Ancient Astronomy How have Humans come to Observe/Revere the heavens, and How Has it affected Human - PowerPoint Presentation

Ancient Astronomy How have Humans come to Observe/Revere the heavens, and How Has it affected Human
Ancient Astronomy How have Humans come to Observe/Revere the heavens, and How Has it affected Human

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Early Astronomy Humans have been fascinated by the sky for all time Constellations have helped people navigate tell stories are the gods that look over humanity Constellations are groupings of stars that form images much like seeing ID: 780907 Download


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Ancient Astronomy

How have Humans come to Observe/Revere the heavens, and How Has it affected Humanity?


Early Astronomy

Humans have been fascinated by the sky for all time.

Constellations have helped people navigate, tell stories, are the gods that look over humanity.

Constellations are groupings of stars that form images, much like seeing


in clouds

Each culture has different images/histories with constellations





“Big Bear”

“Big Dipper”

Not a constellation – called an asterism



There are 88 recognized constellations in Astronomy today

Some are only visible from the Northern Hemisphere, some only visible from the Southern Hemisphere

Some of the more recognizable ones in Northern Hemisphere are…




MinorOrionCanis Major




The constellations rise and fall at specific times on specific days in a yearly pattern

Their “motion” per day is due to the rotation of the Earth

Their “motion” per year is due to the revolution of the Earth about the Sun

Ancient Astronomers would be able to tell people when to plant/harvest crops, based on the where the constellations were located.


"When great Orion rises, set your slaves

to winnowing Demeter's holy grain

upon the windy, well-worn threshing floor.

Then give your slaves a rest; unyoke your team.

But when Orion and the Dog Star move

into the mid-sky, and Arcturus sees

The rosy-fingered dawn, then Perseus, pluck

The clustered grapes, and bring your harvest home.“Hesiod - Approx. 500 B.C.


Winter Constellations





Collection of 12 constellations along the plane where the Sun and all major objects of the Solar System revolve.



A pseudo-science that attempts to explain human behaviors based on where the sun/planets are in relation to the constellations of the zodiac

There is absolutely NO evidence that the positions of the planets has any bearing on our experiences/life history

The constellations, however, have historical significance and are maintained in modern astronomy.


Ancient Civilizations

Astronomy is one of the oldest sciences, and has been used by Humans for as long as history as been recorded

There have been several major contributors to Ancient Astronomy

Ancient Greeks




Native AmericanAncient EuropeanJust to name a few!!!


Mesoamerican Astronomy


400 A.D. Could predict eclipses, recorded positions of planets.

Astronomy was state-sponsored, and played a role in war, marriage, etc.

Their calendar was more accurate than the one the Europeans were using when they were conquered in the 1500’s

“New Year’s Day” was on July 26


, An observatory in Edzna, the sun passed directly overhead on this day.Chichén

Itzá - Mayan city in the Yucatan Peninsula





El Castillo – “the snake”



Caracol – “The Observatory”Windows in El Caracol line up with positions of Venus in the sky on an 8 year cycle.

Of 29 possible astronomical events (eclipses, equinoxes, solstices, etc..), there are 20 of them found in the structure.


El Castillo


El Caracol


Other Native American Structures

Casa Grande – Arizona

Believed to be an observatory

Some windows are aligned to Sun, Moon at specific times

Built in the 14


century AD, was abandoned by the 16

th centuryBuild by the Hohokam


Aztec Astronomy

Aztec Astronomy was strongly associated with religion and their moral code

Major cities were built based on astronomical observations

The orientations of structures were as well

The center of their beliefs was the Sun

Our Sun was the “fifth” one, the others having been destroyed by other events

The calendar stone --------------


Incan Astronomy

Religion and Astronomy were closely linked

The Sun and the Moon were both seen as God.

The Inca grouped stars into Constellations

They had both light and dark constellations (only civilization to do this!!!)

The Light constellations were inanimate

The Dark constellations were animate animals


Incan Astronomy

Example of “Dark” constellations – named after animals


– the Serpent


– the Toad


– the


Urcuchillay – the LlamaAtoq – the Fox

Machu Picchu – Ceremonial Site, Agricultural experimentation and Astronomical Observatory


Chinese Astronomy

As early as 2,000 B.C. – Were predicting eclipses

Were among the earliest astronomers in the world

Named stars – Created “Mansions” (Constellations)

Had 28 Mansions


Map – North Polar Region


Chinese Astonomy

Had records of Halley’s Comet and “guest stars”, which were supernovas

Had extensive records of the supernova that caused the Crab

Nebula (SN 1054)

Worked with Indian Astronomers during the Tang Dynasty (600-900 A.D.) as well as with Arab Astronomers during the Yuan Dynasty (1200-1400 A.D.)

Were open to the idea that the Earth was in motion, but no formal research was undertaken.


Greek Astonomy

Archaic Greek Astronomy

Literary references to stars and constellations


, Orion,


Major, Sirius, etc…

Works of Homer and Hesiod – 700-800 B.C.Some cosmic speculationAnaximander – 600 B.C.Cylindrical Earth, suspended – surrounded by fire

Philolaus – 400 B.C.Cosmos with Sun, Moon, Earth, and anti-Earth (Antichthon

) circling an unseen central fireEarly Greeks knew of the planets and their special place in our solar systemOrphism (religion) – 5th century B.C.

Earth is round, has an axis, rotates in a day, climate zones, etc…


Greek Astronomy

Greek Planets

5 planets or “wanderers” can be seen with the Naked Eye from Earth

Mercury – Hermes (messenger god)

Venus – Aphrodite (goddess of love)

Mars – Ares (god of war)

Jupiter – Zeus (king of the gods)

Saturn – Cronus (father of Zeus)Careful observations are needed to determine the planets and their locations

Early Greeks thought Venus was two different planets (one in the morning, one in the evening)Hesperius (“evening star”) and Phosphorus (“light-bringer”) – Pythagoras realized they were the same star.




