SRU, nation prepare to witness total eclipse of the sun
Aug. 10, 2017
SLIPPERY ROCK, Pa. - Centuries ago, from the edge of his small hut, a Chinese farmer watches the morning sky anxiously. If the astronomers had predicted correctly, a hungry dragon was about to swallow the sun.
Beginning in 1375 BCE, countless theories for the sun's disappearance erupted from all corners of the globe. Quarreling gods, ravenous monsters and omens of death became a few foreboding explanations while magic, miracles and even peace accounted for the darkness' astounding beauty.
Little did viewers know then that the sun's temporary vanishing act was the result of a natural, cosmic phenomenon - a total solar eclipse.
The United States will experience that very same type of "blackout" that has inspired fear and wonder since the ancient Greek poet Archilochus wrote, "There is nothing beyond hope, nothing that can be sworn impossible, nothing wonderful, since...night from midday, hiding the light of the shining sun," April 647 BCE.
The Aug. 21 event will be visible in totality across an entire band of the country, but will only be visible in other countries as a partial eclipse. The previous time a total solar eclipse was visible across the entire contiguous U.S. was June 8, 1918.
At SRU, the eclipse is expected to be visible from 1:10 - 3:45 p.m. with the peak time at 2:35 p.m. In our area, the moon is projected to cover approximately 79 percent of the sun. Long-range weather forecasts call for sunny skies with the temperature in high 70s; perfect viewing conditions.
A solar eclipse occurs when the moon passes between Earth and the sun, totally or partly obscuring the sun from Earth's view. A total solar eclipse occurs when the moon's apparent diameter is larger than the sun's, blocking all direct sunlight. The outcome is day turning into dusk, a drop in temperature and a halo of light where the sun used to be, all transpiring within an average two-and-a-half-minute span.
"The sun, new moon and Earth have to be in perfect alignment. This only occurs when the moon is situated one-half of a degree off the Earth's orbital path around the sun," explained Krishna Mukherjee, assistant professor of physics and engineering at Slippery Rock University.
In simpler terms, a total solar eclipse is a rare but magnificent occurrence. In fact, the anticipated spectacle is so unique that it has been hailed by its adoring fans as the "Great American Eclipse."
As the first total solar eclipse to cross the U.S. skyline in nearly 100 years, the event offers both fascination and startling accessibility to its citizens as an estimated 12.25 million Americans will be caught in the 70-mile-wide path that will span 14 states coast-to-coast. An additional 1.85 to 7.4 million are expected to make the journey to a totality destination on eclipse day.
Beginning at approximately 9 a.m. PT just north of Depoe Bay, Oregon, the eclipse will begin its tour across the continental U.S., with Bulls Bay, South Carolina it's final destination at around 4 p.m. ET.
Those outside the totality line, which includes the remainder of the contiguous U.S., the remainder of North America, along with parts of South America, Africa and Europe, will witness only a partial eclipse in varying degrees based on location.
With only partial coverage of the solar disk, this will mean more exposure, particularly from the corona, an aura of plasma that surrounds the sun and other stars and extends millions of kilometers into space.
"In the past, people thought the corona was a glow around the sun, but now astronomers have discovered that its temperature is over a million degrees Kelvin, threaded with magnetic field lines originating from the sun," Mukherjee said.
"The density of the plasma is so low that during those two minutes of totality when only the corona is visible, it does not harm the eyes. Here in Pennsylvania, however, we are not witnessing totality, so viewers should take extreme precaution."
According to Mukherjee, Pennsylvanians can just as fully participate in the solar sightseeing experience as those in totality, albeit with the proper equipment. Glasses, telescopes or binoculars, each fitted with solar filters and dark lenses, are required accessories and should not be of a homemade variety.
"Normal sunglasses will not offer the required protection," Mukherjee said. "I can't stress that enough. Take the extra step and get a proper pair of viewing glasses in order to protect the eyesight of yourself and your loved ones."
"Eclipse" glasses remain especially inexpensive and accessible to the public, however viewers are urged to exercise caution when purchasing. According to the American Astronomical Society, a number of scams and uncertified products have entered the global market due to the widespread popularity of the event. Buying defective glasses can lead to retinal damage and blindness.
According to the AAS, it's important to purchase glasses that have an "ISO" label. The acronym for the International Organization for Standardization, an independent organization that writes safety and quality standards for all kinds of things, including eyewear, health care, food production and more based on a broad consensus of the scientific community.
ISO-approved "eclipse" glasses must meet certain safety requirements, including:
-No more than 0.00032 percent of the sun's light may be transmitted through the filters.
-The filters must be free of any defects, such as scratches, bubbles and dents.
-Handheld viewers must be large enough to cover both eyes.
-Labels on the viewers or packaging must include the name of the manufacturer, instructions for safe use and warnings of the dangers of improper use.
For a complete list of reputable vendors of "eclipse" glasses, solar filters and viewers, visit: https://eclipse.aas.org/resources/solar-filters. Other important eclipse viewing safety instructions are available at: https://eclipse2017.nasa.gov/safety.
For those unable to view the eclipse in person, NASA will be hosting an "Eclipse Megacast." The show will broadcast on NASA TV as well as Ustream and YouTube.
"This event is a phenomenon to behold," Mukherjee said. "Everyone should watch how the sun's reduced light affects our landscape and the enhanced contrast between light and shadow which will make for great photographic opportunities.
"As James Fenimore Cooper said so beautifully, 'I've traveled the world and sailed the seas, but never have I beheld any spectacle which so plainly manifested the majesty of the Creator, or so forcibly taught the lesson of humility as a total eclipse of the Sun.'"
MEDIA CONTACT: Maizee Zaccone | 724.738.2091 | mxz1016@sru.edu