06/23/2015 – Ephemeris – What can you tell about the appearance of the Moon to the naked eye?

Ephemeris for Tuesday, June 23rd.  Today the Sun will be up for 15 hours and 34 minutes, setting at 9:32.   The Moon, 1 day before first quarter, will set at 1:31 tomorrow morning and tomorrow the Sun will rise at 5:57.

The Moon is at nearly half phase or first quarter.  The unaided eye can see that the Moon has darker and lighter areas.  The Greeks, who thought the objects in the heavens were perfect thought that the Moon was a silvery sphere.  They never quite figured out why the moon had this mottled appearance.  So why are the bright parts different from the darker parts?  The bright parts are called the highlands and are the oldest part of the Moon’s surface.  It’s saturated with craters from impacts since the Moon formed.  The dark areas are roughly circular, and are really vast craters that penetrated through the Moon’s crust to bring up molten lava that repaved the surface of the Moon some 500 million years after it formed.

Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

The Moon tonight (June 23, 2015). Look at the difference in the surface albedo (reflectance) between the light and dark areas and wonder about their origins. Created using Virtual Moon Atlas.