A photo of the first total lunar eclipse of 2014 taken from Arizona
Credit: Ron Delvaux via The Virtual Telescope Project

Observers of Wednesday (October 8) morning’s Moon may see a rarity:  a total eclipse of the moon and the rising sun simultaneously. The little-used name for this effect is called a “selenelion.”

During a lunar eclipse, the sun and moon are exactly 180 degrees apart in the sky in an alignment called a “syzygy” (an excellent Scrabble and Words With Friends word).

It’s a bit of an atmospheric trick that seems, like most good tricks, to be impossible. Earth’s atmospheric refraction causes the images of both the sun and moon to “lift” above the horizon. That means that to our eyes, we can see the sun for several extra minutes before it actually has risen and the moon for several extra minutes after it has actually set. Excellent trick.

This coincides with the full moon of October on the 8th which we tend to think of as being a nighttime event, although it often reaches its fullest during our daylight hours when it isn’t visible to us. This month it occurs around sunrise for the east coast.

For many of us east of the Mississippi River, we will have a chance to observe this, weather permitting. It is a short window of opportunity – about 2 to 9 minutes (depending on your location) with the possibility of simultaneously seeing the sun rising in the east while the eclipsed full moon is setting in the west.

The eclipse will happen when the full moon passes directly through earth’s shadow.  According to the wonderful earthsky.org website, if you live in the Americas or Hawaii, the total eclipse happens before sunrise October 8, and while the total part of the eclipse will last about an hour, the entire event will last more than three hours. (In the Central time zone, that means the partial lunar eclipse will be visible beginning around 4:15 a.m and become total at 5:25 a.m., end at 6:24 a.m., with another partial eclipse to follow at 7:34 a.m. Central time.

Our full moon also occurs on October 8. This particular full moon is usually called the Hunter’s Moon or Blood Moon and the time between moonrises is shorter than usual for several consecutive nights around the full moon, bringing bright moonlight from early evening until dawn on those nights. The term Blood Moon has another meaning, but a full moon almost always has a reddish appearance during a total lunar eclipse.

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