the origin of modern astronomy 4-1 the roots of astronomy

The Origin of The Origin of Modern Modern

AstronomyAstronomy4-1 4-1

THE ROOTS OF ASTRONOMYTHE ROOTS OF ASTRONOMY

ArchaeoastronomArchaeoastronomyy

Archaeoastronomy is the study of the Archaeoastronomy is the study of the astronomy of ancient culturesastronomy of ancient cultures

Became popular in 1965 when Gerald Became popular in 1965 when Gerald Hawkins published a book called Hawkins published a book called Stonehenge DecodedStonehenge Decoded

http://beyondthebrook.files.wordpress.com/2011/06/stonehenge.jpg


Stonehenge was built in stages Stonehenge was built in stages from about 3000 BC to about from about 3000 BC to about 1800 BC1800 BC

In its first stages it consisted of In its first stages it consisted of a circular ditch slightly larger a circular ditch slightly larger than the length of a football than the length of a football field, with a concentric bank just field, with a concentric bank just inside the ditch and a long inside the ditch and a long avenue leading away toward the avenue leading away toward the northeastnortheast

A massive stone, the Heelstone A massive stone, the Heelstone stands outside the ditch in the stands outside the ditch in the opening of the avenueopening of the avenue

http://arthistoryresources.net/stonehenge/archaeoastronomy.html


In 1740, English scholar W. Stukely In 1740, English scholar W. Stukely suggested that the avenue pointed toward suggested that the avenue pointed toward the rising sun at the summer solsticethe rising sun at the summer solstice

Seen from the center of the monument, the Seen from the center of the monument, the summer-solstice sun rises behind the summer-solstice sun rises behind the HeelstoneHeelstone

Other sight lines point towards the most Other sight lines point towards the most northerly and most southerly risings of the moonnortherly and most southerly risings of the moon

The significance of these alignments has The significance of these alignments has been debated, with some claiming that been debated, with some claiming that Stonehenge was built to predict lunar Stonehenge was built to predict lunar eclipseseclipses

http://www.south24.co.uk/stonehenge.htm

http://www.starteachastronomy.com/pictures/neolithic_stonehenge.jpg

Big Horn Medicine Wheel

http://www.sacredland.org/medicine-wheel/

OTHER MONUMENTS POSSIBLY USED FOR STUDYING

ASTRONOMY

http://wheretowillie.blogspot.com/2011/04/late-afternoon-sun-at-el-caracol.html

Caracol temple built by Mayans

The Astronomy of The Astronomy of Ancient EgyptAncient Egypt

Like many ancient cultures ancient Like many ancient cultures ancient Egyptians looked to the stars and tried Egyptians looked to the stars and tried to make sense of what they sawto make sense of what they saw

Different constellations represented Different constellations represented different gods or goddessesdifferent gods or goddesses

For the first time in recorded history For the first time in recorded history they came up with a calendarthey came up with a calendar

Calendar was set by the flooding of the Calendar was set by the flooding of the Nile River and they knew by tracking the Nile River and they knew by tracking the flooding that roughly one year later it flooding that roughly one year later it would flood againwould flood again

The Astronomy of The Astronomy of Ancient EgyptAncient Egypt

Buildings were designed with an orientation Buildings were designed with an orientation to the zodiac, certain stars/constellationsto the zodiac, certain stars/constellations

Egyptians aligned their pyramids and Egyptians aligned their pyramids and temples toward the northtemples toward the north

They believed their pharaohs would become They believed their pharaohs would become stars in the northern sky after they died stars in the northern sky after they died They studied the stars and knew that certain They studied the stars and knew that certain stars never set (circumpolar constellations) stars never set (circumpolar constellations) They believed that once their king died they They believed that once their king died they would become one of these stars that never would become one of these stars that never setset

