|
|
In article <dv7cll$8a8$1@xxxxxxxxxxxxxx>,
spope33@xxxxxxxxxxxxxx (Steve Pope) writes:
> Solarviews.com, in a discussion of the Oort cloud and comets.
Thanks. At first glance it looks like a nice site. The reference I
found is at http://solarviews.com/eng/oort.htm , and as far as I can
tell the estimate of 300 to 500 Myr is a statistical average. As I
wrote earlier, at first glance it looks high to me, but I haven't
tried to work out the correct value. It wouldn't surprise me if
there have been a few such encounters over the age of the solar
system, but offhand I don't see how to determine exactly when they
might have occurred. Maybe detailed study of lunar craters would
tell something. (I'm thinking of radioisotope dating of rock samples
associated with a large number of craters -- clearly a major
undertaking.) Does anyone know whether there's a pattern in the
dates of lunar meteorites?
--
Steve Willner Phone 617-495-7123 swillner@xxxxxxxxxxxxxxx
Cambridge, MA 02138 USA
(Please email your reply if you want to be sure I see it; include a
valid Reply-To address to receive an acknowledgement. Commercial
email may be sent to your ISP.)
|
|