Chapter 4

Copernican

Revolution

1. Greek Astronomer Ptolemy

2. Dawn of Modern Astronomy

3. Copernicus

4. Bruno

5. Tycho

6. Kepler

7. Galileo

8. Newton

Outline

Ptolemaic UniversePtolemy’s Universe

• The Earth is at the center of the

cosmos.

• The Earth is a sphere.

• The Earth does not move.

• Planets revolve around the

Earth

• The celestial realm is spherical,

and moves in circular orbits.

• The planets move in epicycles,

circles within circles.

Middle AgesMiddle Ages

Unfortunately, during the next thousand-odd years a vast majority

of this information was lost, ignored, or “misplaced.” This was

largely due to two factors:

1. the violent nature of these times, and

2. a heavy religious influence on ruling bodies.

Up to this point, it was still 'common-knowledge' that the Earth was

the centre of the universe.

Early Classical Astronomers

Nicolaus Copernicus 1473-1543, Polish

Tycho Brahe 1546-1601, Danish

Thomas Digges 1546-1595, English

Giordano Bruno 1548-1600, Italian

Edmond Halley 1656-1742, English

Galileo Galilei 1564-1642, Italian

Johannes Kepler 1571-1630, German

John Babtist Riccioli 1598-1671, Italian

Giovanni Cassini 1625-1712, Italian-born French

Christiaan Huygens 1629-1695, Dutch

Sir Isaac Newton 1643-1727, English

Nicolaus Copernicus 1473-1543, Polish

Tycho Brahe 1546-1601, Danish

Thomas Digges 1546-1595, English

Giordano Bruno 1548-1600, Italian

Edmond Halley 1656-1742, English

Galileo Galilei 1564-1642, Italian

Johannes Kepler 1571-1630, German

John Babtist Riccioli 1598-1671, Italian

Giovanni Cassini 1625-1712, Italian-born French

Christiaan Huygens 1629-1695, Dutch

Sir Isaac Newton 1643-1727, English

Copernican Revolution

The Copernican Revolution refers to the paradigm

shift away from the Ptolemaic model of the heavens,

which postulated the Earth at the center of the

universe, towards the heliocentric model with the Sun

at the center of our Solar System.

It was one of the starting points of the Scientific

Revolution of the 16th Century.

Paradigm - generally accepted model of how ideas relate to one

another

Copernican Revolution

Nicolaus Copernicus

• (19 February 1473 – 24 May

1543) was a Polish doctor,

Diocesan Administrator (official

of the Catholic Church), and

amateur astronomer.

• He studied the Ptolemaic model

and found it convoluted and

inaccurate.

Nicolaus Copernicus

• Copernicus' epochal book, De revolutionibus orbium

coelestium (On the Revolutions of the Celestial Spheres),

published just before his death in 1543.

• It is often regarded as the starting point of modern astronomy

and the defining epiphany that began the scientific revolution.

Nicolaus CopernicusCopernicus' heliocentric theory is based upon some of the

following assumptions:

•The Earth is not the center of

the universe, but only of the

lunar sphere.

•The sun is the center of the

universe.

•The planets orbit the Sun in

perfectly circular orbits.

•Whatever motion appears in

the celestial sphere , arises

from the Earth's motion.

Nicolaus CopernicusCopernicus' heliocentric theory is based upon some of the

following assumptions:

•The apparent retrograde and direct motion of the planets

arises not from their motion but from the Earth's.

•The planets move at different speeds.

•Thus a planet seems to go into reverse when the Earth

passes by it in its orbit.

Nicolaus Copernicus

Nicolaus Copernicus

The ideas of Copernicus made astronomy much simpler, but

more evidence was needed for astronomers to accept his ideas.

This evidence was first provided by Galileo.

Copernicus' heliocentric theory is based upon some of the

following assumptions:

Nicolaus Copernicus

Archaeologists reported they have identified the remains of

Nicolaus Copernicus.

