Home > Ephemeris Program, The Moon > 04/11/2016 – Ephemeris – The margins of the Moon

04/11/2016 – Ephemeris – The margins of the Moon

April 11, 2016

Ephemeris for Monday, April 11th.  The Sun will rise at 7:04.  It’ll be up for 13 hours and 18 minutes, setting at 8:23.   The Moon, 2 days before first quarter, will set at 1:28 tomorrow morning.

Lets check out the Moon tonight.  The Moon’s terminator, now the sunrise line traversing the Moon is beginning to uncover the dark Mare Tranquillitatis or Sea if Tranquility on the equator of the Moon.  The small round prominent sea on the right side of the Moon is Mare Crisium, or Sea of Crises.  At the limb beyond Crisium is Mare Marginis or sea at the Margin, and below it also at the edge is Mare Smythii, or Smith’s Sea, named after William Henry Smith a 19th century British astronomer.  These last two seas are only visible when the Moon appears to rock to the left and reveals them.  This is called libration caused by the fact the Moon rotates at a constant rate and it orbits the Earth in an ellipse, changing it’s speed.

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

Addendum

Moon April11, 2016

Map of the Moon for April 11, 2016. The arrow shows the point of maximum libration for that date. Created using Virtual Moon Atlas.

Apollo 8 image annotated

Photo of the receding Moon taken by the Crew of Apollo 8 as they started to head home showing the near side on the left and the far side on the right. I’ve annotated the seas which I’ve described above. Credit NASA.

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