Bucket List Object #8: A Total Solar Eclipse
The #10 sight in our Bucket List for Backyard Stargazers was the glittering globular cluster Omega Centauri. For the sight #9, we suggested you spend an evening watching sunrise over the grand lunar crater Copernicus. Today, we present #8 of our celestial sights for all of us to see before we kick the bucket: a total eclipse of the sun.
Solar eclipses have struck wonder and fear into mankind since prehistoric times. The classical Greek poet Archilochus wrote of an eclipse:
“Zeus, the father of the Olympic Gods, turned mid-day into night, hiding the light of the dazzling Sun; and sore fear came upon men.”
And Mark Twain’s fictional Connecticut Yankee leveraged a solar eclipse to escape a tight spot in King Arthur’s court:
“It got to be pitch dark, at last, and the multitude groaned with horror to feel the cold uncanny night breezes fan through the place and see the stars come out and twinkle in the sky.”
The sudden disappearance of the Sun is, understandably, an unsettling sight. But Zeus has nothing to do with it. A solar eclipse results from the clockwork mechanics of the solar system, as the Moon passes between the Earth and the Sun and casts a shadow across a narrow band of the Earth’s surface, the so-called “band of totality”.
*** From One-Minute Astronomer ***
A concise guide to observing the universe beyond our solar system. Includes tips on equipment selection and observing techniques, along with a tour of dozens of lovely sights in the north and south hemispheres. Click here to learn more…
* * * * * * * * * *
The alignment of the Sun, Moon, and Earth during a solar eclipse
Eclipses are more spectacular because our Moon, which has a diameter 400 times smaller than our Sun, lies almost exactly 400 times closer. This means the disk of the Sun and Moon sometimes overlap exactly, which presents an amazing view of the glowing outer reaches of the solar atmosphere called the chromosphere and corona.
Just outside the narrow “band of totality”, an observer sees the Moon cover only a part of the solar disk; this is a partial solar eclipse. And for some eclipses, the Moon is a little too far from Earth to cover the Sun’s disk exactly, so it leaves a ring of light around the solar circumference. This is an annular solar eclipse… quite different from a total solar eclipse.
But a total eclipse presents, by far, the most memorable experience for any stargazer. As the event unfolds, the Moon’s limb first crosses the Sun’s disk a few hours before totality: without a telescope, the effect is unnoticeable. Then, a few minutes before the peak of the eclipse, the sky and Earth darken, the temperature drops, and animals and insects are startled into their nighttime routine. In the final moments before totality, bright beads of light appear along the limb of the merged disks– these are the so-called Bailey’s Beads caused by the edge of the Sun shining through lunar valleys. As the sun shines through a single valley just before and after totality, a “diamond ring” effect may be visible.
Though it lasts just a few minutes, a total eclipse presents one of the most impressive and shocking sights in nature. Science writer Timothy Ferris, in his book Seeing in the Dark, describes his view of the total solar eclipse of March 2, 1970 in North Carolina:
“Suddenly the sky collapsed into darkness and a dozen bright stars appeared. In their midst hung an awful, black ball, rimmed in ruby red and surrounded by the doomsday glow of the grey corona. No photograph can do justice to this appalling sight: The dynamic range from bright to dark is too great, and the colors are literally unearthly.”
During the brief minutes of totality, you can look towards the sun without eye protection. But keep your wits about you. As the Sun emerges and the diamond ring appears, make sure you look away and watch the rest of the show through the proper solar filters.
It may take centuries for an eclipse to grace an particular point on Earth, so if you want to see one, you may need to pack your bags and travel.
Here’s a link to help you find the next solar eclipse near you.
And if you can’t wait that long, here’s a wonderful video from the BBC of a total eclipse over India…
