Bob Moler's Ephemeris Blog

Ephemeris for President’s Day, Monday, February 17th.  The sun will rise at 7:39.  It’ll be up for 10 hours and 34 minutes, setting at 6:13.   The Moon, 3 days past full, will rise at 9:17 this evening.

The bright Moon is now a waning gibbous phase,  The right edge of the Moon is now in night as the sunset terminator slowly advances across the moon.  Tonight the Sea of Fertility is half in daylight on the right side of the Moon.  A telescope looking at it can spot the double crater of Messier and Messier A, a funny impact where the small asteroid skipped producing two craters and a double ray of ejecta.  On the other side of the moon the largest sea Oceanus Procellarum, or Ocean of Storms can be seen in its entirety to the left limb of the moon.  It happens that the moon is rotated toward us on that side, an effect called libration.  The effect is due to the moon’s uneven velocity around the earth.

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

Addendum

The moon at 9 p.m. on February 17, 2014 showing Oceanus Procellarum and the craters Messier A and B. Created using Virtual Moon Atlas.

Closeup of the craters Messier A and B showing their twin rays. Created using Virtual Moon Atlas and the Lunar Reconnaissance Orbiter images. Credit: NASA.

Extreme closeup of the craters Messier A and B showing their twin rays. Created using Virtual Moon Atlas and the Lunar Reconnaissance Orbiter images. Credit: NASA.