By Ken Journigan Olympic High Astronomy-Renaissance The History of Astronomy The History of Astronomy

By Ken JourniganBy Ken JourniganOlympic High Astronomy-RenaissanceOlympic High Astronomy-Renaissance

The History of The History of Astronomy Astronomy

Warm UpWarm Up

1.1. What is a geocentric model of the What is a geocentric model of the Universe?Universe?

2.2. According to early astronomers, what did According to early astronomers, what did the Universe consist of ?the Universe consist of ?

3.3. Aristotle said that the cosmos was Aristotle said that the cosmos was composed of five fundamental properties or composed of five fundamental properties or elements. What were they?elements. What were they?

4.4. What did Aristotle think the shape of the What did Aristotle think the shape of the Earth was? Why did he think that?Earth was? Why did he think that?

5.5. Name three things that Hipparchus is Name three things that Hipparchus is known for?known for?

Warm UpWarm Up

1.1. Name two discoveries made by Name two discoveries made by Erastosthenes.Erastosthenes.

2.2. What is an orrary?What is an orrary?

3.3. What is a heliocentric model of the What is a heliocentric model of the Universe?Universe?

4.4. What did Ptolemy include in his model of What did Ptolemy include in his model of the Universe?the Universe?

5.5. What is an epicycle?What is an epicycle?

6.6. How many epicycles did Ptolemy’s model How many epicycles did Ptolemy’s model include to work correctly?include to work correctly?

Warm Up Warm Up

1.1. Who was Tycho Brahe?Who was Tycho Brahe?

2.2. What did Tycho Brahe do?What did Tycho Brahe do?

3.3. Who was Nicholas Copernicus and Who was Nicholas Copernicus and what did he propose?what did he propose?

4.4. Who was Johann Kepler?Who was Johann Kepler?

5.5. Name and define his three laws.Name and define his three laws.

Warm UpWarm Up

1.1. What is Newton’s 1What is Newton’s 1stst law of law of Universal motion?Universal motion?

2.2. What is Newton’s 2What is Newton’s 2ndnd law of law of Universal motion?Universal motion?

3.3. What is Newton’s 3What is Newton’s 3rdrd law of law of Universal motion?Universal motion?

4.4. What is the mathematical formula What is the mathematical formula for gravity?for gravity?

Warm UpWarm Up

1.1. On Planet X, a pendulum swings 50 On Planet X, a pendulum swings 50 times in 60 seconds from a 30 cm times in 60 seconds from a 30 cm string. What is the force of gravity string. What is the force of gravity on Planet X?on Planet X?

2.2. On Planet Y, a pendulum swings On Planet Y, a pendulum swings 120 times in 60 seconds from a 40 120 times in 60 seconds from a 40 cm string. What is the force of cm string. What is the force of gravity on Planet Y?gravity on Planet Y?

Astronomical HistoryAstronomical History

A very complete story of A very complete story of astronomy is told in its astronomy is told in its

history. The men and women history. The men and women of astronomical history are of astronomical history are

synonymous with the synonymous with the historical evolution of this historical evolution of this

observational science.observational science.

Geocentric vs. Geocentric vs. HeliocentricHeliocentric

http://www.astro.utoronto.ca/~zhu/http://www.astro.utoronto.ca/~zhu/ast210/both.htmlast210/both.html

Universal ModelsUniversal Models

TheThe

Geocentric Model Geocentric Model SupportersSupporters

The Geocentric Model of the The Geocentric Model of the UniverseUniverse

With one mere exception (to be With one mere exception (to be named later), ancient astronomers named later), ancient astronomers placed the Earth at the center of the placed the Earth at the center of the known Universe. This Universal known Universe. This Universal Model was known as the Model was known as the Geocentric ModelGeocentric Model. “Geo” meaning . “Geo” meaning Earth and “centric” meaning Earth and “centric” meaning centered.centered.

