History of AstronomyHistory of Astronomy

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The UniverseThe Universe• TO THE ANCIENTS:

– Bright Stars

– Wandering stars (planets)

– Changes of the seasons

– Every morning the Sun appears

– At times the Moon appears

What are the stars

Where are they located?

Why are they there?

What makes the sun rise?

Where does the Sun go at night?

What role humans have in all this?

How did all this begin?

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MythologyMythology• Universe Models:

– Related to human hopes, desires, and culture.

– Anthropomorphic

– Anthropocentric

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The UniverseThe Universe• TODAY:

– How did the Big Bang Begin and why?

– Is the universe “open” or “closed”?

– What are space and time?

– Why is there an arrow of time?

– What are black holes?

– Are we alone in the universe?

– What is Gravity?

– Is there a TOE (Theory of Everything)?

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Astronomy in Ancient EgyptAstronomy in Ancient Egypt• NABDA PLAYA - ~5000 BC Egyptian Stonehenge• Stellar alignments of Temples such as AMEN-RA• From ancient Egyptian tombsides

– Timekeeping, seasons by the rising of Sirius– Clocks showing nights divided by 12 parts– Shadow clocks, and water clocks

• Stars on tomb ceilings– Tomb of Senmet (1472 BC)

• Orion, Sirius and the planets– Temple of HATHOR at Dendera (700 BC)

• Circular Dendera Zodiac (now in the Louvre)

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Egyptian StonehengeEgyptian StonehengeJuly 1998, Discover MagazineJuly 1998, Discover Magazine

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Temple of DenderaTemple of DenderaCeiling ZodiacCeiling Zodiac

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StonehengeStonehenge

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Babylonian GenesisBabylonian Genesis– Enuma Elish

– Summarians ~3500 BC

– Kassite regime ~1450 BC

• Cosmos began with CHAOS and WATER

• From these, two Gods were created:

– Marduk – protector of Babylon

– Tiamat – sea goddess of chaos

• Marduk killed Tiamat and created the earth from her body

“Marduk bade the moon come forth;

Entrusted night to her,

Made her creature of the dark, to measure time;

And every month, unfailingly, adorned her with a crown.”

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Boundary stone (kudurru)

Kassite dynasty, about 1125-1100 BC Mesopotamia, British Museum

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Greek GenesisGreek Genesis• The cosmos began from the God Chaos, who had children

who created Other Titan Gods.

• Zeus – governed the sky• Poseidon – governed the sea• Athena – the Goddess of wisdom• Apollo – the God of light and music• Aphrodite – the Goddess of beauty and love• Ares – the God of war• Dionysos – the God of wine

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The Geocentric ModelThe Geocentric Model

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Chinese GenesisChinese Genesis• In the beginning the cosmos was a great EGG.• The God Pan Gu slept in the egg. It awoke and

broke free from the egg, the heavy material became the earth, and the light the air.

His breath became the wind

His voice the thunder

His left eye the Sun

His right eye the Moon

“Heaven and earth are large, and in the whole of empty space they are but as a small grain of rice”

(Bo Ya Qin)

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Chinese Star Chart. 940 AD. British Library Dunhuang Collection.

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• The Hebrew Old Testament Genesis– “Let there be light, and there was light”

– God created the universe in six days and rested during the seventh day.

– God created man in his own image.

– God gave free will to man.

• Tanzanian Genesis:– At the beginning there was a tree and ants lived in it.

One day the wind blew away a leaf with some ants. The ants ate the leaf and themselves and grew into a huge ball that became the earth.

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Aztec Mesoamerican GenesisAztec Mesoamerican Genesis• At the beginning when everything was mixed up and

confused (chaos), there was Ometeotl, God of Duality• Ometeotl created himself.• When it pleased Ometeotl, he blew and separated the water

from heaven and the earth.• When everything was darkness, the Gods gathered. They

lit a fire on which the one who would become the Sun would be sacrificed.

• The God Namahuatl jumped into the fire and was consumed. He became the Sun. The God Tecciztecatl jumped after him, but the fire was weaker, and he became the Moon.

• The Milky Way was Tamoanchar “Paradise”, from which the gods and humans had been expelled.

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Native American CosmologiesNative American Cosmologies• Walam Olum

– A chronicle of the Delaware (the Lenni Lenape) Indians

– “There at the edge of the water where the land ends, the fog over the earth was plentiful, and this was where the Great Spirit stayed.

– He created much land here as well as land on the other side of the water. He created the sun and the stars at night. All these he created so they might move.”

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Aristarchus of SamosAristarchus of Samos(310 – 230 BC)(310 – 230 BC)

• The First Heliocentric System• The Moon reflects light from the Sun• Estimates of the distances to the Moon and Sun

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EratosthenesEratosthenes(276 – 195 BC)(276 – 195 BC)

• Head of the famous Alexandria Library• Geographer, astronomer, philosopher• Scientific measurement of the size of the earth

– Assumed that Alexandria and Syene (Aswan) were on the same meridian.

– On the longest day of the year (Summer Solstice) when the sun was at its highest point, he had reports that at Syene there were no shadows ( the sun would shine down deep into a well).

