Starwatch: The total lunar eclipse drought is over!

January 20, 2019

I want you to do anything you can do to make sure we have clear skies. This Sunday night.

Pray, mediate, hold a hair dryer to the sky, whatever ever you can do leave the skies clear enough to see the first great total lunar eclipse in Rochester since late September 2015. It’ll be the last one we see around here until 2022.

It’s an extra great lunar eclipse this time because you won’t lose too much of your beauty sleep. This will be a near-prime-time total lunar eclipse that will begin at 9:34 p.m. and will be completely over by 12:51 a.m. Monday, Jan. 21.

This should be quite a show, as the moon slips into a ruddy hue during totality. Lunar eclipses occur when the moon in its orbit around the Earth passes through the Earth’s shadow opposite the sun, known also as the umbra shadow. This can only happen during a full moon when our planet lies in a line between the sun and moon.

But this doesn’t occur every time there’s a full moon because the moon’s orbit around the Earth is tilted by 5 degrees to the Earth’s orbit around the sun. Most of the time the full moon misses the Earth’s shadow. It either passes above or below it. Not this time, though! This Sunday evening the moon forges right into the umbra and we’re in for some real eye candy!

Right around 9:34 p.m., you’ll start to see the lower left side of moon’s disk begin to darken, and by 10 p.m. you’ll really begin to see a big bite being taken out of the moon. You can’t help but notice that the shadow has a circular edge to it as it creeps across the lunar surface. Ancient Greek scientists saw this circular shadow as proof the Earth was round. Now they were really ahead of their time!

From 10:41 until 11:43, the moon will be totally eclipsed but will still be visible. It could take on a bright orange hue or it might be bloody red. No one can really predict what hue the eclipsed moon will take on. Only the shadow knows — the Earth’s umbra shadow, that is.

The umbra shadow opposite the sun is not totally dark because some of the sun’s light manages to get to get to it through our Earth’s atmospheric shell. The sunlight that does get through is bent and strained as it comes through our atmosphere. All the blue and yellow components of the sun’s light are scattered away, leaving just reddish parts of the sun’s light.

The shade of the red light reaching the moon depends on the combined atmospheric conditions of where the sunlight passes through on its way to the moon. That makes it impossible to know exactly what shade of red or orange the eclipsed moon will take on but it’s also part of the fun of a total lunar eclipse.

No matter what shade of red the moon takes on, it’ll be beautiful and perfectly safe to look at. Unlike solar eclipses, you don’t have to look through any special glass or anything — although anytime you stare at full moon it could affect you … maybe even make you a little loony!

A pop culture term that’s emerged in the last couple of years is to refer to a totally eclipsed moon as a blood moon. It’s not based of anything technical or astronomical and it certainly doesn’t suggest that you should be afraid of lunar eclipses.

During totality you’ll see the moon pass in front of or eclipse several stars. Not only does the moon rise in the east and set in the west just like the sun, just but it also takes a much slower eastward migration among the background of stars as it orbits the Earth every month.

Normally it’s hard to see these stellar eclipses because of the brightness of the moon but with the moon going through a one hour “power failure” they’re a lot easier to see. Also, because the moon has no atmosphere, you’ll see stars popping out of view on the eastern side of the moon’s disk and popping into view on the western side.

Not only will we have a lunar eclipse or blood moon this weekend, the full moon month is also considered a supermoon. That term is somewhat arbitrary. The full moon will physically be a little closer to Earth than it usually is, but honestly not all that much. With keen visual skill and imagination, the moon tonight will appear a little larger than average. The supermoon is actually an astrology term coined by Richard Nolle back in 1979.

No matter if you call it a lunar eclipse or a blood moon or a bloody supermoon, it’ll be a wonderful experience and one that’s worth losing a little sleep over!

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