Aristotle (Aristotle (384 BC – – March 7, , 322 BC) )

Aristotle was an Aristotle was an ancient Greek philosopher, a , a student of student of Plato and teacher of and teacher of Alexander the Great. Aristotle had a strong . Aristotle had a strong influence, and his teachings carried great influence, and his teachings carried great weight. He promoted the geocentric model. weight. He promoted the geocentric model. According to Aristotle the cosmos were According to Aristotle the cosmos were composed of five fundamental properties composed of five fundamental properties

Earth Earth Air Air Water Water Fire Fire The spherical shells of The spherical shells of heavenly bodies with Earth heavenly bodies with Earth at the center at the center

AristotleAristotle

Aristotle believed that everything in the Aristotle believed that everything in the regions outside the Earth was perfect and regions outside the Earth was perfect and eternally unchanging. All objects in the eternally unchanging. All objects in the heavens were supposed to be perfect heavens were supposed to be perfect circles, except for stars, which were circles, except for stars, which were featureless points of light.featureless points of light.

Celestial SphereCelestial Sphere

http://www.mathpages.com/home/http://www.mathpages.com/home/star3.htmstar3.htm

Warm UpWarm Up

1.1. Give three examples of evidence of Give three examples of evidence of early astronomy!early astronomy!

2.2. The Universal model that places Earth The Universal model that places Earth at the center is called what?at the center is called what?

3.3. Aristotle said that the cosmos was Aristotle said that the cosmos was composed of five fundamental composed of five fundamental properties or elements. What were properties or elements. What were they?they?

4.4. What did Aristotle thing the shape of What did Aristotle thing the shape of the Earth was? Why did he think that?the Earth was? Why did he think that?

AristotleAristotleAristotle concluded that the Earth Aristotle concluded that the Earth was round and not flat as some at was round and not flat as some at the time believed. He based this on the time believed. He based this on his observation of lunar ellipses his observation of lunar ellipses where a portion of the Earth’s where a portion of the Earth’s shadow falls on the moon. shadow falls on the moon.

AristotleAristotle

Aristotle’s beliefs about the Aristotle’s beliefs about the geocentric model of the universe geocentric model of the universe would pervade astronomy to such an would pervade astronomy to such an extent, that they would not be extent, that they would not be challenged for another 1500 years.challenged for another 1500 years.

Plato and AristotlePlato and Aristotle

The Greek Astronomer The Greek Astronomer Hipparchus

Hipparcus (c. 190 BCE--c. 120 BCE) was born in Nicaea, a Hipparcus (c. 190 BCE--c. 120 BCE) was born in Nicaea, a city in what is now Turkey. In the year 135 BCE, he was city in what is now Turkey. In the year 135 BCE, he was stargazing and saw a bright point of light he didn't recognize.stargazing and saw a bright point of light he didn't recognize.

This star appeared inThis star appeared in

the constellation Scorpio.the constellation Scorpio.

It turned out to be a It turned out to be a

supernova. This disprovedsupernova. This disproved

Aristotle’s idea of the Aristotle’s idea of the

perfect, unchanging Universeperfect, unchanging Universe


Developed the first catalog of stars Developed the first catalog of stars Developed a magnitude scale Developed a magnitude scale

where 1 represented the brightestwhere 1 represented the brighteststars and 6 represented thestars and 6 represented the

dimmest stars.dimmest stars. Determined the precession Determined the precession

of Earth based on recordsof Earth based on records from the past and compared from the past and compared

it to his own observations it to his own observations


Hipparcus cataloged the locations Hipparcus cataloged the locations and brightness of over 850 stars. In and brightness of over 850 stars. In addition, he calculated the length of addition, he calculated the length of the year to within seconds of its the year to within seconds of its actual value and developed a system actual value and developed a system to predict eclipses to within hours.to predict eclipses to within hours.

Stellar MagnitudeStellar Magnitude

Hipparchus’ invented a system to identify Hipparchus’ invented a system to identify how bright stars are. He placed all the how bright stars are. He placed all the stars he observed on a scale that he stars he observed on a scale that he called “magnitude”. The brightest called “magnitude”. The brightest (magnitude 1) star was Sirius. (magnitude 1) star was Sirius. Magnitude 6 stars were just barely Magnitude 6 stars were just barely visible. Each level of the magnitude scale visible. Each level of the magnitude scale represented a change in brightness of 2.5 represented a change in brightness of 2.5 times. A modified version of this system times. A modified version of this system is still used. Magnitude 1 stars are 100 is still used. Magnitude 1 stars are 100 times brighter than magnitude 6 star.times brighter than magnitude 6 star.

