September 7, 2014
image by K.C. Pau, Hong Kong
Although the lunar crater Menelaus is named for a Greek astronomer in ancient Alexandria, I prefer to think instead of another Menelaus, the warrior husband of Helen of Troy. The lunar Menelaus is a 27 km wide, 2.6 km deep crater straddling the rim of the Serenitatis basin and the mare that fills the basin. If the mare really were an ocean of water, Menelaus would be the castle guarding this stretch of the coast. But the real interest here is the cluster of rilles just north of Menelaus. These Menelaus Rilles are in the older and darker annulus of Serenitatis lavas. There seem to be two families of rilles - first are the three to four strands of rilles that parallel the basin rim. These probably formed by cracking as the mare-heavy center of Serenitatis subsided. Nearly at right angle to these narrow rilles are two or three shorter rilles that are partially lines of collapse pits - see Lunar Orbiter image for details. KC's low sun image reveals that the western most of the rilles cuts thru the middle of a low dome. The ALPO dome map shows six possible domes in this region, but KC's great image renders that number questionable.
This is a classic LPOD from 10 years ago today, September 7, 2004.
10" f/6 Newtonian with 5X barlow and mosaic of two images
Rükl Atlas of the Moon Sheet 23
Yesterday's LPOD: Rille Tour
Tomorrow's LPOD: Classic Views