Great Pyramid of Great Pyramid of GizaGiza

http://www.astronomy.pomona.edu/archeo/egypt/egypt.html

http://www.world-mysteries.com/mpl_2.htm

The Astronomy of The Astronomy of GreeceGreece

Greek astronomers for the first time in the Greek astronomers for the first time in the study of astronomy tried to understand the study of astronomy tried to understand the universe and kept religion and astrology out universe and kept religion and astrology out of their studiesof their studies

Two philosophers made this work easier to Two philosophers made this work easier to comprehend:comprehend:

Thales stated that the mysteries of the Thales stated that the mysteries of the universe are mysteries because they are universe are mysteries because they are unknown, not because they are unknowableunknown, not because they are unknowable

Pythagoras noticed that many things in nature Pythagoras noticed that many things in nature seem to be governed by geometrical or seem to be governed by geometrical or mathematical relationsmathematical relations

One of first people to talk about Earth being a One of first people to talk about Earth being a spheresphere


Plato argued that the most perfect form Plato argued that the most perfect form was the circle and therefore all motions was the circle and therefore all motions in the heavens should be made up of in the heavens should be made up of combinations of circular motioncombinations of circular motion

Eudoxus (student of Plato) took some of Eudoxus (student of Plato) took some of Plato’s ideas and came up with a Plato’s ideas and came up with a combined system of 27 nested spheres combined system of 27 nested spheres rotating at different rates about different rotating at different rates about different axes with a concept of uniform circular axes with a concept of uniform circular motion to produce a mathematical motion to produce a mathematical description of the motions of the universedescription of the motions of the universe


Aristotle believed in the perfections of the Aristotle believed in the perfections of the heavens and that Earth was corrupt and heavens and that Earth was corrupt and changeable changeable

He believed that Earth was center of the universe He believed that Earth was center of the universe ((geocentricgeocentric))

The moon marked the boundary between the imperfect The moon marked the boundary between the imperfect region of Earth and the perfection of the heavens region of Earth and the perfection of the heavens above the moonabove the moon

Aristarchus was one of the first people to propose Aristarchus was one of the first people to propose a theory that Earth rotated on its axis and a theory that Earth rotated on its axis and revolved around the sunrevolved around the sun

Most of his writings have been lost Most of his writings have been lost

Later astronomers rejected his theory because they Later astronomers rejected his theory because they couldn’t see parallaxcouldn’t see parallax

ParallaxParallax is the apparent change in position of an object is the apparent change in position of an object due to a change in the location of the observerdue to a change in the location of the observer


Hipparchus was the greatest of ancient Hipparchus was the greatest of ancient observersobservers

He proposed that the sun and moon He proposed that the sun and moon traveled around circles with Earth near, traveled around circles with Earth near, but not at, their centers. These off-center but not at, their centers. These off-center circles are now known as circles are now known as eccentricseccentrics

Hipparchus is usually credited with the Hipparchus is usually credited with the invention of trigonometry, he compiled the invention of trigonometry, he compiled the first star catalog, and he discovered first star catalog, and he discovered precessionprecession

http://www.astro.cornell.edu/academics/courses/astro201/hipparchus.htm

The Ptolemaic The Ptolemaic UniverseUniverse

Claudius Ptolemaeus was one of the Claudius Ptolemaeus was one of the great astronomer-mathematicians great astronomer-mathematicians of Ancient Greek timeof Ancient Greek time

He came up with another Earth-He came up with another Earth-centered model centered model

It incorporated the Greek belief that It incorporated the Greek belief that the heavenly bodies move perfectly the heavenly bodies move perfectly with uniform circular motionwith uniform circular motion

Stated that planets sometimes move Stated that planets sometimes move faster and sometimes slower, and faster and sometimes slower, and occasionally they appear to slow to a occasionally they appear to slow to a stop and move backward (retrograde stop and move backward (retrograde motion)motion)

His model stood for almost 1500 His model stood for almost 1500 years.years.

http://www.vikdhillon.staff.shef.ac.uk/teaching/phy105/celsphere/phy105_ptolemy.html



