Unit 3: Ancient Greek Astronomy

What was Ancient Greece’s time period?

3000 B.C.E. ↔ 300 C.E.

What happened at around 3000 B.C.E?

Greeks arrived at Aegean Peninsula

What happened at around 750 B.C.E?

started recorded history

• founded Rome

• wrote alphabet

What time period was set in between 750 B.C.E. & 480 B.C.E?

Archaic Period

What characterized the time period set in between 750 B.C.E. & 480 B.C.E?

• city states loosely united & expanded to new territories

What time period was set in between 480 B.C.E. & 323 B.C.E?

Classical Period

What characterized the time period set in between 480 B.C.E. & 323 B.C.E?

• Macedonia dominated

• Alexander the Great expanded to Egypt & Babylon

What time period was set in between 323 B.C.E. & 156 B.C.E?

Hellenistic Period

What characterized the time period set in between 323 B.C.E. & 156 B.C.E?

• culture expanded to Middle East & Egypt

What time period was set in between 156 B.C.E. & 30 B.C.E?

Greco-Roman Period

What characterized the time period set in between 156 B.C.E. & 30 B.C.E?

• Greek empire joined Roman Republic

• last Egyptian Greek ruler Cleopatra VVI died

True or False: Ancient Greece is the 1st documented group taking astronomy beyond tracking time & astrology & religion.

True.

What were some possible reasons for Greeks taking astronomy beyond tracking time & astrology & religion?

• fragmented geography

• decentralized rule

• established first higher education

What are the word origins of “academy?”

1st school location

• just outside Athens

What is the identity of the 1st school’s creator?

Plato

What philosopher group originated in 600 B.C.E?

Ionian

What philosopher group originated in 500 B.C.E?

Pythagorean

What are some examples of geocentrists?

• Plato

• Eudoxus

• Aristotle

• Appollonius

• Hipparchus

• Ptolemy

What are some examples of heliocentrists?

• Philolaus

• Herakleides

• Aristarchus

What were the featured Ionian philosophers’ birthplace?

Miletus, Ionia

Which featured Ionian philosopher taught the other Ionian philosopher?

Thales taught Anaximander

What was Thales’ birth date?

625 B.C.E.

What method did Thales use to learn about science?

travel

• Middle East

• Egypt

What did Thales recognize about Greek & Egyptian / Babylonian explanations?

• explained phenomena with different god & mood

• sought explanation beyond god

What did Greeks associate with earthquakes?

angry Poseidon

What did Egyptians associate with earthquakes?

laughing Geb

What did Thales associate with earthquakes?

Earth floated on water

What was the reason for Thales’ association with earthquakes?

large wave moved ground

What was Thales’ method for gaining popularity?

demonstrating natural events’ predictability

What was the start date of the Medes & Lydians war?

600 B.C.E.

What ended the Medes & Lydians war on 585 B.C.E?

eclipse

What did Thales say to both army generals?

solar eclipse’s going to occur

What did Greeks associate with solar eclipses?

Zeus randomly blocked sun

What was the identity of the observer that wrote the legend on 585 B.C.E?

Herodotus

What was Anaximander’s birth date?

610 B.C.E.

What is the identity of the 1st cosmologist?

Anaximander

What does “cosmology” mean?

• universe study explaining origin & method by creating model organizing known universe & motion pattern

What was Anaximander’s cosmology?

wheels around cylinder Earth

What did Anaximander believe about Earth’s absolute position?

• finite ground

• floating in space

True or False: Anaximander explained the reason for Earth’s absolute position.

False: Anaximander did not explain why Earth was floating in space.

What astronomical concepts did Anaximander’s cosmology explain?

• day cycle

• moon cycle

• eclipse cycle

• season cycle

What revolution did Anaximander have about the thought process?

model could be proposed & tested

What was the identity of Pythagoras’ teacher?

Anaximander

What date was Pythagoras being taught by his teacher?

550 B.C.E.

What is Pythagoras’ birth date?

570 B.C.E.

What is Pythagoras’ birthplace?

Samos

What did Pythagoras’ followers believe?

• math cult

• understand science = understand god

What were some examples of Pythagorean rules?

• communal

• vegetarian

• specific on science

• men = women

What was the reason for Pythagoras’ leadership?

only one hearing celestial music

What comprises the Pythagoras & Blacksmith legend?

• walked past blacksmith forge & wondered why some sounds were harmonious / unharmonious

  • method: measured dimensions

  • result: bar length determined sound, musical pitch followed natural law so universe followed natural law

    • if 2 bar lengths were simple ratio, harmonious

    • if 2 bar lengths were not simple ratio, unharmonious

What did “cosmos” mean to Pythagoras?

