This article explores how humanity has developed and debated the shape of the Earth, from ancient to modern times, from theories that it is round to claims that it is flat. It also covers the historical process of how scientific truths have been confirmed and accepted over time.
The story begins when I was about twelve years old. I was watching Star Wars with my father. When the movie came to the scene where Luke Skywalker blows up a star, he told me that the earth was flat, not round. I laughed and said. “Dad, that’s ridiculous, everyone knows the earth is round!” My father said with a twinkle in his eye. “Son, you shouldn’t blindly believe in things you can’t prove. Why do you think the earth is round?” It was obvious to me that the earth was round. I had seen many photographs of the earth, and in them it was round! But my father countered that the photographs could have been manipulated.
Of course, he didn’t actually believe the Earth was flat. Maybe he was trying to get me to think about things I hadn’t thought about before, maybe he was just annoyed with me, but I couldn’t find any other evidence that the Earth was round other than the photographs, which prompted me to look into how the idea of the Earth being round developed. In this blog post, we’ll look at how the theory of the Earth being round developed. Specifically, I’ll look at the theories of ancient Greek scholars, starting in 800 BC, who believed the Earth was round. I will then explain how the theory of a round Earth was proven in several ways throughout the Late Antiquity and the Middle Ages. Finally, I will demonstrate that absurd theories cannot adequately describe natural phenomena by showing that even in the 19th century there were people who believed the Earth was flat.
Until about 500 B.C., people believed that the earth was flat and that if you went to the edge of the earth, you would find a cliff. They thought that the reason the sun was invisible in the west was because it fell below the cliff. Homer, an ancient Greek author, wrote The Iliad in 800 BC, and the perception that the Earth was flat was popularized. Consistent with the prevailing wisdom of his time, he believed that the earth was flat as a shield and that Okeanos, the god of the sea, covered it with water. This belief was not just expressed in literature: Herodotus, famous for his histories, repeatedly used the phrase “angular part of the earth” in his writings around 450 BC. Thales, the father of philosophy, also believed the earth was flat based on his voyages in the Mediterranean. Of course, the West was not alone in believing that the earth was flat. Chinese astronomical texts from the Zhou Dynasty recorded the “Tianyuan Fatalism” theory, which states that the earth is flat and the sky is circular. The theory was thought to explain the yin and yang of the heavens, and it remained the authoritative theory of the shape of the Earth in East Asian societies until the end of the pre-modern era.
As civilization developed, however, people moved beyond mere speculation and continued to observe and explore the Earth. Understanding the Earth was seen as a prerequisite for farming and trade. They studied and argued about the workings of nature, and slowly began to piece together the facts. Around 400 BC, the philosopher Socrates noticed that when a ship approaches a shoreline, the sails appear before the ship’s hull, explaining that this is because the surface of the ocean is gently curved, like the surface of a sphere. Aristotle, too, argued that the Earth “must be spherical” for philosophical reasons. He also provided empirical evidence. When he observed lunar eclipses, where the Earth’s shadow obscures the moon, the shadow always looks like part of a giant circle. He argued that this meant the Earth was round. With famous scientists supporting the hypothesis that the Earth is round, Roman astronomical theories came to embrace the idea of a spherical Earth. From Europe, the idea of a spherical Earth spread throughout the world. In late antiquity (200-800 CE), the Indian astronomer Aryabhata accepted the idea of a spherical Earth, calculating the Earth’s equatorial circumference and recording it in his writings. By the early Middle Ages, Islamic scientists were using sphericity to determine the direction and distance to Mecca from any point on Earth.
As common knowledge spread among astronomers, it is thought that astronomers and sailors knew that the Earth was spherical at least by the 12th century. However, even at this time, the idea that the Earth is round was not widely accepted. This is because geoscience was not considered a liberal arts subject, so there were fewer opportunities for the public to learn about it. This was true for commoners who were busy earning a living, as well as for nobles who had access to education. In addition, books were published that propagated misconceptions. For example, in 12th-century France, books were published that claimed the Earth was a flat disk. Of course, these books were written in vague terms, but they took evidence from myths and epics and seemed logical. So one question arises. Will time settle this issue? Would modern people still believe that the Earth was flat?
Fortunately, over time, the fact that the Earth is spherical has become common knowledge to people around the world. The event that drove a wedge into this belief was Ferdinand Magellan’s circumnavigation of the world in 1519. If the Earth were flat, the ship would only go in one direction and would never reach its original position. As if to prove what many navigators and scientists thought, after three years of traveling through the Pacific and Atlantic oceans, the ship returned to Spain. Since no theory of a flat Earth could explain the ability to circle the globe, it was impossible to refute Magellan’s realistic proof. Later, as civilization advanced, education became more widely available to the masses, and the efforts of many scientists led to a global acceptance of the obvious fact that the Earth is round.
Surprisingly, however, some people still believed that the Earth was flat well into the 20th century. It takes an unusual person to claim that the Earth, long thought to be spherical, is flat again. Samuel Robotham was just such a person. A religious fundamentalist, he cited a passage in the Bible where angels stand at the four corners of the earth. If the earth was round, he reasoned, then the corners could not exist, and he declared that the concept of a round earth was “directly contrary to the word of God.” In an attempt to overcome the ignorance and foolishness of the masses who believed in a round earth, Robotham presented what he believed to be irrefutable scientific evidence, at least in his opinion. He argued that astronomy was a hoax based on false premises, and therefore any evidence that appeared to support the spherical theory was an illusion. For example, he announced that the rising and setting of the sun is simply a visual illusion. He later attempted an experiment to show that the waterways were flat in an attempt to expose astronomers’ despicable fraud, but it was refuted. After Robotham’s death, his arguments were carried on, and the fight for simple truth continued. Since Aristotle, the lone voice in this debate has been a lonely one.
It took countless people and their efforts to establish the facts we know as scientific truths. Take the fact that the Earth is round. Before we could see it from space, humans had to make inferences about the Earth’s shape without being able to observe it directly. While the history of science usually focuses on explaining what we see with our eyes, the explanation of the shape of the Earth is different from other scientific discoveries in that it starts with an inference without observation: the Earth is round (or flat), and natural phenomena are explained based on the premise that it is. This means that unproven stories became widespread because they were irrefutable. To combat the spread of false theories, scientists came up with other theories, each of which depended for its survival on whether it could support newly discovered natural phenomena. Theories ranged from Thales, who claimed the Earth was flat, to Ferdinand Magellan, who proved the Earth’s shape by circumnavigating the globe. Over the course of 1500 years, the debate was both ruled out and validated by newly discovered natural phenomena. And even when a theory claimed that all existing natural phenomena were false, such as Samuel Robotham’s flat earth theory, the absurd theories did not adequately explain natural phenomena. The history of the spread of spherical Earth theories shows that currently accepted theories are widely used because they can explain all scientific phenomena. It also illustrates that even theories that seem to be true can be refuted whenever new phenomena are discovered.
