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

[Richard A. Kowalski]

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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