Copernicus died at age 70 in 1543.

A Polish archaeologist told a news conference forensic

reconstruction of the skull his team found in 2005 buried in a

cathedral in Frombork, Poland, bears striking resemblance to

portraits of the 16th century astronomer.

The reconstruction shows a broken nose and other features that

resemble a self-portrait of Copernicus, and the skull bears a cut

mark above the left eye that corresponds to a scar in the painting.

Giordano Bruno

Giordano Bruno (1548 – February 17, 1600), born Filippo

Bruno, was an Italian Dominican friar, philosopher,

mathematician and astronomer.

In astronomy he is best

known as a proponent of

the infinity of the universe.

His cosmological theory

identified the Sun as just

one of an infinite number

of independently moving

heavenly bodies.

Giordano Bruno

• He is the first European

to have conceptualized

the universe as a

continuum.

• The stars we see at

night are identical in

nature to the Sun.

• He had no scientific

data to support his

claim.

Giordano Bruno

In the 19th and early 20th centuries, commentators

focusing on his astronomical beliefs regarded him as a

martyr for free thought and modern scientific ideas.

Giordano Bruno

Charges brought against Bruno by the Inquisition:

• Holding opinions contrary to the Catholic Faith and

speaking against it and its ministers.

• Holding erroneous opinions about the Trinity.

• Holding erroneous opinions about Christ's divinity and

Incarnation.

• Holding erroneous opinions about the Mass.

• Claiming the existence of a plurality of worlds and their

eternity.

• Believing in reincarnation of the human soul into animals.

• Dealing in magic and divination.

• Denying the Virginity of Mary.

Giordano Bruno

After being found guilty of heresy in 1600 by the Roman

Inquisition, he was burned at the stake.

Giordano Bruno

• Recent assessments suggest

that his ideas about the

universe played a small role in

his conviction before the

Inquisition.

• Bruno was a martyr for magic

and hermetic philosophy, and

not for free thinking and support

of the Copernican System.

Tycho Brahe

Tycho Brahe

(14 December 1546 – 24 October 1601),

born Tyge Ottesen Brahe de Knudstrup,

was a Danish nobleman known

for his accurate and

comprehensive astronomical

and planetary observations.

The Man with the Golden Nose.

Tycho Brahe

•It had been maintained since antiquity that the world

beyond the Moon's orbit was eternally unchangeable.

• On 11 November 1572, Tycho observed a NEW very

bright star in the constellation Cassiopeia.

Tycho Brahe

•Tycho’s star was a

Supernova.

•Now named SN 1572

(Supernova of 1572).

•The appearance of the

supernova caused

considerable concerns

by the general public.

This is an image of the remnant of

Tycho’s Supernova.

Tycho Brahe

•Through his observations, Tycho

was able to prove that the new

celestial body was a fixed star in

the stellar sphere beyond all the

planets.

•In 1573 he published a small

book, De nova stella thereby

coining the term nova for a "new"

star.

•We now classify this star as a

supernova and we know that it is

7500 light-years from Earth.

Tycho Brahe

•This discovery was

decisive for his choice of

astronomy as a profession.

•Tycho was strongly critical

of those who dismissed the

implications of the

astronomical appearance.

•In the preface to De nova

stella, he wrote, “Oh thick

wits. Oh blind watchers of

the sky".

Tycho Brahe

• Tycho's observations of stellar and planetary

positions were noteworthy both for their

accuracy and quantity.

• Before his time, the accuracy was on the

order of 12 arc minutes.

Tycho Brahe

• He aspired to a level of accuracy in his

estimated positions of celestial bodies of

being consistently within 1 arcminute of their

real celestial locations.

• In reality, his accuracy was very close –

approximately 1.5 arcminutes (1' 30”).

Tycho Brahe

Tycho's observations of

stellar and planetary

positions were noteworthy

both for their accuracy and

quantity.

