Story: Stories from the lives of people in the past

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Changing Concepts of the Universe

about the geocentric view of the Earth about the theories of Nicolaus Copernicus and Galileo Galilei about how Georges Lemaître came up with the Big Bang theory. astronomer, geocentrism, heliocentrism, magnify, microwave radiation, physics Throughout history, people’s understanding of the universe has changed a lot. In ancient times, people believed that the Earth was at the very centre of the universe and that every other object in outer space revolved around it. Disproving this idea was the first step of the journey to discover how the universe came into being. Geocentrism Ancient peoples such as the Greeks and Romans could see five planets in the night sky: Mercury, Venus, Mars, Jupiter and Saturn. They believed that these planets and the sun revolved around the Earth. A few astronomers claimed that the sun was at the centre of the solar system. But for centuries most people believed that the Earth was at the centre of the universe because it seemed as if the sun, the moon and the planets moved across the sky while the Earth stayed still. This view is called geocentrism (the prefix ‘geo’ relates to the Earth). Nicolaus Copernicus (1473–1543) In the 16th century, most people still had a geocentric view of the universe. However, new scientific discoveries began to challenge this view. Polish astronomer and mathematician Nicolaus Copernicus spent his life studying the Earth and the night sky. In 1542, he wrote a book titled On the Revolutions of the Heavenly Spheres. His book suggested that the sun was the centre of the solar system and the planets revolved around it. This view was called heliocentrism (the prefix ‘helio’ relates to the sun). If the Earth was at the centre of the universe, he said, then the five planets should appear in the eastern sky at sunset. However, Venus and Mercury were only ever Nicolaus Copernicus Geocentric illustration of the Universe with the Earth in the centre, from 1660 ©The Educational Company of Ireland seen in the western sky. Copernicus also came up with the idea that the Earth rotated on an axis and this was why the sun appeared to move across the sky.