Discovered the Earth's Roundness: An Examination of the Methods Employed
In the vast expanse of history, the idea of a round Earth has captivated the minds of thinkers for thousands of years. This revolutionary concept, long before being scientifically confirmed, was first proposed by ancient philosophers who relied on philosophical reasoning and simple observations of celestial phenomena.
The Pythagorean school, founded in the 6th–5th century BC, was the first to suggest a spherical Earth. Philolaus, a Pythagorean philosopher who died around 390 BC, proposed a non-geocentric universe with a "central fire" around which Earth and other celestial bodies revolved. Although this model was not heliocentric, it implied Earth was a moving sphere rather than a flat or immobile disc.
Heraclides of Pontus, another ancient thinker from the 4th century BC, proposed that the apparent daily motion of the stars could be explained by Earth's rotation on its axis. This was one of the earliest clear recognitions of Earth's rotation.
By the 5th century BC, thinkers like Pythagoras and Aristotle provided philosophical and observational arguments for Earth's roundness. The shape of Earth's shadow on the Moon during lunar eclipses, and the disappearance of ships hull-first over the horizon, were among the evidence they presented.
These early cosmological ideas arose from philosophical reasoning and simple observations of celestial phenomena. Philolaus’s system, while not heliocentric, introduced the idea of a moving Earth within a cosmic system, influencing later astronomers. The concept of a spherical Earth rotating daily also appeared sporadically in Greek thought but was overshadowed by geocentric models.
Claudius Ptolemy, in the 2nd century AD, rejected the moving Earth and used a geocentric system to explain observations, which dominated for centuries, delaying acceptance of the spherical and moving Earth ideas.
Fast forward to the 6th century BCE, Pythagoras was the first to propose the concept of a spherical Earth. Eratosthenes, the chief librarian at the Library of Alexandria, calculated the circumference of the Earth around 200 years after Pythagoras, using the angle of the sun and the distance between two cities. His calculation, although not as accurate as modern measurements, provided important evidence for the Earth's spherical shape.
In the contemporary era, scientists leverage space-based satellite systems, such as GPS satellites, to make precise measurements and monitor changes in the Earth's surface down to the centimeter level. These advanced tools have confirmed that the Earth is an oblate spheroid, meaning it bulges at the equator and flattens at the poles.
The Earth's roundness is evident through the observation of varying lengths of shadows at different locations. Modern measurements of the Earth's circumference, often facilitated by orbiting spacecraft, contribute to accurate diameter calculations. The Earth's radius is approximately 6,371 km (3,959 mi).
There is still much debate on how Galileo knew the Earth was round, but his observations using the telescope in the 17th century confirmed these concepts scientifically, solidifying the understanding of our spherical home.
From the philosophical musings of ancient Greeks to the precise measurements of modern scientists, the idea of a round Earth has been a fascinating journey through time and thought. The science of geodesy, the measurement and monitoring of the Earth's size and shape, is based on the oblate spheroid shape of the Earth. Despite the ancient origins of this knowledge, it took a long time for everyone to accept the fact that our world is round.
In the realm of education and self-development, the ancient Pythagorean school contributed significantly to the understanding of the Earth's shape, with Philolaus proposing a spherical Earth and a moving cosmic system in the 6th–5th century BC. Modern scientists, on the other hand, employ tools like space-based satellite systems to confirm the Earth's oblate spheroid shape in medical-conditions, such as monitoring changes in the Earth's surface with precise measurements down to the centimeter level. This journey from philosophical musings to scientific confirmation perfectly encapsulates the progress of science and medical-conditions in space-and-astronomy over thousands of years.
