What makes the Oct. 8th lunar eclipse so special? It's an "impossible" occurence

Tuesday, October 7, 2014

The moon turns red and orange during a total lunar eclipse. Learn why this happens in the next slides.

The geometry of a lunar eclipse. When the moon passes into the Earth's umbra (shadow), it will darken and redden as sunlight must pass through Earth's atmosphere to reach it.

Phases of the eclipse. Light wavelengths are scattered by Earth's air molecules, and when the sunlight has passed through the atmosphere, only red wavelengths remain.

The eclipse will be visible in its entirety over the Northern Pacific. North America viewers will experience the eclipse after midnight on Wednesday, October 8th, 2014.

Local times for the closing stages of the lunar eclipse on October 8th, 2014.

$Diagram showing displacement of the Sun's image at sunrise and sunset. This is due to atmosphere refraction: light being bent by our atmosphere's moisture and gases (e.g. air).$

Total eclipse phases as it passed north of the Earth's shadow on October 8, 2014. Universal Time.

During a selenelion, the reddened light that reaches the moon comes from all sunrises and sunsets happening simultaneously on the Earth.

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What makes the Oct. 8th lunar eclipse so special? It's an "impossible" occurenceThe moon turns red and orange during a total lunar eclipse. Learn why this happens in the next slides.

Photo/NASA

On Wednesday early morning, those watching the sky in North America will be able to witness the most unique total lunar eclipse yet. Though lunar eclipses happen twice a year, you might be upset to miss this one, as this rare type of eclipse will occur while the Sun is still up.

Geometrically speaking, that is impossible.

The typical lunar eclipse happens when the Sun, Earth and moon are all aligned 180 degrees apart from each other in the sky. When this happens, the Earth casts a shadow onto the moon, so the Sun should not be visible at all if you can still see the moon. How can this be? It's one, big cosmic illusion.

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This type of eclipse is called a selenelion (or "horizontal eclipse"), where a viewer can see both the total lunar eclipse and the sun at the same time. It happens because of the Earth's atmosphere's tendency to refract, or bend, light slightly. Our atmosphere is filled with moisture and gases that can bounce light (like air), and astronomical objects tend to always appear higher in the sky than in reality. So as the Sun and moon appear to be hovering just above the horizon on opposite sides of the sky, those are not exactly their true geometric locations.

Nope, they are still aligned 180 degrees as usual.

The illusion, however, will be rare and wondrous to behold. All those in North America should be able to view the moon turn blood red, and those East of the Mississippi will have a chance to observe the selenelion firsthand. Those in the Eastern states should be able to observe sunrise during the eclipsed full moon for about 2-9 minutes, depending on your location.

Those in the Western states, however, have the advantage of seeing the eclipse throughout the darkness of night, enhancing the spectacle. While not quite as rare as the selenelion, it should still be magnificent.

The eclipse will begin at about 1:17 a.m. PT, or 4:17 a.m. EST and last for about two and a half hours.

Local Times for the closing stages of the lunar eclipse:

Learn more about a lunar eclipse here:

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Will you stay up late (or wake up super early) to see this rare selenelion? Let us know in the comments below.