NOTE: A Twitter exchange recently revealed that certain members of a small subset of science writers who were humanities majors, also have a shared taste for classic mystery writers. So they decided to write a series of cross-linked posts on their respective blogs about the science of classic mysteries. Links to other posts in the series can be found at the end of this post.
"The sun was about to have its eye put out by the murdering moon." - Dark Nantucket Noon
"The sun was about to have its eye put out by the murdering moon." - Dark Nantucket Noon In Jane Langton's classic mystery, Dark Nantucket Noon, a young heartbroken poet named Kitty braves a possible unpleasant encounter with her ex-lover to travel to Nantucket in order to view a total solar eclipse. "It was the two-and-a-half minutes of totality that she had come to see, when the light of the sun would be completely blocked out by the moon, and the sky would darken, and the solar corona would appear."
Kitty is an "eclipse chaser," or "umbraphile," and she's far from alone in her fascination. Many astronomy buffs travel great distances, to remote locations, in order to witness this rare event.
A total solar eclipse, as its name implies, is what happens when the Moon passes between the sun and the Earth, when the Moon is closest to Earth in its orbit. Historians usually cite June 15, 763 BC as the earliest record of such an event, based on an ancient Assyrian text. The most recent total solar eclipse occurred on July 11, 2010, and we won't see another until November 13, 2012.
A partial eclipse, in contrast, means that the Sun and Moon are not perfectly in conjunction, so the Moon can't completely block out the sun. The most recent partial eclipse happened on November 25 of this year, mostly visible in the southernmost part of the world.
During an annular eclipse, you get the critical conjunction, but the Moon is too distant from the Earth in its orbit to completely block out the sun. Instead, you get a very bright ring around the moon. This will next occur on May 20, 2012.
Langton's novel opens with one of the finest descriptions of a total solar eclipse in modern literature, with passing references to the solar corona, Baily's beads (notably seen in the opening credits of the TV show Heroes), shadow bands, and the diamond ring effect, "the flash of red light at the very end" - all very real phenomena that occur during an eclipse.
There's even a reference to how scientsts converged on Nantucket's Maria Mitchell Observatory to "photograph the eclipse... and make spectrographic studies of the solar prominences." After all, it's one of the best opportunities to study the sun's outer layer (solar corona).
Not surprisingly, Langton herself witnessed the March 17, 1970 total solar eclipse in Nantucket, which lasted 3 minutes and 28 seconds over Mexico; in Nantucket, totality would, indeed, as she writes, have lasted a mere two minutes or so.
The longest recorded period of totality in recorded history - 7 minutes and 29 seconds - won't occur until July 16, 2186, although during the total solar eclipse of June 30, 1973, passengers aboard the Concorde flew directly along the path of the Moon's umbra, and thus were able to prolong totality for nearly 74 minutes.
Only someone who had witnessed such an event firsthand could evoke the experience so well:
"A tiny nibble had been taken from the lower right hand side.... The bite that was being taken by the hungry moon was growing bigger....
That last sentence seems to describe shadow bands, or flying shadows, which appear just before and after a total eclipse. There's a similar phenomenon that happens during partial eclipses called anisotropy. In that case, the angle of the sun as its light hits objects casts shadows with a narrow penumbra in one directon, but a very broad one in the other direction.
Langton also mentions, in passing, that Kitty has brought along a "photographic plate... wrapped carefully in a cotton kerchief." This is to allow her to "view" the eclipse indirectly, without staring directly at the sun. Doing so, as most amateur astronomers know, can permanently damage the retina and cause blindness in mere fractions of a second. You probably won't even feel it until it's too late.
And don't think sunglasses, the lens of a telescope, binoculars or camera viewfinder will save you, either. You really need specially designed filters, or a means of indirect project, like a homemade pinhole camera.