For centuries, humans have been fascinated by the rare celestial event of a total solar eclipse. Ancient civilizations were known to worship the sun, and these natural phenomena were interpreted as omens that brought either good or bad fortune. However, it wasn’t until relatively recently that we began to understand the science behind eclipses and develop reliable methods for predicting them. Even now, with modern technology and sophisticated mathematical models, predicting eclipses can be a difficult and challenging task. In this article, we will explore the fascinating history of eclipse prediction, and the ongoing efforts to improve our understanding of this awe-inspiring event.
The town of Exmouth in Western Australia is set to witness a total solar eclipse on April 20, 2023. While eclipses have fascinated humans for millennia, they can be difficult to predict. The Sun and Moon were the most captivating celestial bodies to ancient cultures, and they tried to anticipate and predict their movements. While the Sun’s movement is quite simple, the Moon’s movement across the sky is much more complex, with phases and variable apparent sizes. On top of this, the Moon appears to rock and wobble haphazardly, making it hard to accurately describe its orbit.
During a lunar eclipse, where the Earth blocks sunlight that would otherwise illuminate a full moon, the dimmed Moon takes on a bloody hue. Ancient cultures noted their occurrence in writing and art and discovered the repeating characteristics of these events. Various cultures discovered that eclipses occurred on an 18-year cycle. It was mentioned in written records by the Babylonians and Assyrians and used for ceremonial purposes by Torres Strait Islanders. This 18-year cycle is known as a Saros cycle, representing how long it takes for the Sun-Earth-Moon system to return to almost exactly the same triangular configuration. If you observe a lunar eclipse, you can expect another one visible from most places on Earth 18 years later.
While ancient cultures may have been able to predict lunar and partial solar eclipses, there is no convincing evidence of people predicting the times and locations of total solar eclipses. The Antikythera Mechanism, an astoundingly complicated 2,000-year-old mechanical device used to predict the night sky, could likely calculate the 18-year Saros accurately. Today, NASA uses a highly advanced form of an ancient technique – pattern recognition – to predict both solar and lunar eclipses for 1,000 years into the future.
The first successful prediction of a total solar eclipse in both time and location occurred in 1715. Edmond Halley, known for his discovery of Halley’s Comet, predicted to within four minutes and 20 miles, a total solar eclipse that passed over his house in London. He made full use of Isaac Newton’s new theories of gravity and orbital mechanics. Witnessing a total solar eclipse is a shared experience that has driven advancements in mathematics and orbital mechanics. With its beauty we have been forced to embrace the limits of our scientific knowledge.
