A glimpse at the 2017 solar eclipse [excerpt]

The United States mainland has not experienced a total solar eclipse in 38 years, and the upcoming 2017 eclipse promises to be the most-watched total eclipse in history. Why are millions of Americans travelling to witness this event?

In the following excerpt from Eclipse: Journeys to the Dark Side of the Moon, author Frank Close gives us a glimpse into the allure of the total eclipse.

Anyone who has experienced the diamond ring effect that heralds the start of a total solar eclipse will tell you that it is the most beautiful natural phenomenon that they have ever seen.

That this marvel happens is thanks to a cosmic coincidence: the sun is both 400 times broader than the moon and 400 times further away. This makes the sun and moon appear to be the same size. So if the moon is in direct line of sight of the sun, it can completely and precisely block it from view.

A total eclipse of the sun happens about once every 18 months. As the moon moves slowly across the face of the sun, it casts a shadow on the earth’s surface, about 100 miles in diameter. As our planet spins in its daily round, the moon’s silhouette rushes across land and sea at about 2000 miles an hour. The moon is totally eclipsed on the average twice every three years. The event lasts for several hours and can be seen by everyone on the night-side of the earth, weather permitting. Even under cloud, the darkening would be apparent. In addition to these total eclipses there are partial eclipses of the moon, which happen about every eight months. Totality is rare, and most people pass their whole lives without seeing one.

The propaganda benefit of associating eclipses with singular events touches our psyche profoundly. If a total eclipse of the sun occurred in the homelands of a primitive tribe, it would be a singular event, long remembered and passed down in folklore. Partial solar eclipses, however, might occur half a dozen times in a lifespan. Most of those partial eclipses won’t dim the light, and might escape notice entirely other than by sages, witch-doctors, and astrologers. Total eclipses, by contrast, would create fear and panic when the source of light, heat, and life itself was suddenly blotted out. Minutes later there would be relief as daylight returned. Reprieved by the gods, the audience would be ripe for exploitation by charlatans, or by those ‘in the know’.

[image error]Resources provided by NASA.

On 21 August 2017, up to 200 million people will gather in a narrow belt across the USA, from Oregon to South Carolina, to witness the most watched total solar eclipse in history.

There is a slow build-up to the totality show, as the moon gradually covers the sun, which becomes a thin crescent as twilight falls. As the climax approaches, excitement mounts. The temperature drops, and then, in the west, a wall of darkness like a gathering storm rushes towards you. This apparition is the moon’s shadow.

In an instant you are enveloped by the gloom. The last sliver of sun disappears and, as from nowhere, a diamond ring flashes around a black hole in the sky, vibrant, like a living thing. For those beneath the shadow as it passes, the sounds of animals cease, and life seems in suspended animation as for a few minutes night comes to the dome of the sky directly overhead, and covers the land from one horizon to the other. Look up myopically, and you would see stars as if it were normal night, accompanied by an awesome sight: that inky circle, surrounded by shimmering white light, like a black sunflower with the most delicate of silver petals.

One watcher has described it to me as like ‘looking into the valley of death with the lights of heaven far away calling for me to enter’. After the thrill of an eclipse you can’t wait to do it again, but wait you must until that exquisite alignment of sun, moon, and earth comes around once more. When it does, you must go to the thin arc where the moon’s shadow momentarily sweeps across a small part of the globe. For a total eclipse is only visible at special places on earth; a mere 0.5% of the earth’s surface is totally obscured by the moon’s shadow for just a few minutes, while the remaining 99.5% sees either a partial eclipse or nothing at all.

Anyone who hasn’t experienced totality might struggle to understand why people are prepared to adventure to the far side of the earth, by plane, ship, even on the hump of a camel, to be there. I didn’t anticipate that I would spend the latter years of my life planning expeditions throughout the globe to watch them.

Featured image credit: “Totalsolareclipse2001cmp” by Fred Espenak . Public Domain via Wikimedia Commons.

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