A total lunar eclipse will occur early Friday when a ‘Blood Moon’ may appear over Philly

It will get mighty dark up that way, but the best viewing during the total eclipse of what will become the sanguinarily named “blood moon” might well be from the moon itself.

Through a perfectly clear sky free of water vapor and unsightly atmospheric muck, during totality you would see the Earth obscure the sun, and a spectacular ring of reddish, glowing light would surround our planet, says Harry J. Augensen, director of the Widener University planetarium.

We don’t see total lunar eclipses often ― we’ll have to wait four years to see the next one around here — but they occur on average about twice a year, and experts have predicted the day is not all that far away when lunar tourism will be a reality. Not that it would be cheap.

In the meantime, the earthbound in Philly and the rest of the Western Hemisphere should get a decent show, weather permitting, and providing you don’t mind surrendering more sleep during a week in which you likely already have lost some.

The sun, Earth, and moon will align, and during a six-hour period the shadow cast by our planet will slowly cover the moon in its entirety, then just as slowly allow the moon to reemerge as its cratered, full-faced self.

The event begins just before midnight Thursday, when the first trace of Earth’s shadow will encroach upon the moon, which will be at 99.98% fullness. But don’t expect to see much immediately, NASA officials advise. It will get better.

A partial eclipse should be evident at 1:09 a.m. Friday, when “it looks like a bite is being taken out” of the moon, they said.

Totality begins at 2:26 a.m. — about a half hour before the instant of fullness — and expect the moon to turn a “a coppery red,” and not from embarrassment for being overshadowed by Earth. What you’re looking at, says NASA, is “the glow of all of the sunrises and sunsets on Earth.”

During a total eclipse, the sunlight beaming on the Earth’s atmosphere is refracted, or bent, and the blue hues become more or less bleached out and the light is “reddened,” Augensen said.

Reds and oranges are able to make it through our atmosphere because they have longer wavelengths than the blues, which are easily scattered.

Some of that reddened light “washes” onto the surface of the moon, creating that copper glow, Augensen said.

It’s not exactly the color that the concept of “blood” might evoke, but somehow the term “copper moon” doesn’t carry the same sense of drama.

Totality will last 65 minutes, ending at 3:31 a.m., and that may be a saving grace given the forecast, which calls for the sky over Philly to be about two-thirds cloud-covered.

Given the duration of the eclipse, “Even if it’s cloudy you may still be able to glimpse it if the clouds are scattered,” said NASA scientist Renee Weber.

While the sky forecast “isn’t great,” said Patrick O’Hara, National Weather Service meteorologist in Mount Holly, “it’s certainly possible” that breaks in the clouds could occur.

The partial eclipse will be over at 4:47 a.m.

No, but a telescope or binoculars would enhance the viewing experience during totality.

Of course, surveys indicate that a majority of the local population will be watching the insides of their eyelids during totality.

But, for the record, given that the clocks got nudged forward an hour only a few days ago, your body might think it’s only 1:26 a.m. when totality occurs.