THE COPERNICAN REVOLUTIONTHE COPERNICAN REVOLUTION

Copernicus the Copernicus the RevolutionaryRevolutionary

Nicolaus Copernicus triggered an Earth-Nicolaus Copernicus triggered an Earth-shaking revision in human thought by shaking revision in human thought by proposing that the universe is not centered proposing that the universe is not centered on Earth but is on Earth but is heliocentricheliocentric

He 1He 1stst proposed that the sun was the center proposed that the sun was the center of the universe in 1507, but did so of the universe in 1507, but did so anonymously because of fear of being anonymously because of fear of being charged with heresy charged with heresy

Much of the land was in his life was Much of the land was in his life was controlled by the Roman Catholic Church and controlled by the Roman Catholic Church and their belief was that the Earth was the their belief was that the Earth was the center of the universe center of the universe


In 1543, when he realized In 1543, when he realized he was dying he he was dying he published his book for all published his book for all to readto read

The most important idea The most important idea in the book was the in the book was the placement of the sun at placement of the sun at the center of the universethe center of the universe

He explained retrograde He explained retrograde motion by stating that motion by stating that Earth moves faster along Earth moves faster along its orbit than planets its orbit than planets further from the sun so further from the sun so Earth periodically Earth periodically overtakes and passes overtakes and passes these planets, and they these planets, and they appear to slow and fall appear to slow and fall behindbehind

http://outreach.atnf.csiro.au/education/senior/cosmicengine/renaissanceastro.html


He discovered the sun, moon, and planets He discovered the sun, moon, and planets suffered small variations in their motionssuffered small variations in their motions

These variations could not explain with the concept These variations could not explain with the concept of uniform circular motion centered on the sunof uniform circular motion centered on the sun

Today we recognize those variations as typical of Today we recognize those variations as typical of objects following elliptical orbitsobjects following elliptical orbits

The Copernican The Copernican modelmodel was inaccurate, but the was inaccurate, but the Copernican Copernican hypothesis hypothesis that the universe is that the universe is heliocentric was correctheliocentric was correct

Most astonishing consequence of his hypothesis Most astonishing consequence of his hypothesis was not what it said about the sun, but what it was not what it said about the sun, but what it said about Earthsaid about Earth

By placing the sun at the center, he made Earth By placing the sun at the center, he made Earth move along an orbit just as the other planets didmove along an orbit just as the other planets did

Galileo the Galileo the DefenderDefender

Galileo supported the Galileo supported the Copernican model, but it Copernican model, but it took him time to come took him time to come out and publicly say he out and publicly say he supported it because of supported it because of the criticism he would the criticism he would receive for going against receive for going against the views of the churchthe views of the church

It was the telescope that It was the telescope that drove Galileo to publicly drove Galileo to publicly defend the heliocentric defend the heliocentric modelmodel

http://www.gap-system.org/~history/PictDisplay/Galileo.html


Galileo didn’t invent the telescope Galileo didn’t invent the telescope (created in 1608 by a lens maker in (created in 1608 by a lens maker in Holland), but he was the first person to Holland), but he was the first person to observe the sky systematically and observe the sky systematically and apply his observations to the apply his observations to the theoretical problem of the day – the theoretical problem of the day – the place of the Earthplace of the Earth

http://www.guardian.co.uk/science/blog/2009/aug/25/galileo-telescope-anniversary


What Galileo saw through is telescopes was so What Galileo saw through is telescopes was so amazing he rushed a small book into printamazing he rushed a small book into print and it and it reported a number of major discoveriesreported a number of major discoveries

Reported the moon was not perfect, it had Reported the moon was not perfect, it had mountains and valleys on its surface (Ptolemaic mountains and valleys on its surface (Ptolemaic model said it was perfectmodel said it was perfect

Milky Way was made up of a myriad of stars too Milky Way was made up of a myriad of stars too faint to see with the unaided eyefaint to see with the unaided eye

