[meteorite-list] Stunning shot of mercury

From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Wed, 8 Oct 2008 01:35:45 -0500
Message-ID: <00ed01c92910$18b4fde0$264de146_at_ATARIENGINE>

Hi,

The interesting thing about the bright rayed craters is this:
"...you'll see that almost all the bright small craters can be
seen to have rays, too. Over time, the solar wind and
meteorite impacts erase ray systems, so they come from
young craters, and young craters tend to have brighter
floors."

Doesn't this imply a substantial population of NMA's?
(That's Near Mercury Asteroids!) Or are they cometary
impacts? This raises a question. There have been many
searches for asteroids in intra-Mercurian orbits, quite
thorough ones. Such an "inner" asteroid zone has been
proposed by a number of astronomers, to account for
numerous mistaken observations of intra-Mercurian
"planets" and objects transiting the Sun. These searches
have ruled out the existence any intra-Mercurian objects
as large as or larger than 10 km, and it now widely believed
that there aren't any inner system asteroids.

So, what made these "recent" bright rayed craters on
Mercury? The age of bright rayed craters on the Moon
are thought to range from less than 800 million years to
yesterday. Since it is the solar wind that erases ray systems
and since the solar wind is much more intense at Mercury,
these craters must be younger than 800 million years.

Is this evidence of a high cometary flux? Is this evidence
of a now-depleted reservoir of inner system asteroids?
Is this evidence of a "recent" inner system bombardment
episode? (The surface of Venus is 480 million years old,
+/- 60 million years.)

It's what I like about the Universe. Always something new.


Sterling K. Webb
----------------------------------------------------------------------
----- Original Message -----
From: "Darren Garrison" <cynapse at charter.net>
To: <meteorite-list at meteoritecentral.com>
Sent: Wednesday, October 08, 2008 12:08 AM
Subject: [meteorite-list] Stunning shot of mercury


No, that isn't a particularly unwise order at a bar:

http://blogs.discovermagazine.com/badastronomy/2008/10/07/watermelon-planet/
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Received on Wed 08 Oct 2008 02:35:45 AM PDT