7.1 Ancient Astronomy p. 271

Movement of objects through the night sky

rising and setting of the Sun

phases of the Moon

position of the stars changing with the seasons

Very consistent and measurable

Mayan pyramids functioned as

calendars

Used to make structure that functions as ‘calendar’

Early Calendars

Organized days into a schedule of larger units

of time (weeks, months, seasons, years)

shown as a table or chart

allowed people to predict events:

◦ seasons

◦ spring rains

◦ annual flooding of rivers and lakes

◦ location and migration of birds, insects, and

herds of animals

Early Civilizations With the invention of the calendar,

the first civilizations were born

WHY?

organized agriculture

more food

time and resources to develop

knowledge and skills in a variety of areas

Early Sky Observations

Fishers, mariners, and travellers used the fixed patterns of the stars

to help them navigate on land and water.

Early Astronomers

Our ancestors believed that the deities

(gods) ruled the skies

Changes in the heavens meant that the

gods might be getting restless.

Celestial objects: objects that exist in space (planet, star, Moon)

Celestial priests and priestesses studied these objects and learned

how to predict seasons and eclipses.

Mesopotamian Astronomers

Astronomers: scientists who study astronomy,

Astronomy: study of the night sky

The first astronomers were the Mesopotamians

kept detailed records of the sky as early as 6000 years ago

Years and Days

Revolution:

the time it takes an object to orbit another object

Year:

the number of days it takes Earth to make one

revolution around the Sun (365.25 days)

Rotation:

the turning of an object around an imaginary axis

running through it

Day:

the time it takes for Earth to make one rotation

(24 hours)

Early Clocks

Eg. sundial

tracked shadows to tell the time of day

Earth rotates

position of the Sun changes

sundial casts shadows in different directions

position of the shadow on the sundial tells

the TIME

Revolution and Rotation

Earth’s Shape

In the past, people thought the Earth was flat.

Two ancient Greek philosophers, Eratosthenes and Aristarchus

hypothesized that Earth was spherical

Based on 3 pieces of evidence

Evidence #1

The hull and then the masts of ships appeared to descend below the

horizon as ships sailed away.

Evidence #2

The appearance of the sky changed as travellers journeyed farther

north or south.

Evidence #3

During a lunar eclipse, the shadow of Earth on the moon was

curved.