[meteorite-list] Many Newly Discovered NEOs with Close approach 6APR-15APR2011

From: Richard A. Kowalski <kowalski_at_meteoritecentral.com>
Date: Wed, 06 Apr 2011 15:26:06 -0700
Message-ID: <4D9CE87E.9050108_at_lpl.arizona.edu>

Hey Dirk,
since there is a small amount of discussion about sensationalism in the media in
relation to meteorites, I hope you don't mind too much about your latest post.

First thanks for your kind words about CSS.
I direct people to your website and look at the two columns listed as "Miss
Distance". One is AU for Astronomical Unit, and the other LD for Lunar Distance.
The distances in human measurements are in the legend.

The important thing to note here are objects that pass closer than 1 LD. Note
that this is a sphere around the earth, not just along the moon's orbital plane.
On your chart there are only 2 that fit this bill. It is highly unlikely that
there will be any noticeable effect in the number of fireballs due to these
close approaches. The ones more distant than the moon most assuredly will have
zero effect.

It may be surprising to learn that we at CSS discover a number of small close
approachers every lunation. It happens so often now that it no longer makes the
news. It may be even more surprising to learn that it is estimated that about
1000 natural objects pass by the earth closer than the moon each and every
month! There are many reasons why we don't discover this many each month, but it
isn't due to a lack of trying. More than half the sky is unobserveable because
of the Sun. Another half of the sky is unobserveable from any one site because
the earth is in the way. Another big reason for the limited number of
discoveries is because these objects are so faint that they can't even be
detected except for the last few days before the encounter. If we happen to
point the telescope at the part of the sky one occupies the day before it
becomes bright enough to observe, or even just an hour before, we just can't
detect it.

Luckily these small rocks will do little more than make the wonderful light
shows and sometimes even drop meteorites to the surface.

The point of my post is to suggest that is impossible to say if any one fireball
was due to it being a companion of a known close approacher or if it just
happens to be one of the other approximately 1000 objects that occupy the region
around the earth closer than the moon each and every month. As a concrete
example I'll cite a rock I picked up right at the beginning of February, 2011
CQ1. This rock passed only 5480km (3400 miles above the surface of the Pacific
Ocean making it the closest approach of any known asteroid ever. I'm unaware of
any increase in meteors spotted around the time of closest approach much less
any fireballs.

Yes, CQ1 is much smaller than the ones you cite, but it also came much, much
closer too.

Hope this helps.

-- 
Richard Kowalski
Catalina Sky Survey
Lunar and Planetary Laboratory
University of Arizona
http://www.lpl.arizona.edu/css/
--- On Wed, 4/6/11, drtanuki <drtanuki at yahoo.com> wrote:
 > From: drtanuki <drtanuki at yahoo.com>
 > Subject: [meteorite-list] Many Newly Discovered NEOs with Close approach 
6APR-15APR2011
 > To: meteorite-list at meteoritecentral.com, "Global Meteor Observing Forum" 
<meteorobs at meteorobs.org>
 > Date: Wednesday, April 6, 2011, 2:39 PM
 > Dear List,
 >
 > Hope that everyone will get to see some meteors from debris
 > leading or following these NEOs close approaches.
 > Catalina and others have just found several new ones.
 >
 > 
http://lunarmeteoritehunters.blogspot.com/2011/04/elevated-detected-neos-close-approach.html
 >
 > Dirk Ross...Tokyo
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Received on Wed 06 Apr 2011 06:26:06 PM PDT