Throughout history philosophers and scientists have been debating about the shape of the Earth. The interest to the universe began in antiquity and increased during the Enlightenment period. In ancient days, philosophers proposed various theories about the shape of the Earth that were rather mysterious than realistic. However, each theory was a step forward in discovering the universe. Furthermore, it is important to summarize the initial thoughts of the shape of the Earth and supporting phenomena that guided people to wonder about the spherical shape in ancient days. For better understanding of the history, it is necessary to mention studies and experiments in the 15th through 18th century, as well as the first incorporation of the gravity in shaping the Earth.
The first ideas about the shape of the Earth
The initial thoughts about the shape of the Earth were different from what it believes today. Many ancients’ cultures believed that the Earth is flat, including Anaximander of Miletus, a Greek philosopher. He was the first to develop a field of study called Cosmology, which can be explained as systematic philosophical view of the world. Anaximander believed that the shape of the Earth is similar to the shape of a drum. According to him, the earth has a cylindrical shape, round and curved. The surface of the Earth is flat and stays in equilibrium at the center of the cosmos.
The idea of flat Earth was initial to many scientists of Hellenic world. A Greek mathematician Pythagoras believed that the Earth was the sphere that moved around the fire (is not a sun), like other spheres. He mentioned that there were 10 objects, including the Earth, circling the central fire. Pythagoras’ ideas were the first coherent system, where celestial bodies move in circles. This idea was relevant for two thousand years. Pythagoras made a significant contribution in development a sophisticated cosmology.
Most of the people in ancient time believed that the Earth is flat. However, Aristotle was not agreed with them. In 4th century B.C., he observed that when the Earth came between the moon and the Sun, a lunar eclipse occurred. Also, Aristotle observed that the shape of the Earth’s shadow was round. He insisted that the shape of the Earth cannot be flat, since the shadow is round. In addition, Aristotle considered the position of the North Star. He observed that as long as you go farther to the North, the closer to the middle of the sky the North Star move. Furthermore, he observed the ships sailing into ports. Aristotle noticed that he is able to see the top of the ship before he could see the rest of the ship. Aristotle conclusions were the step forward to prove that the Earth is round.
Supporting phenomena guided ancient people to wonder about spherical shape
For over thousand years, scientists believed that the Earth is round. Different justifications were proposed to prove that that the idea of Earth’s roundness is accurate. It was mentioned that people can observe various stars from different places of the Earth. Also, on the same day of the year, the position of the Sun varies between different places. In addition, sailors observed that the coastline gradually rise above the horizon when approaching them by sea. That was the supporting phenomena that guided ancient people to wonder about spherical shape of the Earth.
Studies and experiments in the 15th through 18th century
Furthermore, in the 15th through 18th century there were done numerous studies and experiments to prove the observations of ancient people. A French scientist Jean Fernel, was first devoted to astronomical and mathematical studies. In 1528, in his work Cosmotheoria he recorded a determination of a degree of the meridian by measuring the number of revolution of a wagon wheel, when he was traveling from Paris to Amiens. In addition, he calculated the height of Sun at midday and then he travelled to the North to observe what this height will be 1o north. Fernel’s experiment and calculations became a practical facts that helped to support the idea of Earth roundness.
In 1669, a French astronomer Jean-Félix Picard introduced the telescope to observe angles of triangulation and star altitudes. He was the first person who most accurately measured the size of the Earth. He was measuring two baselines of 7,605& 11,038 meters on his triangulation from Malvoisine to Sourdon, by using wooden rods. He calculated that 111.210 km was equivalent to 1o. Furthermore, he computed the Earth radius based on the distance corresponding to 1o. Jean Picard is considered to be the founder of astrometry in Paris, due to his work with quadrant and geodesic measurements using a sector.
The incorporation of the gravity in shaping the Earth
Gravity is the force by which a planet or other body draws objects toward its center. The force of gravity keeps all of the planets in orbit around the sun. Earth’s gravity keeps all creatures and objects on the ground; as well it is what makes anything to fall. The first modern work on gravitation began with experiments of Galileo Gaalilei between 16th and 17th centuries. Dropping balls from the Tower of Pisa is his most famous experiment. Galileo demonstrated that different size balls fall at the same time. In another words, gravitational acceleration is the same for all objects. Galileo’s experiment was the foundation for the development of Newton’s theory of gravitation.
In 1687, Sir Isaac Newton, an English physicist, proposed the law of universal gravitation that was published in Principia. According to this law, various particles of the universe are attracted by other particles with the help of a force, that proportional to the product of the two masses and inversely proportional to the square of the distance between them. Newton’s theory was useful for prediction of the existence of Neptune that was based on motions of Uranus. Newton’s theory was a significant for the development of Geodesy and is still used for the modern gravitational calculations.
The early philosophers strongly believed that the shape of the Earth is flat. However, some of them still were questioning this theory. Scientists were observing stars and Sun, measuring the distance and calculating the angles. Numerous observations proved that the Earth is certainly not a flat in its shape, but rather spherical. Later, scientists conducted the experiments that scientifically supported theory about the roundness of the Earth. Galileo and Newton showed that besides the shape of the Earth, there are other important facts of our universe, such as gravity. Certainly, there are still more discoveries about our Earth to be done.