He achieved this high level of

accuracy by his very keen

eye sight and his superior

instruments.

Tycho Brahe

Images of

Tycho’s

sextants.

Sextants for

astronomical

observations

were used

primarily for

measuring

the positions

of stars.

Tycho BraheSextants for astronomical observations were used

primarily for measuring the positions of stars.

Tycho Brahe

Tycho’s Quadrant is

a rectangular division

of the celestial sphere

that is used for

constellation

navigation.

Tycho Brahe

An armillary sphere

(as spherical

astrolabe) is a

model of the

portions of the

celestial sphere.

Tycho Brahe

Tycho’s

Celestial Globe

Tycho Brahe

Tycho’s Great

Equatorial

Armillary

Tycho Brahe

Tycho’s Wall

Quadrant at

Hevn

Tycho Brahe

Tycho advocated an

alternative to the Ptolemaic

geocentric system, a geo-

heliocentric system now

known as the Tychonic

system.

In this system, the five known

planets orbit the Sun.

The Sun (and the 5 planets)

orbit the Earth.

Tycho's model of the Earth

does not rotate daily, but is

static.

Tycho Brahe

Tycho Brahe

In this system, the five known planets orbit the Sun.

The Sun (and the 5 planets) orbit the Earth.

Tycho's model of the Earth does not rotate daily, but is static.

Tycho Brahe

King Frederick II of Denmark gave Tycho the island of

Hven.

An

island of

about 3

square

miles

Tycho Brahe

On Hven,

Tycho built

Uraniborg in

1576.

Uraniborg was

a palatial home

and

observatory.

Tycho Brahe

The building

was dedicated

to Urania, the

Muse of

Astronomy and

named

Uraninborg,

"The Castle of

Urania.”

Tycho Brahe

•The wind caused instruments in the upper floors of

Uraniborg to twist.

•To combat this, Tycho built Stjerneborg in 1581.

•Stjerneborg “castle of the stars”

•Stjerneborg is an series of underground observatories

with removable roofs.

Tycho Brahe

•The wind caused

instruments in the

upper floors of

Uraniborg to twist.

•To combat this,

Tycho built

Stjerneborg in 1581.

•Stjerneborg is an

series of

underground

observatories with

removable roofs.

Tycho Brahe

•The wind caused

instruments in the

upper floors of

Uraniborg to twist.

•To combat this,

Tycho built

Stjerneborg in 1581.

•Stjerneborg is an

series of

underground

observatories with

removable roofs.

Tycho Brahe

•The wind caused

instruments in the

upper floors of

Uraniborg to twist.

•To combat this,

Tycho built

Stjerneborg in 1581.

•Stjerneborg is an

series of

underground

observatories with

removable roofs.

Tycho Brahe

•The wind caused

instruments in the

upper floors of

Uraniborg to twist.

•To combat this,

Tycho built

Stjerneborg in 1581.

•Stjerneborg is an

series of

underground

observatories with

removable roofs.

Tycho Brahe

•The wind caused

instruments in the

upper floors of

Uraniborg to twist.

•To combat this,

Tycho built

Stjerneborg in 1581.

•Stjerneborg is an

series of

underground

observatories with

removable roofs.

Tycho Brahe

However, with the death

of his sponsor, King

Frederick, Tycho fell from

favor in the Danish Royal

Court. Tycho was forced

to leave Uraniborg.

Tycho Brahe

• On February 4, 1600, Tycho

gained an assistant of sorts,

the talented mathematician

Johannes Kepler.

• Kepler was not as skilled as

Tycho when it came to making

observations on the sky. He

had poor eye sight.

Tycho Brahe

Kepler was remarkably gifted at geometry and was

ideally suited to making sense out of the observations

Tycho had recorded.

Tycho Brahe• Tycho suddenly contracted a bladder ailment after

attending a royal banquet in Prague.

• He died eleven days later, on 24 October 1601.

