Proclus Home

Proclus is a small crater (only 29 Km in diameter) but very interesting nevertheless.  It is very young, certainly less than 1,000 million years and probably even younger.  We can see this from the fact that its ejecta are still very light in colour.  Over the eons, the lunar surface darkens by "weathering" - the continual bombardment by micro-meteors from space. The underlying rock is much lighter.  Thus when a large meteor strikes the surface and creates a crater, it throws out the lighter-coloured underlying rock and spreads it all around over the darker pre-existing surface.  Then slowly over time this darkens.  The ejecta are not so obvious in this picture but can be seen more clearly in my picture of the eastern maria in which Proclus is the tiny white circle just west of Mare Crisium.  The ejecta tell us something else as well.  It can be seen (again more clearly in the other picture) that the ejecta are not evenly distributed around the crater.  This pattern tells us that the projectile hit the Moon at a very shallow angle (probably no more than 15°) and came from the south-west.  Such impacts throw most of the ejecta forward, but also produce strong rays boadering a shadow zone up-range.

Move your mouse over the picture to see the names of the various craters.

The other interesting featue of this picture is Palus Somni.  This looks like a dark patch of terrain that has been given the name The Marsh of Sleep but in fact it is the same hue as most highland terrain (compare with Macrobius and the region to the east).  It is simply an area outlined by the two bright, fresh rays from Proclus, and missed by the ejecta from this very-oblique impact.
The scale markers are approximately 100 Km north and east.
The picture was taken with a ToUcam attached to my LX200 on 2nd June 2006 at 21:18 UT, when the Moon was 6.4 days old.

Date and Time: 2nd June 2006 21:18 UT
Camera: ToUcam 740K
Telescope: LX200 at prime focus with IR-pass filter
Capture: K3CCDTools. Low gamma, 1/33", 2% gain, 604 frames
Processing: Registax. 142 frames stacked.  Wavelets 1 = 10, 2 = 5, histogram 0-150
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