A rare treat for Arctic sky-gazers: a lunar eclipse tomorrow morning

The lunar eclipse of April 15, 2014, photographed from California. (PHOTO BY ALFREDO GARCIA JR., CREATIVE COMMONS)

If people often accuse you of being a star-gazer, you might want to get up early Oct. 8 to catch a glimpse of the huge “blood moon” that often results from a total lunar eclipse.

A full lunar eclipse will reach totality at 6:25 a.m. eastern time early Oct. 8 in eastern North America, said a Sept. 18 news release from the National Aeronautics and Space Administration.

A lunar eclipse occurs when the earth passes between the sun and the moon, casting a shadow on the moon.

The shadow grows as the earth moves to completely block the line of sight between the sun and moon, reaching totality.

As light from the sun passes through the earth’s atmosphere, it bends — or refracts — and scatters.

Colours of light with longer wavelengths — such as red — are not as easily scattered, so they make it to the moon’s surface for us to see.

This same principle makes sunsets and sunrises appear red.

The hue of red during an eclipse depends on the amount of dust in the atmosphere from, for example, volcanoes, NASA said.

With enough dust, a “lunar eclipse can turn such a deep red that the moon looks almost black. That’s not the case this time, however.”

If you need an extra incentive to get up before sunrise, the lunar eclipse will coincide with what an American astronomy lecturer and writer says is technically impossible.

Joe Rao, an instructor at New York’s Hayden Planetarium, writes on space.com that sky-gazers may see a sunrise and a moonset during an eclipse simultaneously, “an extremely rare cosmic sight.”

This event is called a “selenelion”.

But if the earth is between the sun and the moon — all three celestial bodies forming a straight line — how can this be?

“Thanks to the Earth’s atmosphere, the images of both the sun and the moon are apparently lifted above the horizon by atmospheric refraction,” Rao writes.

“This allows people on Earth to see the sun for several extra minutes before it actually has risen and the moon for several extra minutes after it has actually set.”

Weather permitting, and depending on location, this impossibility may last from two to nine minutes, Rao writes.

Residents of western Canada have an even better chance to see the eclipse because the moon will be higher in the sky while totality occurs, according to NASA, between 4:25 a.m. and 5:24 a.m. mountain time.

“I encourage everyone, especially families with curious children, to go out and enjoy the event,” NASA eclipse expert Fred Espenak said in the release.

“It promises to be a stunning sight.”