• Don SpainEmail author
Part of the Astronomer's Pocket Field Guide book series (ASTROPOC)


Posidonius (56 miles) is an older formation with rather low walls. There is a nice 6 mile crater off center on the floor and near a small central peak. There is a long ridge, beginning at the southeast and more or less paralleling the eastern rim, curving into the northern floor. In my 6 inch refractor there are several rills visible. The most prominent is the one near the western wall and ends at a ridge. There is a lot of detail on the floor of this old formation. Examine it 5 days after new Moon.

Chacornac (31 miles) is below Posidonius with walls less than a mile high. The floor is rough and there is a little 3 mile crater near the center.

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© Springer Science+Business Media, LLC 2009

Authors and Affiliations

  1. 1.Louisville Astronomical SocietyLouisvilleUSA

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