Home > Ephemeris Program, Phases, The Moon > 05/02/2017 – Ephemeris – Puzzling out the Moon’s history

05/02/2017 – Ephemeris – Puzzling out the Moon’s history

May 2, 2017

Ephemeris for Tuesday, May 2nd.  The Sun rises at 6:30.  It’ll be up for 14 hours and 17 minutes, setting at 8:48.  The Moon, at first quarter today, will set at 3:06 tomorrow morning.

The Moon will be at exactly first quarter at 10:47 p.m., so it should be split exactly in half by the sunrise line or terminator.  On the illuminated face of the Moon can be seen the dark gray spots called seas.  In dating the moon rocks brought back by the Apollo astronauts the dates tell the amount of time since the rocks were molten due to collisions.  The dates turn out to give clues to when the seas were formed, because they are actually large impact craters, which were filled in by the lava from the moon’s interior.  The oldest rocks on the Moon are 4.5 billion years old, dating from the formation of the Moon.  There’s another group about 3.9 billion years old dating to when many of the seas were formed in a cataclysm called the late heavy bombardment.

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


First quarter Moon

First quarter Moon with key to the lunar seas. Created using Stellarium.

Sym Latin Name           English Name       Age
 A  Mare Serenitatis     Sea of Serenity    3.85 to 3.92 billion years
 B  Mare Tranquillitatis Sea of Tranquility 3.92 to 4.55 billion years
 C  Mare Nectaris        Sea of Nectar      3.85 to 3.92 billion years
 D  Mare Fecunditatis    Sea of Fertility   3.92 to 4.55 billion years
 E  Mare Crisium         Sea of Crises      3.85 to 3.92 billion years
 F  Mare Frigoris        Sea of Cold        3.85 to 4.55 billion years

Data are from Virtual Moon Atlas




  1. svedlifestyle
    May 5, 2017 at 11:08 am

    Wow, thanks!

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