Sunday's Total Lunar Eclipse

Sunday's Total Lunar Eclipse 

Sunday night (May 15), weather permitting, we have the opportunity to see a total eclipse of the Moon… well, you can see the earlier phases of it if you live in eastern Canada; in the west we’ll see less of it, and it will be lower in the sky.

A total lunar eclipse occurs when the Moon passes through the shadow of the Earth.  Earth’s shadow has two parts, really – a long conical cone of darkness where no direct sunlight reaches the Moon, and a secondary cone where some sunlight can be seen, but not from the full Sun.  Respectively these shadow zones are called the umbra and the penumbra.  Even in the umbra, some sunlight is refracted through Earth’s atmosphere, so the umbra is not totally dark.

A full moon occurs when the Moon is directly opposite the Sun in relation to the Earth, and since that is where Earth’s shadow is, lunar eclipses only occur at the time of a full moon!

As the Moon enters the penumbra (the partial shadow), it begins to fade.  The total phase will begin as Earth totally blocks the direct sunlight reaching the Moon (the umbra), at which time we can see the dark shadow of Earth begin to creep across the face of the Moon.  

The times are for BC and Eastern Daylight.  For AB/Sask, add 1 hr; for MB, 2 hrs.; and the Maritimes, 4 hrs (4:30 in Nfld) to the BC time.  

Earth’s dark shadow will touch the Moon around 7:27 p.m. Pacific Time (10:27 p.m. EDT).  Unfortunately for us in BC, the Moon doesn’t rise until 8:50 p.m., however it will be higher in the sky the further east one is, meaning more of the eclipse will be visible,.

Totality – when Earth’s shadow totally covers the Moon – begins at 8:28 in BC, so totality starts just before we can even see the Moon.  Alberta and east will have the Moon above the horizon when totality starts (11:28 EDT), but even in Alberta the Moon will just be rising.  The Moon will take on an orangish or reddish hue which is the result of the sun’s rays passing through Earth’s atmosphere, with those colours being refracted more inward into the shadow.

The deepest shadow, and therefore the deepest colour, occurs at 9:28 PDT (12:28 a.m. EDT) meaning the deepest phase will be visible all across Canada.

The Moon begins to come out of Earth’s direct shadow just before 10 p.m. PDT (1 a.m. EDT), and the last vestiges of that shadow leave the Moon just before 11 p.m. PDT (2 a.m. EDT)., after which the Moon will slowly brighten again over the next hour or so.

Make sure you dress warmly if you are going to spend much time observing the beauty of this eclipse.

Clear skies.
David