[meteorite-list] Earth close-approach

From: Matson, Robert <ROBERT.D.MATSON_at_meteoritecentral.com>
Date: Thu Apr 22 10:01:34 2004
Message-ID: <AF564D2B9D91D411B9FE00508BF1C86901B4E1E6_at_US-Torrance.mail.saic.com>

Hi Pierre and list,

> I am a bit surprised by all this fuss in the media every few months
> about how lucky we are escaping once again the big hit. As a
> scientist I can say that the probability that an asteroid cruising
> nearer to earth than the Moon actually hit the earth is 1/10000*...

> *: if you want a more precise figure: square of the ratio of earth
> radius to moon-earth distance.

The actual value is more like 1 in 3644. Closest approach for this
asteroid was less than 1/3 the moon's distance (~120,000 km). A
random object that pierces the 120,000-km-radius sphere around
the earth has a 1 in 354 chance of hitting it.

Mind you, for every asteroid like this one that passes within the
moon's distance of the earth, many times that number go undetected.
Food for thought... --R

P.S. Another way of envisioning the closeness of this flyby is
to consider that if the asteroid's orbit intersected the earth's
orbit, it only missed us by about 67 minutes.
Received on Fri 21 Jun 2002 03:28:36 PM PDT