– But at the same time (same day, sun at highest elevation), there were shadows in Alexandria, making an angle of about 1/50 of a circle (~7 degrees)

– Eratosthenes knew the distance between Alexandria and Syene to be about 5000 stades (~500 miles). He deduced a circumference of the earth of 25000 miles (~7 degrees for 500 miles, hence 360 degrees ~25000 miles).

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7°

7°

AlexandriaSyene

To Sun and zenith at Syene

To Sun at noon on June 22

To zenith at Alexandria

Measuring the Measuring the size of the Earthsize of the Earth

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Ptolemy of AlexandriaPtolemy of Alexandria(Around 150 AD)(Around 150 AD)

• Megale Syntaxis

• Almagest

• All of Astronomy– Constellations

– Star catalogue

– Planetary motions

• One of the great books of science in history as important as– Elements by Euclid

– Principia by Newton

– Origin of Species by Darwin

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Epicycles and Deferents

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Hypatia of AlexandriaHypatia of Alexandria• About 3rd century A.D.• Astronomer and Mathematician with contributions

to geometry and the Astrolabe• “Reserve the right to think, for even to think

wrongly is better than not to think at all.”• “To teach superstitions as truth is a most terrible

thing.”

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The AstrolabeThe Astrolabe

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Motion of the MoonMotion of the Moon

Nasir ad-Din at-Tusi, Tadhkira (Memoir on Astronomy). Library of Congress.

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The ZodiacThe Zodiac

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Nicolaus CopernicusNicolaus Copernicus

Portrait from Toruń - beginning of the 16th century.

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Nicolaus CopernicusNicolaus Copernicus

Portrait from the Jan Matejko's painting - end of the 19th century.

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DeDe Revolutionibus Revolutionibus On the Revolution of the Heavenly SpheresOn the Revolution of the Heavenly Spheres

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DeDe Revolutionibus Revolutionibus On the Revolution of the Heavenly SpheresOn the Revolution of the Heavenly Spheres

As described in the text, this is the famous passage in Copernicus’ manuscript for his De Revolutionibus where the section about Aristarchus was crossed out shortly before publication.

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Retrograde motionRetrograde motion

From Dr. Stephen Daunt, University of Tennesee, Knoxville

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Retrograde MotionRetrograde Motion

From Dr. Ted Snow, University of Colorado, Boulder

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Tycho BraheTycho Brahe

Tycho Brahe’s cosmological model. Earth remained at the center of the cosmos, and the Sun circled the Earth, but the other planets orbited the Sun.

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The ObservatoryThe ObservatoryIsland of HvenIsland of Hven

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Galileo GalileiGalileo Galilei

Portrait by Tintoretto

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Galileo’s TelescopesGalileo’s Telescopes

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Sir Isaac NewtonSir Isaac Newton

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Entretiens sur la pluralité des mondesEntretiens sur la pluralité des mondes (Conversations of the Plurality of Worlds)(Conversations of the Plurality of Worlds)

Bernard le Bovier de Fontenelle, 1686Bernard le Bovier de Fontenelle, 1686

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The Solar SystemThe Solar System

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Albert EinsteinAlbert Einstein

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Today’s Big Bang “Myth” of CreationToday’s Big Bang “Myth” of Creation• Some 15 billion years ago the universe was created out of

“nothing” (quantum flucuation), by breaking “Perfect Symmetry” and creating particles out of “fields” and “energy”, and creating forces like gravity.

• This was like a most gigantic fireball explosion that began to expand and cool by creating its own space and time.

• Soon particles formed atoms, which in turn formed huge ensembles that collapsed due to gravity to form galaxies, stars, planets…and you and me.

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Astronomical ChronologyAstronomical Chronology• 5000 BC Egyptian Stonehenge at Nabda Playa

• 3000 BC Stonehenge in Britain (Temple of the Stars)

• 2000 BC Old Babylonian Venus records

• 1450 BC Enuma Elish Babylonian Genesis

• 900 BC Homer’s Iliad and Odyssey describing some of the constellations

• 700 BC Systematic Babylonian records. Zodiac

• 600 BC Greek cosmology

Plato and Aristotle – A spherical earth

Aristarchus of Samos – Heliocentric system

• 200 BC Eratosthenes – the size of the earthApollonius – Planet Epicycles

Hipparchus – Star catalogues, stellar magnitudes, constellations, precession

• 100 AD Ptolemy of Alexandria – The Almagest

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Astronomical ChronologyAstronomical Chronology• 600 – 1400 AD Use of the Astrolabe

Translations from Greek to ArabicTranslations from Arabic to Latin

• 1543 AD N. Copernicus – De Revolutionibus Solar System

• 1576 AD T. Brahe’s Hven Observatory• 1609 AD J. Kepler’s Laws of the Planets• 1610 AD G. Gallilei – The Telescope• 1680 AD I. Newton’s Principia, mathematical physics• 1810 AD Fraunhofer solar spectral lines• 1838 AD First stellar parallax 61 Cygni and Vega• 1916 AD A. Einstein’s new graviation• 1929 AD E. Hubble’s expanding universe

Physical cosmology• 1932 AD K. Jansky – beginning of Radio Astronomy• 1964 AD Big Bang verification – 3K background radiation• 1990 AD Hubble Space Telescope