The Pythagoreans placed astronomy among the 4 mathematical arts

Arithmetic, Geometry, Music and Astronomy



system involved…

A shift from stellar to planetary concernsThe creation of the “two-sphere” modelThe establishment of theories for planetary observations


Two Sphere Model

Geocentric (Earth centered) model

Two Regions

Spherical Earth – central and motionless

Heavenly realm – centered on Earth, made of multiple rotating spheres of



Plato – 8 heavenly spheres carrying the 7 planets and the fixed starsEudoxus – Used concentric spheres, tilting axes, and different periods of revolutions – was able to approximate the celestial appearances.

Unfortunately all his work was lost, so we only have secondary sources 


Two Sphere Model


– Added more spheres (up to 34 now!) to better describe the motion

Aristotle – Added “unrolling” spheres between each set to cancel the motions of the outer set, otherwise he believed the motion would be transferred to the inner planets

Had many critical flaws

Could not predict motions exactly

Could not explain why the planets changed apparent speed

Could not explain changes in brightness of planets


Hellenistic Astonomy

Apollonius of


introduced two new


Eccentric deferent – the spheres were slightly off-center from Earth

Deferent and Epicycle

Deferent is the circle carrying the planet around the EarthEpicycle is a small circle, which carries the planetThis allowed the model to explain “retrograde” motion, where the planet appears to move backwards against the ecliptic

Hipparchus Was aware of the extraordinary accuracy of the Babylonian Astonomers

Created a simple eccentric model for the Sun (very accurate!)Used a deferent and epicycle for the Moon (very accurate!)Could not make models for the remaining planets.



Also created a star catalogue

Observed a nova (new star)

Discovered Precession, the slow motion of the stars over the course of many, many years.

Attributed this to the motion of the stellar sphere (previously thought to be completely motionless)

Precession is real, but has a different mechanism



Aristarchus of Samos

Proposed a heliocentric (sun-centered) cosmos.

Ideas were not well received, only one known follower

Calculated the sizes of the Earth and the Moon, as well as their distances in Earth radii (didn’t know the size of the Earth)

Shortly later – Eratosthenes calculated the size of the Earth, so a value could be plugged in

Hipparchus also calculated the size of the Sun and Moon

Both guys greatly underestimated the distance of the Sun from the Earth. They were fairly close on the Moon though!!




Used shadows and logic to determine that the Moon was closer to the Earth than the Sun.

The Greeks understood that the moon reflected sunlight.

How should that illumination look like from the Earth?

If Moon is further than sun (should be nearly fully lit)

If Moon is much closer than sun (should be ½ lit)

 this is what is true!!!

Estimated the moon’s distance at 40 Earth Radii away (actually 60)

Estimated the Moon to be 1/3

rd the size of Earth’s shadow (actually ¼), this is difficult to measure.To get the solar distance, used the phases of the moon. If the sun were close, there would be a difference in time between the 1


and 3


quarter moons due to angles.

Estimated the distance to Sun to be 20x that of the Earth-Moon distance (actually 390x) Logic was sound though


Ptolemaic Astronomy

The Almagest

Introduced the equant, a new mathematical tool.

Gave a comprehensive treatment of astronomy, which is why it’s one of the few surviving works

Placed the planets in the order that survived until it was replace by the Heliocentric and



systems in the 1600’sMoon, Mercury, Venus, Sun, Mars, Jupiter, Saturn, Fixed StarsGreatly influenced Indian Astronomy


Indian Astronomy

Astronomy and Hinduism (primary religion of India) are tightly interwoven

Had extensive contact with Greek civilization, so heavily influenced by them

Indian Astronomer Aryabhata described motions of planets and eclipses in 600 A.D.

Proposed a Heliocentric (Sun-centered model) of the solar system. Believed that the moon reflected sunlight, and that the Earth moved.


Unfortunately, many early record have been destroyed and lost due to invasion/climate


Arab (Islamic) Astronomy

Mostly a continuation of Greek Astronomy

Many of our records of Greek Astronomy are those saved by the Arabic Cultures

Ptolemy’s work was saved in an Arabic translation called al-


820 A.D. – Measured the circumference of the Earth to within 4% of it’s true value

850 A.D. – al-

Farghani corrected many errors in Ptolemy’s work.

Improved measurements of the Earth’s orbital tilt and the precession of the Earth’s axisAdvanced the field of Optics, and used it to make better observations of the sky, building observatories


Arab (Islamic) Astronomy

Invented the Pinhole camera, used to measure stellar positions

However, they created no new cosmological models because pictorial representations of the heavens are forbidden by the Koran

The prefix ‘al-’ means “the” in Arabic, and it influences many of the names in Astronomy and other fields

Algebra, algorithm, Algol,


, Aldebaran, etc…

Many Arabic manuscripts have not even been read or even catalogued at this time, so there may be more fascinating discoveries they made that we don’t know about.


Egyptian Astronomy

By 3000 B.C.E – Egyptian Astronomers had developed

The 365 day calendar

Alignments of the pyramids to the pole star (



The pole star moves because of Precession – the slow “wobble” of Earth’s axis over a 26,000 year period

Temple of Amun-Re at Karnak was aligned to the rising of the midwinter sun

It no longer is, because of the obliquity of the Earth’s axis (The 23.5 degree tilt is slowly changing over a 41,000 year period)Religious festivals were timed to Astronomical eventsPredicting the flooding of the Nile river.

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