• universe follows equation laws

What is the word origin of “cosmos?”

order

• Greek

What Pythagorean legend connected music and celestial motion?

music equation = celestial motion equation

What beliefs did Pythagoreans have about perfection?

• celestial bodies move in perfect circles

• Earth = sphere

What reason did Pythagoreans have to choose a perfect shape?

• simplest & purest geometric shape

What evidence did Pythagoreans have for a round Earth?

• horizon disappearance

• lunar eclipse

• star shift

What is the reason that horizon disappearance is Pythagorean evidence?

if flat Earth, decrease size then fall off of edge / fade to 1 point

v.s.

if round Earth, disappear bottom-first

• on curved surface, top remains visible as object goes over horizon

What is the reason that a lunar eclipse is Pythagorean evidence?

Earth’s round shadow on Moon

What is the reason that a star shift is Pythagorean evidence?

if flat Earth, specific rate based on walk speed

v.s.

if round Earth, different rate based on walk speed

• constellation shift = travel distance

True or False: It is a misconception that European colonizers in the 1500s were worried that they would fall off of the edge of Earth.

True.

What was the Pythagorean persecution time period?

500 B.C.E. ↔ 400 B.C.E.

Which philosopher group followed Anaximander?

eliocentrism

What is the identity of the 1st person to suggest Earth moves through space?

Philolaus

What does Philolaus suggest Earth orbits, and at what frequency?

Central Fire 1x a day

True or False: Greece faced the celestial body that Earth orbited.

False: Greece faced away from the Central Fire.

What did Aristotle claim about the celestial body in between the Central Fire & Earth?

added to bring celestial body number to 10

What was Philolaus’ cosmology?

• Central Fire → Counter-Earth & Earth orbit Central Fire once a day → Sun orbits Central Fire once a year → fixed stars

[image]

What did Herakleides change about Herakleides’ cosmology?

• rid Central Fire

  • other side of Earth did not see Central Fire

• rid Counter-Earth

• put Mercury & Venus in orbit around Sun

What was Herakleides’ reason for orbiting celestial bodies around the Sun?

Mercury & Venus make nearer loop to rising / setting sun → motion & brightness

What was Aristarchus’ birth date?

310 B.C.E.

What was Aristarchus’ birthplace?

Samos

What are Aristarchus’ famous texts?

1. “On the sizes & distances of the Sun & Moon”

2. heliocentric universe

What text gained Aristarchus fame?

“On the sizes & distances of the Sun & Moon”

True or False: Aristarchus’ results were incorrect but his methods were correct.

True.

What did Aristarchus do with a lunar eclipse?

monitored Earth’s shadow size on Moon

What did Aristarchus determine with a lunar eclipse?

Moon size < Earth size

What was the Moon’s size relative to Earth, according to Aristarchus?

1/2 of Earth

What is the Moon’s size relative to Earth?

1/4 of Earth

What did Aristarchus do with Sun’s distance compared to the Moon?

• waited for 3rd quarter moon phase

  • because Sun’s in lit direction

• solved right triangle

  • measured ∠A (Sun ↔ Moon angle) using quadrant

• used Pythagorean theorem

What did Aristarchus determine with Sun’s distance compared to the Moon?

Sun’s farther than Moon

What was Earth’s angle in between the Sun & Moon, according to Aristarchus?

87°

What is Earth’s angle in between the Sun & Moon?

89.9°

What was the Moon’s distance from Earth relative to the Sun, according to Aristarchus?

1/19 of Sun’s distance

What is the Moon’s distance from Earth relative to the Sun?

1/382 of Sun’s distance

True or False: Aristarchus determined the Moon’s & the Sun’s distances.

False: Aristarchus did not determine the Moon’s or the Sun’s distances.

What was Earth’s size relative to the Sun, according to Aristarchus?

1/10 of Sun

What is Earth’s size relative to the Sun, according to Aristarchus?

1/100 of Sun

What method did Aristarchus to determine Sun’s size relative to Earth?

• Sun > Moon

• Moon < Earth

  • Sun & Moon have similar apparent size

so

• Sun > Earth

What happened to Aristarchus’ 2nd famous text?

lost but spoken / written about for centuries

What question does Aristarchus’ 2nd famous text answer?

“Is Earth at centre if Sun is the largest celestial body?”

What answer does Aristarchus’ 2nd famous text have for the question it asks?

no

• Moon orbits Earth

  • only celestial body that doesn’t have weird pattern

What date did the heliocentric track end?

100 B.C.E.

What was the reason for the heliocentric track end?

Aristarchus wasn’t interested in followers