A tilted cup
By Frank McCabe (Moon, Fracastorius crater)
Walled Plain Crater Fracastorius
Lunation day five has walled plain crater Fracastorius (124 km.) basking in the
morning sunlight on the south edge of Mare Nectaris as it has each lunar orbit
for more than three and three quarter billion years. The shallow plate shaped
basin that Fracastorius rests upon subsided from accumulated lava mass and this
over time tilted the crater toward the center of the basin. Eventually the lava
building up in the basin was able to find a breach in the low tilted north wall of
the crater and continued to flow in hiding the central peak and most of the north
wall beyond the breach. Some of the floor of Fracastorius is covered by lavas that
are lighter in color than the dark lava covering most of the Sea of Nectar.
Northward out into Mare Nectaris is the much younger, small (12 km.) bright rimmed
crater Rosse standing alone in this part of the lava sea.
For this sketch I used: black Strathmore 400 Artagain paper, white and black Conte’
pastel pencils and a blending stump. Contrast was slightly adjusted after scanning.
Telescope: 10 inch f/ 5.7 Dobsonian and 6 mm eyepiece 241X
Date: 5-22-2007 1:09-2:15 UT
Temperature: 22° C ( 72° F)
High thin clouds, calm
Seeing: Antoniadi III
Colongitude 331.8 °
Lunation 5.24 days
Illumination 32 %