Mare Smythii

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

Mare Smythii fills an ancient impact basin centred at 87° E and so only visible with favourable librations.  Here the libration is 4° 26' in longitude (and zero in latitude), which is about half the maximum possible.  The basin is approximately circular and dates from the early days of the Moon (more than 4,000 million years ago).  It has been flooded with lava at least twice, the older lava being heavily cratered and indistinct, but the northern part of the mare is darker and much less heavily cratered so must be much younger (less than 2,000 million years).  This diversity is visible in my image as the impact basin extends from the dark patch surrounding Peek right down to the crater Kiess, and the general outline of the western rim can be seen.  The eastern rim is probably over the limb;  it is tempting to interpret the bright edge as the eastern rim (and the irregular form supports that interpretation), but the brightness may in fact be an artifact of the image processing. The scale markers are approximately 100 Km north and west.  As always in areas near the limb, these markers are deceptive, but they apply south and west of Nobili. A mosaic of this picture with one to the north can be seen here. This picture is a mosaic of two pictures taken with a ToUcam attached to my LX200 on 10th December 2005 at 17:20 UT when the Moon was 9.8 days old.

Date and Time	10th December 2005 17:20 UT
Camera	ToUcam 740K
Telescope	LX200 at prime focus with IR-pass filter
Capture	K3CCDTools. Low gamma, 1/33", 10% gain, 312 & 368 frames
Processing	Registax. 79 & 108 frames stacked. Wavelets 1-2 = 10, histogram 30-255

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