October 24, 2004

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A Long, Cold Mare



Image Credit: KC Pau

A Long, Cold Mare

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

Yesterday's LPOD: Imaging the First Lunar Photographer

Tomorrow's LPOD: Modeling Domes

Author & Editor:
Charles A. Wood



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