26-10-12 The universe (2) :

Julius Caesar 45 b.c

· Julian Calendar

Copernicus 1543

· He published de Revolutionibus Rrbium Coelestium

· Helicocentric Universe.

· He proposed the idea of rotating earth that revolved around the Sun

· He died before his ideas were spread.

Gregorian calendar, October 1582

· It includes leap years with 366 days

· This is the calendar some people use in the Western world

Tycho Brahe

· DATA, DATA, DATA

· He was an eccentric mathematician who worked for the church

· He complied volumes and volumes of very accurate data of position on hundreds of celestial bodies

Johannes Kepler

· Was Brahe’s main assistant when Brahe died

· He used Brahe’s data to create the 3 laws of planetary motion

· He was the first strong supporter of Copernicus

Laws: 

-1. The orbit of a planet/comet about the Sun is an ellipse with the Sun's center of mass at one focus.
-2. A line joining a planet/comet and the Sun sweeps out equal areas in equal intervals of time.
-3. The squares of the periods of the planets are proportional to the cubes of their simimajor axes.

                

Galileo Galilei, 1564-1642

·He improved the telescope

·He discovered mountains on the moon, and the four Jupiter’s moons

Isaac Newton, 1642-1727

· Newtonian telescope

· Law of gravity
Laws:
 -1. Inertia
 -2. F=Ma

 -3. Every action has an equal and opposite reaction.

Halley, 1656-1742

· He discovered Halley’s Comet

Albert Einstein, 1879-1955

· He revolucioned the world of physics

· His theories of relativity are a new way to understand space and gravity