A red moon in the night sky

                              If the night sky is clear very early on Tuesday morning, we will be able to watch a total lunar eclipse, as the full moon moves into the Earth's shadow.
                              The first easily visible change in the moon's appearance will occur at 1:58 a.m., marking the start of the partial eclipse phase of the moon.  About an hour earlier, the moon will begin to dim very slightly as it enters the outer and far less dark region of the Earth's shadow known as the penumbra.  The penumbral eclipse phase is not very noticeable because the Earth does not block out all of the direct sunlight reaching the moon.
                             At the beginning of the partial eclipse, the full moon just begins to entire the darker part of the Earth's shadow known as the umbra.  Imagine the moon as a "cookie" in the sky with a bite being taken out of its left side as a it slowly advances into the dark umbra.  The bite grows bigger and bigger until the moon is totally within the umbra, and that marks the beginning of the total eclipse at 3:06 a.m.
                             As a result of a tilt in the moon's orbit, every month the full moon usually passes slightly above or below the Earth's shadow, so we don't see an eclipse every month.  This month, the full moon, the Earth and the sun line up to give us a total lunar eclipse.
                             During totality, from the moon's point of view, the sun is completely blocked by the Earth, preventing any direct light from the sun reaching the moon.  But why during totality doesn't the moon appear black and disappear?  Because scattered sunlight, which we see as a red sky before sunrise and after sunset, can trickle through our atmosphere around the edge of the Earth and dimly light the moon with interesting copper-to-reddish colors.
                             The Chinese lunar exploration spacecraft Chang'e 3 is now on the moon.  If it can look toward the Earth during totality, it will see a dark circular Earth completely hiding the sun, with the Earth enclosed in a bright shining ring of red light from all of our planet's red skies at sunset and sunrise.
                             While eclipsed, the moon's dark shading varies considerably from eclipse to eclipse because its passage through the umbra is sometimes a bull's-eye and at other times, such as in this month, it passes through the outer portion of the umbra.  Our atmosphere's ozone content can offer a glimpse of a blue color at the edge of a totally eclipsed moon.
                              The middle of the eclipse will occur at 3:45 am.  The total eclipse ends at 4:24a.m., followed by the moon growing back to its normal appearance during the partial phase of the eclipse.  That ends at 5:33 a.m., making the "cookie" whole again.  About an hour later, the moon leaves the penumbra part of the Earth's shadow.
                              If you miss this total lunar eclipse, the next one, which will also be visible from our area, occurs in the later morning hours of Oct.8.  Another one occurs even later in the morning of April 4, 2015.  But the full totality duration of these eclipses cannot be seen from our area because the moon sets before totality ends.