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03/11/2019 – Ephemeris – The Moon: Dark side, far side, which is it?

March 11, 2019 Comments off

Ephemeris for Monday, March 11th. Today the Sun will be up for 11 hours and 40 minutes, setting at 7:43, and it will rise tomorrow at 8:01. The Moon, 3 days before first quarter, will set at 12:54 tomorrow morning.

Tonight the Moon is at its crescent phase, meaning it is slightly closer to the Sun than the Earth is. Most of the Moon we see is in night. Some earth shine may be seen on its night side due to the big nearly full Earth shining on it. I get ticked sometimes when someone who knows better, especially in the media, mentions the dark side of the Moon when they should use the term far side, the part of the Moon that permanently faces away from the Earth. When the Chinese Chang’e 4 spacecraft landed on the far side of the Moon recently many headlines proclaimed that it landed on the dark side of the Moon. The Moon has a night side, as does the Earth, but that changes as the Moon rotates in the sunlight.  And the Moon does rotate.  It happens to be in sync with its revolution about the Earth.

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

Addendum

Crescent Moon

The crescent Moon tonight at 9 p.m. EDT, March 11, 2019. Created using Stellarium.

Moon ball

Demonstration of the Moon’s crescent phase with the Styrofoam moon ball we use for Project Astro held up to a light off frame to the right. The night side of the ball is illuminated a bit by the translucency of the ball, and the reflection off my hand. Note the roughness of the ball is visible only at the terminator.

The crescent Moon and its relation the Earth

The Earth and Moon if seen as a crescent, near side, far side, sunlit side and earth shine. Credit: me.