A Long, Cold Mare
Explanation:
Maria seem to come in all shapes and
sizes - from the large, near circular Mare Imbrium to the small Mare Anguis (which
I always think of as anguishing over its impudence in being a mare rather than a
lacus). But the strangest mare of all is Frigoris, which stretches about 1600 km
from east to west, but only 200 or so km from north to south. Frigoris clearly does
not fill a circular impact basin, and the best that can be said is that its mare
lavas occupy a concentric depression around Imbrium, just as do Mare Vaporum and
Sinus Aestuum. The Frigoris lavas seem to be of somewhat diverse ages and compositions.
KC's image illustrates that large parts of the mare are lighter than other parts,
partially because it is crossed by some bright rays.
But part of the light hue is due to a difference in composition - the Galileo multi-spectral
image shows that most of Frigoris is gold-hued, but
the western part is blue. And gold = titanium-poor, and blue = intermediate titanium
lavas. Crater counts indicate that most Imbrium lavas are Imbrium in age, but the
darker patches north of Plato and the broad region around Harpalus are Eratosthenian.
—
Chuck
Wood
Technical Details:
September 26, 2004, a mosaic of 4 images using a 10" Newtonian and a webcam. CAW
has enhanced the image using the Photoshop unsharp mask filter.
Related Links:
Ages
of Mare Basalts...
Rukl Atlas of the Moon, Sheets 2, 3 & 4