•• According to

Kepler's first hand

account, Tycho had

refused to leave the

banquet to relieve

himself because it

would have been a

breach of etiquette.

• Before dying, he

urged Kepler to

adopt the Tychonic

planetary system.

Tycho Brahe

• It has been long believed that

Tycho died from kidney failure

or a ruptured bladder.

• In 1901 scientists opened his

grave and claimed to have

discovered mercury in his

remains.

• This presents the possibility

that Tycho was murdered.

• The primary suspect would

have been

Johannes Kepler.

Tycho Brahe

• In 2010 Tycho’s remains were exhumed to study.

• A chemical analysis of the corpse indicated that

mercury poisoning did not kill Tycho.

• Additionally, the Golden Nose was probably made of

brass.

Tycho Brahe

Johannes Kepler

Johannes Kepler

(December 27, 1571 –

November 15, 1630)

was a German

mathematician,

astronomer and

astrologer.

He was a key figure in

the 17th century

scientific revolution.

Johannes Kepler

Unlike his master, Tycho, Kepler was a Copernican.

Tycho’s family was very reluctant in supplying Kepler

with the data he desired to prove the Copernican

system.

So, Kepler had only one choice (at least in his mind):

Kepler stole the data.

Johannes Kepler

Kepler claimed to have had an epiphany on July 19,

1595.

He reasoned that there might be a geometric basis of

the universe and attempted to find a relation between

the five extraterrestrial planets known at that time and

the five Platonic solids.

All the sides of a Platonic solid are congruent.

Johannes Kepler

In the same year (1596),

Kepler published his

theory in Mysterium

Cosmographicum (The

Cosmographic Mystery),

was the first published

defense of the

Copernican system.

Johannes Kepler

•In Mysterium

Cosmographicum,

Kepler laid out a model

of the solar system in

which the five solids

were set inside one

another.

•The solids were

separated by a series

of spheres.

•Each sphere

represented a planet’s

orbit.

Johannes Kepler

Kepler’s CosmologyPlanet Name Platonic Solid

Number of sides

Mercury Inside the Octahedron

8

Venus Octahedron 8

Earth Icosahedron 20

Mars Dodecahedron 12

Jupiter Tetrahedron 4

Saturn Cube 6

The six spheres each corresponded to one of the planets

(Mercury, Venus, Earth, Mars, Jupiter, and Saturn).

Johannes Kepler

After working with Tycho’s data, Kepler reluctantly

concluded that his geometric scheme was wrong and

had to be abandoned.

Johannes Kepler

• In 1609 Kepler

published

Astronomia nova

(New Astronomy).

• It contains the

results of his ten-

year long

investigation of the

motion of Mars.

Johannes Kepler

Kepler bases his investigations upon the observations of

Danish astronomer Tycho Brahe.

Astronomia nova is divided into 5 parts:

Part I Tycho Brahe's data is vigorously investigated for embedded

errors.

Part II The errors of previous models of the universe is discussed.

Part III Kepler’s discussion of gravitation.

Part IV Kepler discovers that the orbit of Mars cannot be circular.

Part V Kepler's conjecture that the Sun follows some orbit across

the stars.

Johannes KeplerIn Astronomia nova Kepler records the discovery of the

first two of the three principles known today as Kepler's

Laws of Planetary Motion, which are:

The First Law: That the planets move in elliptical orbits

with the sun at one focus.

Johannes Kepler

An ellipse is a distorted circle. Has a center and

two foci.

Johannes Kepler

The orbits of the planets are ellipses with the Sun

at one focus.

Eccentricity e = c/a

c

Johannes Kepler

The orbital eccentricity of an astronomical body is the

amount by which its orbit deviates from a perfect

circle, where 0 is perfectly circular.

c

a

Orbits of planets are virtually indistinguishable

from circles:

Johannes Kepler

Planet Eccentricity

Mercury 0.21

Venus 0.01

Earth 0.02

Mars 0.09

Jupiter 0.05

Saturn 0.06

Uranus 0.05

Neptune 0.01

Pluto 0.25

Mars

Johannes KeplerThe Red circular line is Mars’ orbit. The Blue circle is a

perfect circle.

