Return to the Cloudy Nights Telescope Reviews home pageAstronomics discounts for Cloudy Nights members
· Get a Cloudy Nights T-Shirt · Submit a Review / Article

Click here if you are having trouble logging into the forums

Privacy Policy | Please read our Terms of Service | Signup and Troubleshooting FAQ | Problems? PM a Red or a Green Gu… uh, User


Poster: cildarith (see all of this user's photos)
Description: Fracastorius
Partially Submerged Walled Plain
Parks Astrolight EQ6 • 6" f/6 Newtonian Reflector
7.5mm Parks Gold Series Plössl + 2x Barlow • 240x
Field of View Not to Scale
13 January 2008 • 01:15-02:05 UT

On the southern shore of Mare Nectaris, its floor flooded and its walls half-submerged by the basaltic flows generated by the massive impact which created the Mare, you will find the horseshoe-shaped lunar crater Fracastorius. With a diameter of 124 km, Fracastorius is one of the finest examples of a partially ruined walled plain on the Moon. A few low hills at the northern mouth of the bay are all that remain of the crater's northern wall. The south wall is heavily eroded; the east and west walls have held up much better over the eons.

The large crater preceding (celestial west, lunar east) the walled plain is designated Fracastorius B (27 km). Continuing clockwise around the rim of Fracastorius brings us to a smaller crater, Fracastorius A (18 km). Fracastorius C (16 km) is next; it has a peculiar depression extending toward the north, parallel to the walls of the main crater. Fracastorius D (28 km) is a complex structure composed of multiple impacts and breaks the following wall of Fracastorius. Finally, Fracastorius H (21 km) is a large, D-shaped depression that seems to have been partially destroyed by the Fracastorius impact.

While the floor of Fracastorius contains a lot of detail, must of these features are quite minute and have thus far eluded by efforts to detect them in my telescope. The albedo features of the floor that I can see, however, are interesting and may be the result of some of these features lying just beyond my ability to resolve them. There is a persistent impression of an uplift toward the center of the crater – perhaps a submerged central peak.

Fracastoriius is named in honor of Girolamo Fracastoro (1483-1553), an Italian physician, astronomer and poet.

Post Laureate

Registered: 3/7/2005
Posts: 4957
Wonderful sketch and detailed report Eric!

I've discovered the same thing about the floor of Fracastorius, it must require a combination of excellent seeing and the right magnification to resolve these finer features.

Mon Jul 13, 2009 12:59pm
Click here to see this users profileVisit this user's gallery 

Powered by: PhotoPost PHP 3.3.1
Copyright 2002 All Enthusiast, Inc.