How and when to view Sunday's total lunar eclipse

On Sunday night if the skies are clear, Canadians will be able to watch one of the most beautiful celestial events there is: a total lunar eclipse.

This is the first total lunar eclipse of the year and the first since last May. The best part is it will be visible across the entire country, though not all Canadians will see the full five-and-a-half hour event.

The eclipse begins late Sunday evening and lasts until early Monday morning.

Lunar eclipses occur when the moon passes through Earth's shadow.

The moon actually has two shadows: One is the penumbra — Earth's fainter outer shadow — but it's almost imperceptible to the human eye. The most exciting and dramatic part, however, is when the moon glides across Earth's inner, darker shadow, the umbra.

During this time, depending on the atmosphere, the moon can appear to turn a shade of red, which is why sometimes total lunar eclipses are referred to as "blood moons."

This eclipse also occurs close to when the moon is at perigee, or closest in its monthly orbit — which is why this is sometimes called a "supermoon" lunar eclipse (though it's difficult for humans to notice the slight size difference).

And as if a "blood moon" and a "supermoon" weren't enough names for this event, this month is also the "flower moon." the name given by the Old Farmer's Almanac for this month's full moon.

Unlike total solar eclipses, where totality (when the moon covers the disk of the sun) can last just a minute or a few, totality in lunar eclipses can last for more than an hour.

In Sunday's eclipse, totality will last about 85 minutes.

The eclipse itself, however, will last roughly five and a half hours. It begins when the moon enters the penumbra, but as mentioned earlier, it will be imperceptible to the human eye.

The excitement begins when the moon enters the umbra. Initially, it will appear as though something has taken a little bite out of the moon. This is the partial phase of the eclipse. As the night progresses, however, that "bite" becomes larger and larger.

Then, as it enters totality, most of the moon may appear a faint reddish colour as Earth's atmosphere scatters the light from the sun, which will lie directly behind it. Light with longer wavelengths — such as orange and red — refract, or bend, around the Earth, where it eventually reaches the moon.

There are some predictions that, due to the dust released in the giant Tongan volcanoe eruption in January, the dust in the atmosphere may make this a dark eclipse: Instead of being red, it may be darkened by quite a bit.