There’s an ‘impossible’ lunar eclipse happening Wednesday (8)

By Jessica Orwig From Business Insider

On Wednesday, Oct. 8, you will get the chance to see one of the rarest types of lunar eclipse, called a selenelion or horizontal eclipse. But you have to be quick — the crazy light trick will only be visible for a short period between two and nine minutes.

Most of the time, a lunar eclipse will occur well before sunrise, but that won’t be the case on Wednesday morning. The Earth will pass between the sun and moon, eclipsing the moon in the process, which will begin at 6:25 a.m. EDT and last through sunrise, but only on the east coast.

That means during a brief window people on the east coast of the country will be able to see the sun rise and moon set at the same time. This rare event is referred to as a selenelion or horizontal eclipse.

There are plenty of times throughout the year when both the sun and moon are visible during the day. But during a lunar eclipse the chance to see both the sun and moon simultaneously is extremely rare. This is because, geometrically speaking, this kind of phenomenon should not be possible.

A lunar eclipse is one of the only times that the moon and sun are exactly 180 degrees apart on Earth’s sky, which means that right after the moon sets, the sun should rise, making it technically impossible to see both at once.

But a simple trick of the light changes everything, and as a result, crafty observers can see this wild, and otherwise impossible, event.

Observers in Australia, western Asia, islands in the Pacific Ocean, and much of North America will get the chance to observe the lunar eclipse. However, only a few regions on Earth will have the chance to see the selenelion, so check to see if your sunrise and moonset times overlap tomorrow morning.

Because Earth’s atmosphere refracts, or bends, light at a certain angle near the horizon, it creates an optical illusion that makes both the sun and moon appear slightly higher in the sky and therefore less than 180 degrees apart. As a result, we get a tiny window where we can see both celestial orbs simultaneously.

Unless you are atop a mountain or sailing in the middle of the ocean, however, you might be hard pressed to catch this trick of the light. You need to be in a spot where you can clearly see both the east and west horizons. But if you are in such a spot, you’ll catch an especially rare sight of a setting eclipsed moon with a rising sun.

Furthermore, we are in a rare series of lunar eclipses. This lunar eclipse is the second of a series of four consecutive total lunar eclipses. The first total lunar eclipse was April 15, 2014, and the next two will be on April 4 and Sept. 28 of next year. This series of total lunar eclipses is rare and the next series of four consecutive total lunar eclipses will not occur until the year 2032.

Sky watchers in the US will see the moon turn a beautiful shade of celestial red and maybe turquoise, too, according to this video from Science@NASA

IMAGES:

Tomruen Lunar eclipse April 15, 2014 as observed in California

Bogdan A sunrise. Now imagine turning 180 and seeing a moon-set. That’s “selenelion.”

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