completed
and all of the approximately 2000 PHA will be shown NOT to impact the earth
in the next 100 years or so.  We will  know which ones are most likely to
impact the Earth over the long term (million of years) and which most
likely will not. I once read that about 40% of all these NEO's will impact
the Earth sometime over the lifetime of the Earth. Maybe after all the
PHA's are known we can categorize then into different degrees of dangerous
asteroid.  Class A most dangerous and Class X least.

I feel the the real danger to Earth is not from PHA's in the short term,
although PHA's can not be ignored, but the real danger will turn out to be
comets and comet showers which I feel we are in right now and also from
very long period NEO's we know nothing about. 

Victor


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Victor Noto - Kissimmee, Florida USA
vnn2@phoenixat.com
http://www.phoenixat.com/~vnn2/BIGROCK.htm
Website theme quote:
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the Big Rock giveth and taketh away all life!!" 
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