Revealed four new “planets” circling Jupiter, Revealed four new “planets” circling Jupiter, planets known today as the Galilean moons of planets known today as the Galilean moons of JupiterJupiter

The moons of Jupiter supported the Copernican model The moons of Jupiter supported the Copernican model over the Ptolemaic modelover the Ptolemaic model

Critics said that Earth could not move because the Critics said that Earth could not move because the moon would be left behind, but Jupiter moved yet moon would be left behind, but Jupiter moved yet kept its satelliteskept its satellites

Galileo the Galileo the DefenderDefenderSoon after he published the book he made Soon after he published the book he made

two additional discoveries:two additional discoveries:When he observed the sun, he discovered When he observed the sun, he discovered sunspots, raising the suspicion that the sun sunspots, raising the suspicion that the sun was less than perfect. By noting the was less than perfect. By noting the movements of the spots, he concluded that movements of the spots, he concluded that that the sun is a sphere and that it rotated on that the sun is a sphere and that it rotated on its axisits axis

When he observed Venus, he saw that it was When he observed Venus, he saw that it was going through phases just like the moongoing through phases just like the moon

http://www.jimloy.com/astro/venus.htm

Galileo the DefenderGalileo the DefenderIn 1616, Galileo was asked to stop debating the model of In 1616, Galileo was asked to stop debating the model of the universe and not support the Copernican model by the the universe and not support the Copernican model by the Pope Paul V of the Roman Catholic ChurchPope Paul V of the Roman Catholic Church

In 1623, after the death of 2 popes one of Galileo’s close In 1623, after the death of 2 popes one of Galileo’s close friends became pope and encouraged him to continue his friends became pope and encouraged him to continue his life’s work, but he didn’t revoke the orders from Pope Paul life’s work, but he didn’t revoke the orders from Pope Paul VV

Galileo rushed to complete his next book which was a clear Galileo rushed to complete his next book which was a clear defense of Copernicusdefense of Copernicus

He was then called back to Rome and questioned about his He was then called back to Rome and questioned about his book and was charged and condemned of disobeying the book and was charged and condemned of disobeying the orders given to him in 1616orders given to him in 1616

Although he was sentenced to life imprisonment, he was actually Although he was sentenced to life imprisonment, he was actually confined to his villa for the next 10 yearsconfined to his villa for the next 10 years

Galileo faced the Inquisition because of a conflict between Galileo faced the Inquisition because of a conflict between two ways of knowing and understanding the world. The two ways of knowing and understanding the world. The church taught faith and understanding through revelation, church taught faith and understanding through revelation, but the scientists of the age were inventing a new way to but the scientists of the age were inventing a new way to understand nature that relied on evidence. understand nature that relied on evidence.



THE PUZZLE OF PLANETARY MOTIONTHE PUZZLE OF PLANETARY MOTION

Tycho the Tycho the ObserverObserver

11stst astronomical observations astronomical observations were made in 1563were made in 1563

He observed Jupiter and He observed Jupiter and Saturn nearly merge into a Saturn nearly merge into a single point on August 24single point on August 24thth

This event was tracked to take This event was tracked to take place at another time by the place at another time by the stellar tables of the time, stellar tables of the time, which dismayed him a great which dismayed him a great deal and pushed him further deal and pushed him further into the study of planetary into the study of planetary motionmotion1572 he studied a new star 1572 he studied a new star (now called Tycho’s supernova) (now called Tycho’s supernova) and tried to measure its and tried to measure its parallax, but he saw none and parallax, but he saw none and concluded that it was farther concluded that it was farther away than the moon and was away than the moon and was probably among the stars of probably among the stars of the celestial spherethe celestial sphere

http://www.amblondon.um.dk/en/menu/TheEmbassy/News/Tycho+Brahe+to+be+exhumed.htm

Tycho Brahe’s LegacyTycho Brahe’s LegacyHe made no direct contribution to He made no direct contribution to astronomical theoryastronomical theory