The Greek Astronomer The Greek Astronomer Hipparchus Hipparchus had a problem making his Hipparchus had a problem making his

star chart. It was easy enough to map star chart. It was easy enough to map the surface of the Earth, because the the surface of the Earth, because the Earth has landmarks: rivers, Earth has landmarks: rivers, mountains, cities--places of known mountains, cities--places of known location, to which other places can be location, to which other places can be compared. The sky, however, has no compared. The sky, however, has no landmarks, just the stars themselves. landmarks, just the stars themselves. Hipparchus decided to invent Hipparchus decided to invent "landmarks" of his own. He picked one "landmarks" of his own. He picked one point in the sky and drew imaginary point in the sky and drew imaginary lines radiating out from it, like the lines radiating out from it, like the spokes of a wheel. Then he drew circles spokes of a wheel. Then he drew circles around this central point which grew around this central point which grew larger and larger. larger and larger.


This made a grid around the sky, on which This made a grid around the sky, on which Hipparchus could locate any star he wanted. Hipparchus could locate any star he wanted. This idea soon improved Earthly map-making This idea soon improved Earthly map-making as well: the modern lines of longitude and as well: the modern lines of longitude and latitude come directly from Hipparchus's latitude come directly from Hipparchus's method of mapping the sky. method of mapping the sky.

Instead of locating stars on the "celestial Instead of locating stars on the "celestial sphere" (the entiresphere" (the entire

area visible around the Earth), area visible around the Earth), later map-makers drew later map-makers drew gridlines on their chartsgridlines on their charts of the Earth's sphere. of the Earth's sphere.

EratosthenesEratosthenes

EratosthenesEratosthenesEratosthenes was born Eratosthenes was born in Cyrene, Greece in in Cyrene, Greece in 276 BC (now modern 276 BC (now modern day Libya. Studying in day Libya. Studying in Alexandria and Athenes, Alexandria and Athenes, he was eventually he was eventually appointed as chief appointed as chief librarian of the great librarian of the great Library of Alexandria.Library of Alexandria.It was during this time It was during this time that he built the famous that he built the famous armillary sphere as a armillary sphere as a model of the celestial model of the celestial sphere (until the later sphere (until the later invention of the orrery) invention of the orrery)

OrreryOrrery

Antikythera mechanism Antikythera mechanism Many modern scholars believe that Many modern scholars believe that Eratosthenes was critical in the design on Eratosthenes was critical in the design on the Antikythera mechanism (orrery) due the Antikythera mechanism (orrery) due to his exclusive knowledge concerned the to his exclusive knowledge concerned the Earth’s relationship with the moon. Many Earth’s relationship with the moon. Many consider it the first analog computer. It consider it the first analog computer. It was part of the cargo discovered on a was part of the cargo discovered on a 2,500 year old roman sailing ship.2,500 year old roman sailing ship.

Recreation of the Recreation of the Antikythera mechanismAntikythera mechanism

Eratosthenes and Size of the Eratosthenes and Size of the EarthEarth

About 250 BC, About 250 BC, EratosthenesEratosthenes used some of Aristotle's used some of Aristotle's ideas to calculate the size of the Earth. On the ideas to calculate the size of the Earth. On the summer solstice, observers at Syene, Egypt saw the summer solstice, observers at Syene, Egypt saw the sun directly overhead (the well). He also knew that in sun directly overhead (the well). He also knew that in his hometown ofAlexandria, Egypt that the sun was at his hometown ofAlexandria, Egypt that the sun was at an angle of about 7.5an angle of about 7.500 on that day. The angular on that day. The angular displacement was measured. displacement was measured. Using simple geometry, he calculated the distant from Using simple geometry, he calculated the distant from Syene to Alexandria represented 1/50 of a circle. Syene to Alexandria represented 1/50 of a circle. Hiring someone to walk the distance to measure it Hiring someone to walk the distance to measure it 5,000 stadia, where each stadia equals about 700 m), 5,000 stadia, where each stadia equals about 700 m), he calculated that circumference of the Earth at he calculated that circumference of the Earth at around 252,000 stadia (or about 46,420 km). The around 252,000 stadia (or about 46,420 km). The result was within 1 percent accuracy of the figure result was within 1 percent accuracy of the figure known today. known today.