Kepler could not make Mars’ orbit fit the requirements

of a circular path.

However, the green ellipses fits Mars’ the orbit

perfectly.

Johannes KeplerThe Second Law: The orbital speed changes as the

planet moves through its orbit. As the planet

approaches the sun, its speed increases. As the

planet retreats from the sun, its speed decreases.

Johannes KeplerThe Second Law can also stated as:

That the speed of the planet changes at each

moment such that the time between two positions is

always proportional to the area swept out on the orbit

between these positions.

Johannes Kepler

•However, Kepler's "area-time principle" was very

difficult to use.

•A planet’s position could not be accurately

determined because the planet’s speed was

constantly changing.

•This paradox, referred to as the "Kepler Problem,"

could only be solved after the development of

calculus.

Johannes Kepler

Kepler discovered his third law

and published the findings in

the 1619 book, Harmonices

Mundi (The Harmony of the

World).

Johannes Kepler

The Third Law: In its simplest form, if you know how

far a planet is from the sun, you know how long its

year is.

The square of the time of 1 year of a planet is directly

proportional to the cube of the radius of its orbit."

Symbolically:

P2 ≈ a3

where P is the time of orbit period (in years) and a is

the radius of the orbit (in AU).

Johannes Kepler

Name

Orbital

radius

(AU)a3

Orbital

period

(years)P2

Mercury 0.387 0.06 0.24 0.06

Venus 0.723 0.38 0.62 0.38

Earth 1 1.00 1 1.00

Mars 1.52 3.5 1.88 3.5

Jupiter 5.2 140.6 11.859 140.6

Saturn 9.54 868 29.46 868

Uranus 19.229 7110 84.32 7110

Neptune 30.061 27165 164.79 27156

Johannes Kepler•While medieval philosophers spoke metaphorically

of the "music of the spheres", Kepler discovered

physical harmonies in planetary motion.

•He found that the difference between the maximum

and minimum angular speeds of a planet in its orbit

approximates a harmonic proportion.

Johannes Kepler

• Kepler was envious that Tycho had discovered a new

star (supernova).

• In 1604, Kepler observed a new star.

Johannes Kepler

• He recorded the finding

in De Stella nova in

pede Serpentarii (On

the New Star in

Ophiuchus's foot)

• It is the last supernova

to explode in our galaxy.

This is an image of the remnant of

Kepler’s Supernova.

Galileo Galilei

Galileo Galilei

(15 February 1564 –

8 January 1642)

Galileo was an Italian

physicist,

mathematician,

astronomer and

philosopher.

He played a major role

in the Scientific

Revolution.

Galileo GalileiAt the same time Kepler was making his

groundbreaking discoveries, Galileo was single-

handedly bringing on the downfall of naked-eye

astronomy, using a new invention called the

telescope.

Galileo Galilei

Galileo has been called:

The Father of Modern

Observational Astronomy

The Father of Modern Physics

The Father of Science

The Father of Modern Science.

Galileo GalileiGalileo did not invent the telescope, but in 1609 he

became the first person to use the telescope for

astronomy.

Galileo Galilei

Hans Lippershey, also known

as Johann Lippershey or

Lipperhey, was a German-

Dutch lensmaker commonly

associated with the invention

of the telescope, although it

is unclear if he was the first

to build one

Galileo Galilei

Galileo made a

number of

discoveries with the

telescope. In 1610,

Galileo published

these findings in a

book called

Sidereus Nuncius

(The Sidereal

Messenger).

Galileo GalileiHe discovered moons orbiting Jupiter. This showed

that the Earth is not the center of all motion.

These are Galileo’s

records of his

observations.

