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 be graced by a total eclipse of the moon, the fourth – and best – in the past two years or so.
Look for it during the night of Sunday, Sept. 27, from 9:07 p.m. Eastern until 12:27 a.m. Eastern, which is technically Monday, Sept. 28.
You’d better try to catch this one. The next total lunar eclipse won’t happen until 2018, and that one won’t be very good from central Ohio.
A 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.
Starting at 9:07 p.m., 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 10:11 p.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 for over an hour. The middle of totality occurs at 10:47 – the point that the moon will be at its darkest.
Luna will begin to reappear at 11:22. Over the next hour, the disk of the moon will appear to get larger and larger. By 12:27 a.m., the bright disk of the full moon will have returned, and the eclipse will be over.
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.
Please note that we are not having a public program for the event at Perkins Observatory. Assuming it’s clear, you can see this one very well indeed from your backyard.
Luna will be high in the sky for the entire eclipse, but make sure that trees or buildings don’t block your view of the moon.
Binoculars are useful because they help you to see details like craters and lunar “seas” disappear slowly as the face of the moon is obscured. But the binoculars you were born with — your own two eyes — will produce a spectacular view of the eclipse.
Many ancient cultures honored the moon as a god of fertility, a giver of life on whom humans depended for the continuance of the race and the success of their crops. Her disappearance during an eclipse was truly a terrifying event.
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 cookie monster. 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 scare 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 change the moon to a deep, beautiful red. After a major volcanic eruption, the moon turns a deep ashen gray and almost disappears.
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 and joys. 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 what happens during an eclipse. But as the moon goes into full eclipse and nothing is left but a blood-red orb, I think I’ll toss a spear or two, just in case.
Tom Burns is director of the Perkins Observatory in Delaware.