A Lunar Favorite

Gassendi Crater, a Lunar Favorite
  
  Protruding inside the northern rim of the sea of moisture is the large floor
fractured crater Gassendi. If you close your eyes and try to picture in your mind
a large lunar crater, the image may look something like Gassendi. The 114 km.
walled plain crater is shallow as a result of lava upwelling across the floor
especially toward the east where the highest concentrations of floor fractures are
crisscrossing.  The shallow south end is tipped facing the center of Mare Humorum.
The northern end of the crater floor is rubble strewn and hummocky. The eastern
floor sports ridges and small craters in addition to rilles which were clearly
visible in the good seeing of the evening. The southern floor has an irregular
ridge that is parallel to the low rim. The large central peaks (1.2km. high) and
several smaller ones were seen in good relief with sharp black shadows. The deep
crater Gassendi A on the north rim of the larger Gassendi contrasted nicely with
respect to depth.
 Shallower and smaller Gassendi B was just north-north-west of A. The rough
highlands around Rimae Mersenius were visible to the west of these three craters
and low hills in the Herigonius region could be seen to the east of Gassendi. Mare
Humorum is estimated to be 3.9 billion years old and Gassendi perhaps 100 million
years younger. If Apollo 17 planners had chosen Gassendi as the last lunar landing
site we would likely know the ages today.
  
  
  Sketching
  
  For this sketch I used: black Strathmore 400 Artagain paper, 9”x12”, white and
black Conte’ pastel pencils and a blending stump. Brightness was slightly
decreased after scanning.
  
  Telescope: 10 inch f/ 5.7 Dobsonian 6mm eyepiece 241x
  Date: 9-23-2007 2:05-3:15 UT
  Temperature: 17°C (62°F)
  Clear, calm
  Seeing:  Antoniadi II
  Co longitude: 47.5°
  Lunation:  11.6 days
  Illumination: 82.7 %
  
  Frank McCabe