This is

probably

what he

saw.

This is

what we

see today.

Galileo Galilei• Draft of a letter to

Leonardo Donato, Doge

of Venice, August, 1609,

and Notes on the Moons

of Jupiter, January 1610.

• It reflects a pivotal

moment in Galileo's life

that helped to change

our understanding of the

universe.

Galileo Galilei

•The four moons (Io,

Europa, Ganymede, and

Callisto) are called the

Galilean Moons.

•Originally, Galileo

wanted to name them

after Medici brothers

(Cosimo, Francesco,

Carlo, and Lorenzo).

•Cosimo dé Medici was

the Grand Duke of

Florence.

Galileo Galilei

He observed mountains,

craters, and what looked like

oceans on the Moon.

He saw that the Moon was a

world of hills, valleys,

mountains and planes, not a

perfect, heavenly light.

Galileo Galilei•He also discovered Saturn’s Rings. Although he

initially thought that the rings were "handles" or large

moons on either side of the planet.

•He said "I have observed the highest planet [Saturn] to

be tripled-bodied.”

Galileo Galilei

Galileo in Art• Painted in 1636 (shortly after

Galileo’s trial and

recantation), Peter Paul

Rubens created “Saturn

Devours His Son.”

• In the background, Rubens

included Galileo’s discovery

that “the star of Saturn is not

a single star, but is a

composite of three.”

Galileo Galilei• In 1612 Galileo was astounded when he

found that the rings he first observed a

couple of years earlier had now

disappeared.

• The rings were, in fact, edge-on from

Earth's perspective.

• Galileo inadvertently became the first

person to observe Saturn’s rings on-edge.

Galileo GalileiHe observed the phases of Venus. This was predicted

by the heliocentric model, but not the geocentric model.

These are Galileo’s

records his

observations.

Phases as Galileo may

have seen them.

Galileo Galilei

The Ptolemaic View only allows for the New or

Crescent phases of Venus.

Galileo GalileiHe also found imperfections on the supposedly perfect

body of the Sun. He discovered sunspots, and found

that the Sun rotated, like an ordinary, material object.

Galileo Galilei

He resolved the

Milky Way into a

multitude of stars,

showing that stars

were more distant

than had been

imagined, and that

some of them

were not visible to

the human eye.

Galileo Galilei

These findings were strong evidence

supporting heliocentrism (Sun-centered

universe) which was, at the time, against

the teachings of the Bible and the

Catholic Church.

Galileo was then warned by the church

not to teach heliocentrism as fact, only as

a theory.

Galileo Galilei

•The climax of Galileo's

publishing was the book,

Dialogo sopra i due

massimi sistemi del

mondo, tolemaico

copernicano (Dialogue

Concerning the Two Chief

World Systems, Ptolemaic

and Copernican).

•Published in 1632, it

compares the Copernican

system with the traditional

Ptolemaic system.

Galileo Galilei

The book is presented as a

series of discussions, over a

span of four days, among two

philosophers and a layman:

•Salviati argues for the

Copernican position and

presents some of Galileo's

views directly.

•Sagredo is an intelligent

layman who is initially

neutral.

•Simplicio, a dedicated

follower of Ptolemy and

Aristotle, presents the

traditional views and the

arguments against the

Copernican position. This engraving contains the images of

Aristotle, Ptolemy, and Copernicus.

Galileo Galilei

Biblical references Psalm 93:1, Psalm 96:10, and

1 Chronicles 16:30 include text (depending on the

translation) stating that "the world is firmly

established, it cannot be moved."

In the same manner, Psalm 104:5 says, "the Lord

set the Earth on its foundations; it can never be

moved."

Further, Ecclesiastes 1:5 states that "And the Sun

rises and sets and returns to its place".

One of the main reasons for Galileo's

condemnation in 1633 was his attack on the

Aristotelian doctrine of matter rather than his

defense of Copernicanism.

