Hipparchus of Rhodes www assignmentpoint com Hipparchus was

• Hipparchus was a Greek astronomer who lived between 190 -120 B. C.

Hipparchus of Rhodes • Became a famous astronomer in Alexandria. • Around 150 BCE

The Table of Chords • Hipparchus invented the table of chords, a list of

Precession of the equinoxes • Hipparchus also calculated that there is a very slow

The Problem of the Planets, again • 300 years after Hipparchus, another astronomer uses

The Eudoxus-Aristotle system for the Planets • In the system of Eudoxus, extended by

The Eudoxus-Aristotle system for the Planets, 2 • The motions of the visible planet

• The Greek astronomer and mathematician Hipparchus produced the first known table of

Slides: 9

Download presentation

Hipparchus of Rhodes www. assignmentpoint. com

• Hipparchus was a Greek astronomer who lived between 190 -120 B. C. He is considered the father of trigonometry, a branch of mathematics which studies the angles of sides of triangles. Hipparchus also developed the first accurate star map. www. assignmentpoint. com

Hipparchus of Rhodes • Became a famous astronomer in Alexandria. • Around 150 BCE developed a new tool for measuring relative distances of the stars from each other by the visual angle between them.

The Table of Chords • Hipparchus invented the table of chords, a list of the ratio of the size of the chord of a circle to its radius associated with the angle from the centre of the circle that spans the chord. • The equivalent of the sine function in trigonometry.

Precession of the equinoxes • Hipparchus also calculated that there is a very slow shift in the heavens that makes the solar year not quite match the siderial (“star”) year. – This is called precession of the equinoxes. He noted that the equinoxes come slightly earlier every year. – The entire cycle takes about 26, 000 years to complete. • Hipparchus was able to discover this shift and to calculate its duration accurately, but the ancients had no understanding what might be its cause. www. assignmentpoint. com

The Problem of the Planets, again • 300 years after Hipparchus, another astronomer uses his calculating devices to create a complete system of the heavens, accounting for the weird motions of the planets. • Finally a system of geometric motions is devised to account for the positions of the planets in the sky mathematically. www. assignmentpoint. com

The Eudoxus-Aristotle system for the Planets • In the system of Eudoxus, extended by Aristotle, the planets were the visible dots embedded on nested rotating spherical shells, centered on the Earth.

The Eudoxus-Aristotle system for the Planets, 2 • The motions of the visible planet were the result of combinations of circular motions of the spherical shells. – For Eudoxus, these may have just been geometric, i. e. abstract, paths. – For Aristotle the spherical shells were real physical objects, made of the fifth element.

• The Greek astronomer and mathematician Hipparchus produced the first known table of chords in 140 BC. His work was further developed by astronomers Menelaus (ca. AD 100) and Ptolemy (ca. AD 100), who relied on Babylonian observations and traditions.