Thanks to the convenience of the internet and social media, the August 21 “Great American Eclipse” will allow unprecedented numbers of people from around the world to participate, even if they are outside the path of totality. This global access makes it one of the more notable eclipses on record, joining a group of others that have stood out due to their scientific or cultural significance.
For instance, more than 2,100 years ago, the Greek astronomer Hipparchus compared observations of such an eclipse made from different spots on Earth to calculate the distance between the Moon and Earth. His estimate of 268,000 miles is within about 11 percent of the actual distance, which is not bad considering the archaic observing techniques of the time.
The first scientifically accurate pictures of a total solar eclipse were captured during a July 28, 1851 event, which was visible from Scandinavia, Russia, and North America. Twelve years prior, French artist/print maker Lois-Jacques-Mandé Daguerre had invented the first commercially successful photographic process, which created an image on a highly polished, silver-plated sheet of copper sensitized with iodine vapors; the finished product was known as a daguerreotype. For the 1851 eclipse, several observers—particularly Julius Berkwoski at the Royal Observatory in Königsberg, Prussia (now Kaliningrad, Russia)—incorporated Daguerre’s technique to capture images of the darkened Sun.
In 1868, British astronomer Norman Lockyer and French astronomer Pierre Jules César Janssen independently discovered helium, the second most abundant element in the universe, while observing a total solar eclipse. Helium’s name derives from the circumstances of its discovery—the word helium comes from Helios, the Greek god of the Sun. Twenty-seven years would pass until scientists found helium on Earth.
The 2017 total solar eclipse will stretch across the United States, from the Pacific to Atlantic oceans. The last time this occurred was on June 8, 1918. Like the 2017 version, it saw Lowell Observatory astronomers and other staff members leave Arizona in order to witness the event. The Lowell observers traveled to Kansas and used a variety of instruments for this work, including two lenses – each with a diameter of five inches and focal length of 38.7 feet —borrowed from the U.S. Naval Observatory (USNO). These were two of the so-called “Transit of Venus objectives,” used to observe the transits of 1874 and 1882. The USNO also organized an observing expedition, sending a team of observers to Baker City, Oregon. One of the team members was artist/physicist Howard Russell Butler, who watched the 112-second period of totality and then painted a legendary color depiction of what he saw.
More famously, in 1919 British astronomer Arthur Eddington traveled to an island in the Pacific Ocean to photograph stars around an eclipsed Sun. Albert Einstein had predicted in his general theory of relativity that starlight would not travel in a straight line but instead bend slightly as it passed by an object, whose gravity would tug on the starlight. Eddington saw a perfect opportunity to test this prediction by observing and measuring starlight as it passed by the darkened Sun during a total eclipse. Eddington’s findings seemed to support Einstein’s prediction (later astronomers have debated the accuracy of Eddington’s measurements) and made Einstein an instant global celebrity.
Comparable in status to these real-life eclipses is a fictional version conjured by the inimitable Mark Twain. The hero of his 1889 novel A Connecticut Yankee in King Arthur’s Court (originally titled, simply, A Yankee in King Arthur’s Court) is Hank Morgan, a munitions factory manager who achieves a place of status in sixth century England when he correctly predicts a total solar eclipse.
These solar eclipses of 1851, 1868, 1918, and 1919, as well as the Hipparchus and Twain versions, are some of the more celebrated eclipses on record. While solar eclipses in general tend to overshadow their lunar cousins, particularly in the scientific knowledge they reveal, lunar eclipses still have their own historical heritage and are worth including here, if but a single, well-known example.
Half a millennium ago, explorer Christopher Columbus used his knowledge of an upcoming total lunar eclipse to settle a dispute with native Jamaicans. On Columbus’s fourth voyage to the New World, in 1504, he and his crew were stranded on Jamaica for more than a year. A feud between the crew and natives developed, and Columbus knew he had to settle it before lives were lost. Probably by checking an almanac, Columbus knew that a total lunar eclipse would occur on March 1. That night, he gathered the natives and told them that the “Almighty” was going to take away their Moon because of the natives’ poor relations with the sailors. Later, as the Moon was eclipsed, the natives apparently were horrified and begged for forgiveness, promising to be friendly if only the moon was “returned.” The Moon eventually did come back and peace was restored.
Kevin Schindler is the Lowell Observatory historian