EratosthenesEratosthenes

Eratosthenes was an athlete, poet, Eratosthenes was an athlete, poet, mathematician and astronomer. In mathematician and astronomer. In addition to figuring our the Earth’s addition to figuring our the Earth’s circumference he also calculated the circumference he also calculated the tilt of the Earth’s axis and invented tilt of the Earth’s axis and invented the leap day. He is likely the the leap day. He is likely the astronomer to first suggest the idea astronomer to first suggest the idea of the epicycle as well.of the epicycle as well.

Warm UpWarm Up1.1. Name three innovative (new) things that Name three innovative (new) things that

Hipparchus did!Hipparchus did!

2.2. According to Hipparchus system to According to Hipparchus system to classify stars, what is the brightest star?classify stars, what is the brightest star?

3.3. According to Hipparchus system to According to Hipparchus system to classify stars, what is the dimmest star?classify stars, what is the dimmest star?

4.4. What was Eratosthenes job in What was Eratosthenes job in Alexandria?Alexandria?

5.5. What is he most famous for?What is he most famous for?

6.6. What is an armillary sphere?What is an armillary sphere?

7.7. What was the Antikythera mechanism?What was the Antikythera mechanism?

PtolemyPtolemy

When I trace at my pleasure the When I trace at my pleasure the windings to and fro of the heavenly windings to and fro of the heavenly bodies, I no longer touch the earth with bodies, I no longer touch the earth with my feet: I stand in the presence of Zeus my feet: I stand in the presence of Zeus himself and take my fill of ambrosia, himself and take my fill of ambrosia, food of the gods.food of the gods.(studying the star sure makes me (studying the star sure makes me happy)happy)

Quoted in C B Boyer, Quoted in C B Boyer, A History of Mathematics A History of Mathematics (New York 1968)(New York 1968)

PtolemyPtolemy

Ptolemy’sPtolemy’s full Latin name was full Latin name was Claudius PtolemaeusClaudius Ptolemaeus (fl. AD 87-150, (fl. AD 87-150, Alexandria), He was an ancient Alexandria), He was an ancient astronomer, geographer, and astronomer, geographer, and mathematician who considered the mathematician who considered the Earth the center of the universe Earth the center of the universe

(the "Ptolemaic system"). (the "Ptolemaic system").

Virtually nothingVirtually nothing

is known about his life.is known about his life.

PtolemyPtolemy

Claudius Ptolemy lived in Rome around Claudius Ptolemy lived in Rome around 100 AD. His model of the solar system and 100 AD. His model of the solar system and heavenly sphere was a refinement of heavenly sphere was a refinement of previous models developed by Greek previous models developed by Greek astronomers. Ptolemy’s major astronomers. Ptolemy’s major contribution, however, was that his model contribution, however, was that his model could so accurately explain the motions of could so accurately explain the motions of heavenly bodies, it became the model for heavenly bodies, it became the model for understanding the structure of the solar understanding the structure of the solar system. Nearly all the early models, system. Nearly all the early models, including Ptolemy’s version of the solar including Ptolemy’s version of the solar system, assumed that the Earth was the system, assumed that the Earth was the center of the Universe.center of the Universe.

The Ptolemaic Model The Ptolemaic Model

The Ptolemaic model accounted for the The Ptolemaic model accounted for the apparent motions of the planets in a apparent motions of the planets in a very direct way, by assuming that each very direct way, by assuming that each planet moved on a small sphere or planet moved on a small sphere or circle, called an epicycle, that moved on circle, called an epicycle, that moved on a larger sphere or circle, called a a larger sphere or circle, called a deferent. The stars, it was assumed, deferent. The stars, it was assumed, moved on a celestial sphere around the moved on a celestial sphere around the outside of the planetary spheres.outside of the planetary spheres.

The EpicycleThe Epicycle

http://physics.syr.edu/courses/java/demos/kennett/Epicycle/Epicycle.html

The idea of the epicycle was The idea of the epicycle was incorporating into Ptolemy’s incorporating into Ptolemy’s universal model in order to explain universal model in order to explain retrograde motionretrograde motion

Prograde Versus Prograde Versus Retrograde MotionRetrograde Motion

Prograde Motion: The regular west Prograde Motion: The regular west to east migration of celestial bodies to east migration of celestial bodies across the sky.across the sky.

