Written by Tony Phillips
Science at NASA
Washington, D.C. – Sunsets are always pretty. One sunset this month could be out of this world. On Thursday, October 23rd, the setting sun across eastern parts of the USA will be red, beautiful and … crescent-shaped.
“It’s a partial solar eclipse,” explains longtime NASA eclipse expert Fred Espenak. In other words, the New Moon is going to ‘take a bite’ out of the sun.A total eclipse is when the Moon passes directly in front of the sun, completely hiding the solar disk and allowing the sun’s ghostly corona to spring into view.
A partial eclipse is when the Moon passes in front of the sun, off-center, with a fraction of the bright disk remaining uncovered.
The partial eclipse of October 23rd will be visible from all of the United States except Hawaii and New England. Coverage ranges from 12% in Florida to nearly 70% in Alaska. Weather permitting, almost everyone in North America will be able to see the crescent.
The eclipse will be especially beautiful in eastern parts of the USA, where the Moon and sun line up at the end of the day, transforming the usual sunset into something weird and wonderful.
“Observers in the Central Time zone have the best view because the eclipse is in its maximum phase at sunset,” says Espenak. “They will see a fiery crescent sinking below the horizon, dimmed to human visibility by low-hanging clouds and mist”.
Warning: Don’t stare. Even at maximum eclipse, a sliver of sun peeking out from behind the Moon can still cause pain and eye damage. Direct viewing should only be attempted with the aid of a safe solar filter.
During the eclipse, don’t forget to look at the ground. Beneath a leafy tree, you might be surprised to find hundreds of crescent-shaped sunbeams dappling the grass. Overlapping leaves create a myriad of natural little pinhole cameras, each one casting an image of the crescent-sun onto the ground beneath the canopy. When the eclipsed sun approaches the horizon, look for the same images cast on walls or fences behind the trees.
Here’s another trick: Criss-cross your fingers waffle-style and let the sun shine through the matrix of holes. You can cast crescent suns on sidewalks, driveways, friends, cats and dogs—you name it. Unlike a total eclipse, which lasts no more than a few minutes while the sun and Moon are perfectly aligned, the partial eclipse will goes on for more than an hour, plenty of time for this kind of shadow play.
A partial eclipse may not be total, but it is totally fun.
See for yourself on October 23rd. The action begins at approximately 6:00pm on the east coast, and 2:00pm on the west coast. Check NASA’s Eclipse Home Page for viewing times near your hometown.