Text by Hannah Halusker // Design by Pete Martin
Coming August 21, 2017: “Eclipse Over Clemson”
Clemson University is South Carolina's only top 25-ranked public research university in the path of totality for the 2017 solar eclipse, presenting a rare opportunity to share this extraordinary scientific event with the public at large. Clemson’s main college campus will experience a total solar eclipse at 2:37 p.m. Monday, Aug. 21.
// ONE
In many ancient cultures, people often believed some sort of beast was devouring the sun during an eclipse. Chinese cultures, particularly, thought the beast was a sky dragon eating the sun, bite by bite. They would bang on pots and drums to cause a racket, enough to scare the dragon away. This always worked, too, because eclipses typically last about three hours for any given location.
// TWO
Among the first people to record the frequency of solar eclipses were the Babylonians, starting in 750 B.C. They used archaic water clocks, called clepsydras, to estimate the duration of a solar eclipse. Rather than accounting for time in hours or minutes, the Babylonians tracked how long it took one mana — about one pound — of water to flow out of a hole in the bottom of the clepsydra. The Babylonians increased the amount of mana poured into the clepsydra after the summer solstice to account for the lengthening of night.
// FOUR
Clemson University adjunct professor of physics and astronomy Dr. Donald Liebenberg holds the world record for most time spent in totality. Liebenberg has witnessed and researched 26 total solar eclipses, having spent almost three hours of his life in totality — when the moon fully covers the sun. To give perspective, the phase of totality for one total solar eclipse usually lasts around two to eight minutes.
// FIVE
The solar eclipse of 1919, which passed over South America and Africa, was a legendary eclipse for our understanding of space and time. Published in 1686, Sir Isaac Newton’s laws of motion specify that space and time are inflexible concepts that are not influenced by the presence or absence of other bodies, like planets. Under this theory, light rays travel in a straight path, unaffected by massive bodies that have some innate gravitational force. For more than two centuries, Newton’s laws were the accepted standard in the field of physics, until Albert Einstein’s general theory of relativity was issued in 1915. In Einstein’s theory, paths of motion are influenced by the concepts of space and time. Einstein (shown here) hypothesized that the path of light can be curved by the presence of nearby massive bodies, and that the force of gravity that we observe on Earth is a result of this bending of space and time. Until the solar eclipse of 1919, general relativity was only a theory without concrete supporting evidence. However, photographs of the eclipse taken by Sir Arthur Stanley Eddington, an English astrophysicist, depicted stars from the constellation Taurus that were visible because the sun’s brightness was diminished by the moon. In these images, it was clear that the stars’ light rays were bent by the gravitational force of the sun. Not only did Eddington have photographic proof of the theory of relativity, but when he did the math, he discovered that Newton’s estimates of gravitation predicted only half the shift of light rays that Einstein’s estimates did.
// SIX
Solar glasses, for viewing an eclipse, are not just intended as memorabilia of a once-in-a-lifetime event. The specialty glasses filter out 99 percent of visible light, as well as harmful infrared and ultraviolet rays from the sun. If you look directly at the sun during an eclipse without wearing solar glasses, you can experience varying stages of blindness, with each one affecting a different part of the eye. In stage one — the least severe form — you develop an eye condition called photokeratitis, or sunburn of the eye. Much like sunburn that causes your skin to redden and slough off, photokeratitis causes cornea cells to blister. The eyes take on a sandpaper sensation as they inflame and tear up. Though scary, photokeratitis is temporary and typically heals within a few days.
Stage two of eye blindness — solar retinopathy, or a burn to the retina — has more lasting effects. While most people are healed after three to six months of treatment, others report permanently blurred vision. Partial blindness occurs with even longer exposure to sunlight, particularly to damaging ultraviolet rays. Ultraviolet rays affect the macula of the eye, which is the oval-shaped pigmented area near the center of the retina. The macula’s role is to discern the fine details directly in front of us, like the words on a page or the keys on a keyboard. Eventually, the macula can deteriorate in an eye disease called macular degeneration, introducing a permanent black dot in the center of your vision. Most people with macular degeneration acquire it through old age, but assaulting the eyes with ultraviolet rays can jump-start the disease. In the worst cases, solar viewing can cause permanent blindness, in which the lens of the eye becomes opaque with cataracts. A person with cataracts sees everyday life as if they’re standing behind a fogged window.
// SEVEN
The last solar eclipse to touch South Carolina was the partial eclipse of 1994, which covered 71 percent of the sun for Clemson viewers. But the Aug. 21 “Great American Eclipse” is slated to place Clemson viewers in 100 percent totality for 2 minutes and 37 seconds. The partial phases of the eclipse will begin at 1:07 p.m., with totality starting at 2:37 p.m. During the brief totality, it will be entirely safe for viewers to take off their solar glasses and stare directly at the sun while it is completely covered by the moon. The sun’s corona and chromosphere — its outer and lower atmospheres, respectively — will be visible for this brief period, marking the best time for scientists and enthusiasts to study the sun’s atmosphere. Immediately after totality, viewers must put their glasses back on whenever looking directly at the sun when partial phases resume until the end of the eclipse at 4:02 p.m. Clemson University — given its prime position within three miles of the center of totality — plans to hold a mega-viewing event, complete with plenty of parking, open space, expert demonstrations and vendors.
// EIGHT
During the 5,000-year period from 1999 BCE to 3000 CE, Earth will experience 11,898 eclipses of the sun — of which 3,173 will be total eclipses. Only 4.8 percent of eclipses during this period will be hybrid: the rarest type of solar eclipse, which draws characteristics from annular and total eclipses.
// NINE
One half of the moon’s surface that is facing toward the sun is always illuminated, but as the moon’s orbit brings it around the Earth, we see different portions of that illuminated half, creating the phases of the moon. Solar eclipses can only occur when the moon is in New Moon phase, because that is when its unilluminated side is facing the Earth, thereby casting a shadow on us.
// TEN
In 1961, Clemson’s planetarium was constructed to give visitors a panoramic view of some of outer space’s coolest marvels. Located in Kinard Hall, Room 112, the planetarium can seat up to 38 people for presentations on eclipses, stellar evolution, the Milky Way, our solar system, neighboring galaxies and more.
// ELEVEN
During totality, nighttime is mimicked. As you take off your solar glasses to absorb the amazing view around you, the sky will grow dark, resembling the characteristics of twilight. You might notice the temperature drop by as much as 5 degrees, or the wind change direction or speed. Stars and other planets will become visible in the blackened sky. Even wildlife responds during totality — roosters will crow, grasshoppers will start chirping and some flower blooms will close.
Credits:
PHOTOS: 123RF, WIKIMEDIA COMMONS, CLEMSON UNIVERSITY