180 likes | 280 Views
Today! From Earth’s Perspective: Lunar Motion A Brief History of Astronomy. FROM NOTES: Lunar motion : tidally locked - -gravity makes same side (with a displaced core) always face earth. Synodic period - -29.5 days --cycle of phases.
E N D
Today! From Earth’s Perspective: Lunar Motion A Brief History of Astronomy
FROM NOTES: Lunar motion: tidally locked--gravity makes same side (with a displaced core) always face earth. Synodic period--29.5 days --cycle of phases. --Length of day on the moon. --Lunar phases--see diagrams. Siderial period--27.3 days --with respect to stars.
The Moon was hit by a large object, making oval-shaped, and front side is closer to iron core than back. This keeps it tidally locked with same side facing Earth.
A Brief Early History of Astronomy: (From NOTES) 5,000 BC--Sumerians--astrology and '12th planet'? 2,500 (or 8,500) BC--sphinx and great pyramid. 1,600 BC--Babylonians--star and planet tables. 1,500 BC (or much earlier)—Hindus --cycles of cosmos and lifetime of sun. 500 BC--Pythagoras--earth and heavens spherical. 350 BC--Aristotle--physics of forces, geocentric universe. 250 BC--Aristarchus--first sun-centered system. 200 BC--Erastosthenes--accurate size of earth. 130 BC--Hipparchus--epicycle, precession, charts. 7 AD?--Wise men tracked the Christmas star --Saturn conjunct Jupiter? 125 AD--Claudius Ptolemy--accurate geocentric model. 400 AD Hypatia and the Fall of the Alexandrian Library
5,000 BC--Sumerians– wrote of astrology and '12th planet‘ with godlike inhabitants? Nibiru? Zecharia Sitchin His book.
2,500 (or 8,500?) BC--Sphinx and Great Pyramid. Harvard research found water markings on Sphinx, dating it to prior to 8500 BC
1,600 BC--Babylonians--star and planet tables. The Babylonian zodiac was sidereal, i.e. longitudes were not measured from the vernal equinox (the intersection with the celestial equator), but from a small number of bright fixed stars near the ecliptic. The most important reference stars appear to have been Aldebaran (defining 15º Taurus), Pollux (0º Cancer), Regulus (5º Leo), Spica (0º Libra), Antares (15º Scorpius) and Deneb Algedi (0º Aquarius).
1,500 BC (or much earlier)—Hindus --cycles of cosmos and lifetime of sun.
500 BC--Pythagoras—the earth and heavens are spherical. Hence the ‘music of the spheres’, he called it.
350 BC--Aristotle--physics of forces, geocentric, or Earth-centered universe. Planets on spheres. Each one has several, some going backward to account for retrograde motion.
200 BC--Erastosthenes--accurate size of earth determined by the angle of Sun’s rays at noon.
130 BC--Hipparchus—epicycle designed for retrograde motion, precession of equinoxes discovered, charts of planet motion. Mr. Observer!
7 AD?--Wise men tracked the Christmas star --was it Saturn conjunct Jupiter? Painting by Giotto: Christmas star as Halley’s comet?
125 AD--Claudius Ptolemy--accurate geocentric model of universe Epicycle upon epicycle—its defects were it’s complexity and different handling of inner planets from outer.
400 AD Hypatia and the Fall of the Alexandrian Library Poor girl. She was head of the Alexandrian Library, and Christian fanatics cut off her limbs and head, and dragged her dead body behind her chariot through the streets of Alexandria. After all, she didn’t believe the Earth was the center of the Universe! Then they burned down the Library, destroying about ½ the knowledge of the ancient world.