Once upon a time, there was a Hindu demon named Rahu. He wanted to live forever, so he disguised himself as a god and set out to steal an elixir of immortality. The sun and moon saw what Rahu was doing and reported the incident to the god Vishnu, who chased down the demon and cut off his head. However, a drop of potion touched Rahu’s tongue, granting his head (and only his head) immortality. The demon was angered by the sun and moon’s tattling and spent the rest of his days chasing them. Occasionally, he catches one or the other and tries to eat it, which results in a solar or lunar eclipse. Fortunately, the demon doesn’t have a body, and the sun or moon escapes out the throat as Rahu attempts to swallow.
Ancient Hindus weren’t the only ones with a story. The Chinese blamed a sun-eating dog and sounded gongs and firecrackers to scare it away. Vikings blamed a hungry wolf, while those in Vietnam blamed a frog. And regardless of the creature at fault, nearly every civilization, from the Aztecs in Mexico to Joseons on the Korean Peninsula, stopped in their tracks and anxiously waited for the event to pass.
Today we know the real reason for a solar eclipse and can accurately predict its time and location. Once every year or two, the moon passes between the sun and the earth at just the right location to cause a large moon shadow to sweep across the land. Most places see the event as a partial eclipse, but a thin strip in the middle of the shadow witnesses “totality” as the moon briefly covers the entire width of sun. Day turns to night. Stars appear. Birds stop singing. No wonder the ancients were frightened!
Total solar eclipses are rare in the United States. There have only been 20 since the signing of our Declaration of Independence, and the last time the entire country saw one was 1918. On Monday (August 21, 2017), another solar eclipse will track across America from Oregon to South Carolina with a zone of totality cutting through the heart of our nation. Here in Central Ohio, the moon will block 86% of the sun at 2:30 pm.
While this is an exciting event, there are important safety precautions.
The sun is REALLY bright, and even a tiny glint poking around the edge of the moon can damage the eye and result in permanent vision loss. To keep you safe, NASA has teamed up with the American Astronomical Society and the American Academy of Ophthalmology to bring you some important viewing tips:
- Except when the eclipse is briefly in “totality,” don’t look directly at the sun without special eye protection. Eclipse glasses and handheld solar viewers should be compliant with the 2015 ISO 12312-2 international safety standards. Sunglasses (even very dark ones) are NOT safe. The AAS maintains a list of reputable brands of eclipse glasses and solar viewers.
- Always inspect eclipse glasses before viewing. Don’t use if the lenses are scratched or damaged.
- Supervise children when viewing a solar eclipse. If they are too young to follow directions, they are too young to safely enjoy direct observation of the event.
- Cover eyes with eclipse glasses BEFORE looking at the sun and do not remove until looking away.
- Do not look at a partial eclipse through an unfiltered camera, telescope, binoculars or any other optical device, and do NOT use eclipse glasses to look through them. These viewers concentrate sunlight and will damage the eclipse glasses (and your eyes!)
- If you are in the path of totality, remove your eclipse glasses ONLY when the sun is 100% covered and put them back on before the sun reappears. Please note: Ohio will NOT experience totality, and you should use eclipse glasses to view the entire event.
- If you wear eyeglasses, leave them on and place the eclipse glasses over them.
- An alternate method for safely viewing a partial eclipse is pinhole projection.