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.
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.
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.
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.
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.