ASTRONOMERS IN HISTORY

ARISTOTLE

• Aristotle was a student of Plato and has influenced fields of study including Science, Theology, Philosophy etc.
• He taught that the Planets and Stars were on concentric spheres centered on the Earth.
• Aristotle dominated scientific thinking for many years. His views on motion were widely accepted because they seemed to support what people observed in nature. For example, Aristotle thought that weight affected falling objects.
• His works contain the earliest known formal study of logic, which was incorporated in the late nineteenth century into modern formal logic.
• Aristotle believed that since all things fall toward the center of the Earth or move round the Earth, that the Earth must be the center of the Universe. The Moon and planets move around the Earth in circular orbits but must move in circles within circles to explain the variance observed in their orbits.
• Aristotle's views on physical science shaped medieval scholarship. but made significant contributions to the way we study the universe today

ARISTARCHUS

• Aristarchus was a Greek astronomer who believed that Earth rotates on its axis and revolves around the Sun.
• Aristarchus is best known for two things, his belief that the Earth revolves around the Sun and his work attempting to determine the sizes and distances of the sun and moon. Although he wrote many volumes
• measure the relative distances from the Earth of the Sun and the Moon .
• Aristarchus also figured out how to measure the size of the Moon.

PTOLEMY

• Ptolemy believed that the Earth was the center of the Universe.
• (geocentric theory)
• Even starting with this incorrect theory, he was able to combine what he saw of the stars' movements with mathematics
• His famous work was called the Almagesti
• In order to make his predictions true, he worked out that the planets must move in epicycles, smaller circles, and the Earth itself moved along an equant. None of this was true, but it made the math work for his predictions.

COPERNICUS

• Nicolaus Copernicus came up with a radical way of looking at the Universe. His heliocentric system put the Sun (helio) at the center of our system.
• He used his own observations of the movements of the planets to back up his idea.
• His ideas, including the revealation that the Earth rotates on its axis, were too different for most of the scholars of his time to accept. They used only parts of his theory. Those who did study his work intact often did so in secret. They were called Copernicans.

KEPLER

• Kepler was a German mathematician, astronomer, and astrologer. A key figure in the 17th century scientific revolution, who is best known for his laws of planetary motion,
• His descriptions of planetary motions became known as Kepler’s laws.

GALILEO

• had his own ideas on how motion really worked, he devised a telescope that could enlarge objects up to 20 times. He was able to use the telescope to prove the truth of the Copernican system of heliocentrism
• Other scientists, including Sir Isaac Newton and Johannes Kepler, seized the telescopes importance and were able to learn even more about the ways of the world and the heavens beyond.

GEOCENTRIC MODEL

• the Geocentric Model (also known as geocentrism, or the Ptolemaic system) is a description of the cosmos where Earth is at the orbital center of all celestial bodies.

HELIOCENTRIC MODEL

• The heliocentric model is a theory that places the Sun as the center of the universe, and the planets orbiting around it.