Early Astronomy v Ancient Greeks Seven planetai Sun
- Slides: 10
Early Astronomy v Ancient Greeks • Seven “planetai” • Sun, Moon, Mercury, Venus, Saturn, Jupiter, Mars • 7 days of the week? • GEOCENTRIC SOLAR SYSTEM Aristotle
Ptolemy: u u 500 years after Aristotle Claudius Ptolemy Also a Greek! Supported Geocentric System Noticed some planets appear to move backwards (Retrograde Motion)
The universe according to Ptolemy, 2 nd Century A. D.
Nicolaus Copernicus v Heliocentric (Sun-Centered) Solar System • Earth was a planet (like the others)! • Planets orbit Sun counterclockwise • Closer planets orbit faster • Very unpopular idea (why? )
Johannes Kepler u Laws of Planetary Motion • Law of Ellipses – planets orbit in elliptical paths (not perfect circles) • Law of Periods (a planet’s “year” is proportional to its distance from the Sun) p 2 = d 3
Using Kepler’s Third law p 2 = d 3 If an object is 4 AU from the Sun, how many years does it take to orbit the Sun? 1 Astronomical Unit = 149 598 000 km (1 AU= distance from Earth to Sun) Example • 4 AU from Sun p 2= (4)3 p 2=64 p= 64 = 8 yrs
Kepler’s 3 rd Law
Galileo Galilei u Constructed 1 st “astronomical” telescope Found: • • Four large moons of Jupiter Phases of Venus Features on the Moon Sunspots
Isaac Newton Why do planets move in ellipses? ? ? u Law of Inertia: an object moves in a straight line unless acted upon by an outside force! u Law of Universal Gravitation u Force of gravity + inertia results in the elliptical orbits discovered by Kepler
Planetai
Ancient greeks
Ancient greek values
Learning astronomy by doing astronomy
Learning astronomy by doing astronomy activity 1 answers
Learning astronomy by doing astronomy activity 1 answers
Astronomy in ancient rome
Which era is known for symmetrical tree like designs
Option greeks wikipedia
Why did tyrants fall out of favor with the greeks?
Above all else i must be saved
