PTOLEMY

PTOLEMY 

-Born 90 AD and died 168 AD

-Astronomer, Mathematician, Geo


-claimed to have derived his geometrical models from selected astronomical observations by his predecessors spanning more than 800 years (though astronomers have for centuries suspected that his models' parameters were adopted independently of observations)

-created the aAmagest which contains a star catalog and lists forty-eight constellation

HIPPARCHUS

HIPPARCHUS

 - Born 190 BC in Nicaea and died 120 BC

- Astronomer, Mathematician.

- Possibly one of the first to discover a method in predicting Solar Eclipses using his solar and lunar theories and his trigonometry skills.

-Discovery of the earths precision.
 
-The computation of the first comprehensive star catalog of the western world

-Possibly invented the astrolabe and the armillary sphere, which he used during the creatin of the star catalog.  

-Hipparchus is thought to be the first to calculate a heliocentric system, but was proved wrong because the calculations showed the orbits were not perfectly circular as believed to be mandatory by the theology of the time and soon gave up the theory.

ARISTOTLE

ARISTOTLE 

- Born in Stagira 348 BC and died in 322 BC
- Teacher, Writer, Philosopher.
-Thought that celestial bodies were a sphere and attempted to convince people of his time that his theory was true.
-A method that he used to prove this is observing that during a lunar eclipse, the shadow of the earth is always circular.
-Found that mars is higher up in "heaven" than the moon by seeing the moon pass in front of mars.
-Discovered the physics that which explained change, motion, void and time which made it easier for scientists to study speed and movement of gravity, stars, etc.

-Postulated a fifth element called aether which is believed to be the main content of celestial bodies.

ERATOSTHENES

ERATOSTHENES

-Born in 276 BC in Cyrene and died 194 BC in Capital of Ptolemaic Egypt.

-Poet, Librarian, Scholar, Inventor.

-First person to calculate the circumference of the earth by measuring the altitude of the noontime sun, the difference in the zenith angle and geometry.

-First person to prove that the earth was round.

-Possibly calculated the accurate distance from the sun to earth

-Created Leap Day

- Has a period on the lunar geologic timescale, a crater on the moon, and a sea mount in the Mediterranean
 sea, all named after him.

PYTHAGORAS

PYTHAGORAS

-Born about 569 BC in Samos, Ionia, Greece.

-Mathematician and Astronomist

-Thought that everything related back to math and that everything could be

  predicted through it and was measured in rythmic patterns or circles.

-One of the first to say that the Earth was round (along with Galileo), a theory that was

  later proved by Aristotle.

-Believed that the earth was a perfect sphere and that it was the centre of universe.

-Discovered that the morning star and the evening star were both the same object,

  the planet Venus.

-Pythagoras' followers called themselves Pythagoreans.