By Tom Burns
March 9, 2014
Sometimes I thank my lucky stars that I get to write this column. If I didn’t, I’d have to go door to door to tell you that our hemisphere will soon be graced by a total eclipse of the moon. Look for it on Tuesday, April 15, very early in the morning.
A total lunar eclipse happens when Earth is positioned directly between the sun and the moon. Earth’s shadow blocks the light from the sun that normally illuminates the full moon.
The main event starts at about 2 a.m. At that time, the moon will pass into the Earth’s shadow and slowly disappear over the next hour. It will look like a giant monster is taking larger and larger bites out of a cosmic cookie.
By 3:08 a.m. the entire disk of the moon will be obscured. At that point, the full moon will glow a dark, coppery red, like a bloody fingerprint in the sky. It will remain in that state of total eclipse until 4:23 a.m. for about 1 1/4 hours. The middle of totality occurs at 3:46 a.m. – the point at which the moon will be at its darkest.
Luna will begin to reappear at about 4:45 a.m. Over the next hour or so, the disk of the moon will appear to get larger and larger. By 5:32 a.m., the bright disk of the full moon will have returned, and the eclipse will be over.
Luna will be pretty high in the sky for the entire eclipse, but make sure that trees or buildings won’t block your view.
What a pleasure it is to describe an astronomical event that doesn’t require a telescope as big as a corn silo to see and doesn’t demand that you drive to the dark, rural skies of Middle-of-Nowhere, Ohio. The binoculars you were born with, your own two eyes, are all you need.
However, binoculars can be quite handy because they help you to see details like craters and lunar “seas” disappear slowly as the face of the moon is obscured.
Please note that we are not having a public program for the event at Perkins Observatory. Assuming it’s clear, you can see the eclipse just as well from your backyard.
If it happens to be cloudy that morning, don’t despair. Eclipses of the moon often come in pairs. We’ll get another chance on Oct. 8.
Many ancient cultures honored the moon as a god of fertility, a giver of life on whom humans depended for the continuance of their race and the success of their crops. Her disappearance during an eclipse was truly a terrifying event. As they saw the bloody moon, they imagined that it was their pearly white goddess shining through the belly of the beast.
It looked to our forebears like a giant, invisible monster had unhinged its jaws and was slowly swallowing the moon. The monster is often depicted as a dragon, a snake, a wolf, or some other prehistoric or mythic creature. Thank goodness the goddess Luna doesn’t taste very good. The monster always regurgitated it.
Some cultures didn’t depend on that. They threw spears, shot arrows, beat on drums, and yelled insults at the monster to frighten it away.
And why did humans engage in those rather odd practices for 10,000 years? It always worked. The monster always upchucked their goddess. Why mess with success?
Of course, we know better now. The moon is obscured because Earth gets between the moon and the sun. As the moon moves deeper and deeper into the darkest part of the Earth’s shadow, called the umbra, the bright disk of the moon shrinks to a thinner and thinner crescent. At totality, the moon is totally covered by the umbra.
So why doesn’t the moon completely disappear? The weird, red glow is caused by a process called atmospheric refraction. Some of the sun’s light slips though. Earth’s atmosphere acts like a giant lens, bending a little of the sun’s light around the Earth and onto the moon’s surface. The blue light is scattered into the atmosphere. (That process is, of course what makes the sky blue.) The red light gets through and makes the moon red.
The shade of red is determined by the amount of natural pollution currently in our atmosphere. Dust and ash kicked up by volcanic eruptions and smoke from forest fires are the main causes. It goes to show that even the worst natural disasters are good news for somebody. Horrible natural events turn the moon a deep, beautiful red. A relatively clear atmosphere, free of those natural pollutants, will allow more light through and light up the moon with a bright coppery color.
There is something eerie, unworldly, about a lunar eclipse. The experience takes you back to your most primal ancestral fears. During the deepest part of the eclipse, if your heart and mind are open, you will be transported to the African savannah or the mountains of India or the forests of Germany 10,000 years ago.
I know the scientific explanation of an eclipse. But as the moon goes into full eclipse and nothing is left but a blood-red orb, I think I’ll heave a spear or two, just in case.
Tom Burns is the director of Perkins Observatory. He can be reached at firstname.lastname@example.org.