Since he couldn’t measure parallax for the Since he couldn’t measure parallax for the stars he concluded Earth was stationary which stars he concluded Earth was stationary which rejected the Copernican hypothesisrejected the Copernican hypothesis

He also rejected Ptolemaic model because of He also rejected Ptolemaic model because of its inaccurate predictionsits inaccurate predictions

He created his own model in which Earth was He created his own model in which Earth was the immobile center of the universe around the immobile center of the universe around which the sun and moon movedwhich the sun and moon moved

Other planets circled the sunOther planets circled the sun

His bigger contribution was observationalHis bigger contribution was observationalHe didn’t use a telescope because they weren’t He didn’t use a telescope because they weren’t invented yet, but he used instruments to invented yet, but he used instruments to measure angles in the sky with high precisionmeasure angles in the sky with high precision

Kepler the Kepler the AnalystAnalyst

Johannes Kepler was a student of Tycho Johannes Kepler was a student of Tycho BraheBrahe

He studied astronomy with Brahe and He studied astronomy with Brahe and when he died took all of Brahe’s when he died took all of Brahe’s research and started to apply it to the research and started to apply it to the Copernican model, which he believed inCopernican model, which he believed in

https://libwebspace.library.cmu.edu:4430/posner/sp09/subcontents/Kepler.html

Kepler’s Three Kepler’s Three Laws of Planetary Laws of Planetary

MotionMotionHe solved a big problem of the day He solved a big problem of the day which was how did the planets movewhich was how did the planets move

The key to the argument was the ellipseThe key to the argument was the ellipseEllipse is a closed curve enclosing two foci Ellipse is a closed curve enclosing two foci such that the total distance from one focus such that the total distance from one focus to any point on the curve back to the other to any point on the curve back to the other focus equals a constantfocus equals a constant

Another term dealing with ellipses he used Another term dealing with ellipses he used to aid his explanation was eccentricity to aid his explanation was eccentricity (measure of the flattening of an ellipse)(measure of the flattening of an ellipse)

11stst law lawThe orbits of the planets are ellipses The orbits of the planets are ellipses with the sun at one focuswith the sun at one focus

Kepler's First Law is illustrated in the image. The Sun is not at the center of the ellipse, but is instead at one focus (generally there is nothing at the other focus of the ellipse). The planet then follows the ellipse in its orbit, which means that the Earth-Sun distance is constantly changing as the planet goes around its orbit.

22ndnd law lawA line from a planet to the sun sweeps over A line from a planet to the sun sweeps over equal areas in equal intervals of timeequal areas in equal intervals of time

Kepler's second law is illustrated in the figure above. The line joining the Sun and planet sweeps out equal areas in equal times, so the planet moves faster when it is nearer the Sun. Thus, a planet executes elliptical motion with constantly changing angular speed as it moves about its orbit. The point of nearest approach of the planet to the Sun is termed perihelion; the point of greatest separation is termed aphelion. Hence, by Kepler's second law, the planet moves fastest when it is near perihelion and slowest when it is near aphelion.

33rdrd law lawA planet’s orbital period squared is proportional A planet’s orbital period squared is proportional to its average distance from the sun cubedto its average distance from the sun cubed

Kepler's Third Law implies that the period for a planet to orbit the Sun increases rapidly with the radius of its orbit. Thus, we find that Mercury, the innermost planet, takes only 88 days to orbit the Sun but the outermost planet (Neptune) requires about 164 years to do the same

BibliographyBibliographyInformation for Ancient Egypt came Information for Ancient Egypt came from from http://www.spacetoday.org/SolSys/Earth/AncientAstrohttp://www.spacetoday.org/SolSys/Earth/AncientAstronomy.htmlnomy.html

Diagrams and some info for Kepler’s Diagrams and some info for Kepler’s three laws were used from: three laws were used from: http://csep10.phys.utk.edu/astr161/lect/history/keplehttp://csep10.phys.utk.edu/astr161/lect/history/kepler.htmlr.html

the origin of modern astronomy 4-1 the roots of astronomy

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