H-Astronomy-001.htm

Astronomy 2000BC to 1400

Stonehenge III in England, an astronomical shrine of early people

All humans from any place and time have shown an intense interest if the heavens. It was alive, ever changing, under the control of some powerful beyond man’s grasp. Countless concepts and meanings were created to explain.

The Stonehenge I, first built in 2000BC, was an instrument designed to make sense of this predictable, yet unpredictable phenomenon that so effected their lives. Prof. Fred Hoyle, University of Cambridge, wrote an excellent booklet “Stonehenge – An Eclipse Predictor”. Hoyle tells of there being three versions where Stonehenge I was the most sophisticated as a means to track seasons plus forecast eclipses. It would have required hundreds of years to evolve and maintain the method. The original concept was lost after the bronze age and peoples hauled large stones over a long distance with great difficulty by land and sea from Wales. These shown above were an attempt to recapture the meaning which had been lost.

Double click on this Stonehenge to call up the booklet, allowing yourself time to read its interesting content.

The night sky has looked much the same for the last 10,000 year – the ancients saw what you see

Astrologers Zodiac map of sky scenes (signs)

The ancients were fascinated by the fact during the passage of a year, the scene of stars in the sky shifted as if resetting the stage for a play. The ancients gave the scenes names and Astrologist passed them down. Some placed much significance in the Zodiac, the map of scenes (they called signs). The “sign” in place when they were born – was believed to influenced their lives. Fortune Tellers have long practiced the art of using the Astrologers Zodiac in conjunction with palm reading. Astrology was taken seriously, even by Brahe & Kepler while defining planetary behavior.

From prehistoric time man has believed their lives were controlled or influenced by the stars. Early priests were astronomers. Sumerians and Babylonians focused on documenting what they saw, making star catalogs over hundreds of years. The Chinese also recorded events as novas, very bright but brief stars. As soon as ancients could write records they were also creating calendars.

Under Hammurabi of Babylon a Star Catalog was created about 1600 BC and maintained, these records were written on clay tablets. The Babylonians made excellent observations but made no attempt to explain them. Their clay tablet records were later stored in a fabulous library in Alexander Egypt. This library was later destroyed by early rampaging Christians.

The Babylonians built large temple towers in which the astronomer-priests lived at the top. They managed to convince the people that to gain favor with the gods and assure good crops, a young woman’s first child was to be conceived by the Gods. They were to present themselves to the gods, exposed to the sky at the top of the towers. In due time a “God” would come out and make them pregnant. Con-artistry is an ancient art.

The early Egyptians and Greeks did not contribute much to actual astronomy, they gave names to Gods they believed were in control.

The Greeks were the first to apply mathematics and logic to what they saw. Pythagoras (pre Plato) and Plato 400 BC mathematicians and philosophers followed by Platos students Eudoxus (Euclidian geometry) and Aristotle were the first to apply geometry to astronomy. Eudoxus was the first to construct a system of 27 spheres centered on the Earth to imitate planetary motion. Aristotle added 28 more spheres to better reflect observed motions. Aristotle model was based on the earth being a sphere at the center and that all bodies were made of four basic elements: earth, air, fire & water. Wandering stars, actually planets, made modeling motions very difficult.

The mystery of the Wanders retrograde motion was not solved until after Columbus by Kepler

Greeks Apply Geometry to Astronomy

Ancients knew the moons phases and the relationship of earth & sun, most believing the sun was further away than the moon

The Greeks

Whereas the Babylonians gathered information the Greeks applied their advances in geometry and mathematics to model the Cosmos. The work of these people were inner woven as teacher, student, friend, each building on the other. They all believed the earth was round and that the stars were part of a sphere about the earth. They struggled to using small circles in the blanket of stars to account for movements of the wanderers – never feeling they had solved the problem.

Pythagorus (582-500BC} made an earth centered “Music of the Spheres” model – developed Pythagorean theorem

Plato (428-348BC ) Influence Greek model of Cosmos

Eudoxus (400-347BC) Friend of Plato, synthesized Greek, Egyptian & Babylonian data to make a mechanical model with earth at center plus eccentrics to account for wanderers. Contributed to Euclidian Geometry

Aristotle (384-322BC) Aristotle’s model with earth is round, because ship sails go out of sight, at the center of a rotating sphere of stars at equal distance

Aristarchus (310-330BC) Calculated the relative distance to the moon and sun.

Euclid (__300BC__) Compiled book called “Elements”, and used as a master text for centuries.

Eratosthemes (276-194BC) In 200BC calculated the circumference of the Earth.

Ptolemy (127-151) would later compile what was known into what was later transcribed by the Arabs as the Almagust (great works) which was followed until Copernicus.

Aristotle believed the Earth was a sphere as this explained how a ship at sea disappeared and from travelers reports of observing the polar star, the center of rotating stars.

Aristotle system at left, he rejected heliocentric (sun centered) system due to parallax.

Ptolemy AD 125 made use of the Alexandria Egypt library, which included the Babylonian records, to write The Mathematical Composition of Claudius Ptolemy, in Greek. Though Christians later destroyed the library, Ptolemy’s composition survived. Conquering Moslems transcribed the work into Arabic calling it Almagest, meaning Great Works, by which it was known and followed by astronomers until the 1400’s. The sun centered system of Aristarchus was abandon until Copernicus.