"Half Moon"
22.2 day old Moon
49% of Full
updated: Mar 22, 2014, 11:00 AM
By Chuck McPartlin
As the Moon (click here) orbits the Earth, and the Earth and Moon travel together around the Sun,
we get to see orbital mechanics in action. Every month (think moonth), we are treated
to a beautiful sequence of phases as the illumination of the Moon's surface changes.
Because we're dealing with multiple celestial bodies with multiple motions like
rotation and revolution, it may not be obvious what's really going on. This leads to
misconceptions like a permanently "Dark Side of the Moon", the Moon is "only visible
at night", or that the lunar phases are caused by the shadow of the Earth. Let's take
a look at why we see the Moon the way we do in our Santa Barbara sky.
Let's watch the phases of the Moon as seen from Earth, starting with what has
traditionally been called a young or New Moon - the tiny sliver you see in the west
near the setting Sun. As the sky darkens, you may see that the rest of the Moon's face
is faintly illuminated, often called "the New Moon in the Old Moon's arms". This is
Earthshine, light reflected from the bright clouds, snows, and oceans of the Earth.