Galileo Galilei

Galileo was called to Rome in 1633 to face the Roman

Inquisition.

On 22 June 1633 Galileo, having been found guilty of

“vehemently suspect of heresy” and was forced to make a

“confession” to the Cardinals of the Holy Office of the Church.

Galileo Galilei

The sentence of the Roman Inquisition was in three essential

parts:

1. Galileo was required to "abjure, curse and detest" the

opinions that the universe was heliocentric.

Galileo Galilei

The sentence of the Roman Inquisition was in three essential

parts:

2. He was sentenced to formal imprisonment at the pleasure of

the Inquisition. On the following day this was commuted to

house arrest, which he remained under for the rest of his life.

Galileo Galilei

The sentence of the Roman Inquisition was in three essential

parts:

3. His offending Dialogue was banned, and publication of any

of his works was forbidden.

Galileo Galilei

• According to popular legend,

after recanting his theory,

Galileo allegedly muttered the

rebellious phrase Eppur si

muove (And yet it moves).

However, there is no evidence

that he actually said this or

anything similar.

• The first account of the legend

dates to a century after his

death.

Galileo Galilei

In 1835, 202 years after it was banned,

Galileo's Dialogue Concerning the Two

Chief World Systems is removed from the

Vatican's list of banned books.

Galileo Galilei

357 years later.

Thanks to his intuition as a brilliant physicist and by relying on

different arguments, Galileo, who practically invented the

experimental method, understood why only the sun could function

as the centre of the world, as it was then known, that is to say, as

a planetary system. The error of the theologians of the time, when

they maintained the centrality of the Earth, was to think that our

understanding of the physical world's structure was, in some way,

imposed by the literal sense of Sacred Scripture....

– Pope John Paul II - November 4, 1992

Sir Isaac Newton

Sir Isaac Newton

4 January 1643 –

31 March 1727

[Old Calendar System]

25 December 1642 –

20 March 1726

He was an English

physicist, mathematician,

astronomer, natural

philosopher, alchemist,

and theologian.

Sir Isaac Newton

Isaac Newton is

considered by many

scholars to be one of the

most influential people in

human history.

Sir Isaac Newton

Sir Isaac Newton

Sir Isaac Newton

Sir Isaac Newton

In this work, Newton stated the three universal laws of

motion that were not to be improved upon for more than

200 years.

He used the Latin word gravitas (weight) for the effect

that would become known as gravity, and defined the

law of universal gravitation.

Sir Isaac NewtonIn the same work, Newton presented a calculus-like

method of geometrical analysis and gave the first

analytical determination of

• inferred the oblateness of the Earth (slightly

flattened sphere).

• accounted for the precession of the equinoxes as a

result of the Moon's gravitational attraction on the

Earth

• initiated the gravitational study of the irregularities in

the motion of the moon

• and much more

Note: We will spend an entire chapter exploring

Newton’s Law of Universal Gravitation and its

implications in astronomy.

TermsNicolaus Copernicus

On the Revolutions of the

Celestial Spheres

heliocentric theory

Retrograde motion

Giordano Bruno

plurality of worlds

Tycho Brahe

SN 1572

De nova stella

Sextants

Quadrant

armillary sphere

Wall Quadrant

Tychonic System

Uraniborg

Stjerneborg

Johannes Kepler

Platonic solids

The Cosmographic Mystery

New Astronomy

Kepler’s 1ST Law of Planetary Motion

Ellipse

Eccentricity

Kepler’s 2ND Law of Planetary Motion

Kepler’s 3RD Law of Planetary Motion

The Harmony of the World

SN 1604

Galileo Galilei

Telescope

Galileo’s planetary/lunar/solar discoveries

The Sidereal Messenger

Dialogue Concerning the Two Chief World

Systems, Ptolemaic and Copernican

Roman Inquisition

Isaac Newton

The Principia

Copernican Revolution

The End