ASTRONOMY AND THE BIRTH OF MODERN

SCIENCE

ANCIENT ASTRONOMY

Human SurvivalPredict when to plant crops Indian ruins line up with Summer and winter solstice and

spring /fall equinoxes

Read the stars to navigate ocean

OMENS

1054 AD Chinese see Supernova explosion (remnants are still detectable today)

GEOCENTRIC UNIVERSE –EARTH CENTERED

Aristotle Greek philosopher’s (382-422 AD)

Objects moved around the earth in a perfect circle

Didn’t explain

1. varying planet brightness

2. Retrograde motion (apparent backwards motion )

HELIOCENTRIC MODEL (SUN-CENTERED UNIVERSE Nicholas Copernicus (1473-1543)Earth spins on its axis and orbits the sun, only moon orbits earth

Explains daily light dark and seasonal changes as well as retrograde motion and planet brightness

Johannes Kepler (1571-1630) and Tycho Brahe (1546-1601)Kepler used Brahe’s and Copernicus’s observations to

create mathematical models that described the orbits of the planets and their distance from the sun.

MODERN ASTONOMY

Galileo Galilei (1564-1642)

1. First to use telescope to see

A. Sunspots that moved across the sun showing sun’s rotation

B. Jupiter’s 4 main moons, showing moons revolved around something other than Earth

C. Phases of Venus

MODERN ASTRONOMY

Isaac Newton (1642-1727) Born the day Galileo died

Laws of Motion described how and why planets moved the way they did

1. !st Law Inertia

2. 2nd Law F= ma

3. 3rd Law: For one force there is an equal and opposite force.

THE EXPANDING UNIVERSE

Edwin Hubble (1889-1953)

The Hubble Expansion Law

In 1929, Edwin Hubble announced that almost all galaxies appeared to be moving away from us. This phenomenon was observed as a redshift of a galaxy's spectrum. This redshift appeared to have a larger displacement for faint, presumably further, galaxies. Hence, the farther a galaxy, the faster it is receding from Earth.