Archive for April 7, 2014

04/07/2014 – Ephemeris – Why does the Moon have all those craters?

April 7, 2014 Comments off

Ephemeris for Monday, April 7th.  The sun will rise at 7:12.  It’ll be up for 13 hours and 4 minutes, setting at 8:17.   The Moon, at first quarter today, will set at 3:37 tomorrow morning.

Today the Moon is at first quarter.  That moment in time actually occurred a couple of hours ago, so by tonight the Moon’s terminator, the sunrise line on the Moon will be slightly bowed to be a slight gibbous phase.  With binoculars or small telescope it’s a fine time to spot craters and mountains near that terminator where the shadows are longest.  On the Earth mountains are thrown up by the collision of tectonic plates or volcanoes.   There are no tectonic plates as such on the Moon.  Mountains that we recognize are the walls of the seas, which are really vast craters caused for the most part by collisions with small asteroids.  The reason the Earth doesn’t carry those scars is that the Earth erodes and recycles its surface.

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


The Moon

The Moon tonight (10 p.m. April 7, 2014). Created using Virtual Moon Atlas.