Retrograde Motion: The irregular Retrograde Motion: The irregular and periodic transit of planets across and periodic transit of planets across the sky from east to west.the sky from east to west.

Prograde Versus Prograde Versus Retrograde MotionRetrograde Motion

http://jove.geol.niu.edu/faculty/http://jove.geol.niu.edu/faculty/stoddard/JAVA/luminaries.htmlstoddard/JAVA/luminaries.html

The Ptolemaic ModelThe Ptolemaic Model

To accurately predict the motions of To accurately predict the motions of the heavens, Ptolemy used 80 the heavens, Ptolemy used 80 epicycles to construct his model. epicycles to construct his model. The model was very accurate in The model was very accurate in predicting the motions of the predicting the motions of the heavens and therefore survived for heavens and therefore survived for around 1,400 years! Imagine what around 1,400 years! Imagine what wrong ideas are around now that wrong ideas are around now that will last for that long!will last for that long!

Universal ModelsUniversal Models

TheThe

Heliocentric Model Heliocentric Model SupportersSupporters

The Heliocentric ModelThe Heliocentric Model HeliocentricHeliocentric (sun-centered) model (sun-centered) model

More accurately accounted for all More accurately accounted for all observations of the movement of the sun observations of the movement of the sun and the moon, and the planets, and the and the moon, and the planets, and the stars stars

were good predictors of future positions were good predictors of future positions of celestial bodies; models were verifiable of celestial bodies; models were verifiable

simplicity (Occam's Razor or the simplicity (Occam's Razor or the Principle of Parsimony) - as few Principle of Parsimony) - as few assumptions or rules as possible; no assumptions or rules as possible; no contradictions. contradictions.

Heliocentric ModelHeliocentric Model

Aristarchus of SamosAristarchus of Samos, a Greek , a Greek about 310-230 BC, had a about 310-230 BC, had a heliocentric model. He proposed heliocentric model. He proposed that all of the planets, including that all of the planets, including Earth revolved around the Sun, Earth revolved around the Sun, and that the Earth rotates on its and that the Earth rotates on its axis once a day. His ideas did axis once a day. His ideas did not gain widespread acceptance not gain widespread acceptance during his lifetime.during his lifetime.

Aristarchus of SamosAristarchus of SamosAristarchus was the first person to Aristarchus was the first person to give the solar system scale.give the solar system scale.

Nicholaus Copernicus/Mikolaj Nicholaus Copernicus/Mikolaj KopernikKopernik

Nicholaus CopernicusNicholaus Copernicus

Born in Trum, Poland, Copernicus was Born in Trum, Poland, Copernicus was the youngest of four children. His the youngest of four children. His father was a well to do merchant father was a well to do merchant (copper trader), politician and civic (copper trader), politician and civic leader.leader.

Following college and his fathers death, Following college and his fathers death, Copernicus went to live with his uncle Copernicus went to live with his uncle who nominated him for a position as who nominated him for a position as canon (a church official with a good canon (a church official with a good salary and no work). salary and no work).

Nicholaus Copernicus and the Nicholaus Copernicus and the Revival of the Heliocentric Revival of the Heliocentric

Universe.Universe.Copernicus Copernicus was was dissatisfied with the dissatisfied with the complexity of the complexity of the geocentric model. In 1514 geocentric model. In 1514 he anonymously he anonymously published a hand-written published a hand-written document called the document called the ““Little Commentary”Little Commentary” where he espoused and where he espoused and supported the idea of a supported the idea of a heliocentric Universe. heliocentric Universe. His beliefs would His beliefs would ultimately get him in ultimately get him in trouble with the Church. trouble with the Church.


Universe.Universe. His ideas included:His ideas included:

Sun is at the center of the universe, motionless; Sun is at the center of the universe, motionless; stars are motionless around the edge stars are motionless around the edge

Planets all revolve around the sun (6 total Planets all revolve around the sun (6 total including Earth) including Earth)

Moon revolves around Earth Moon revolves around Earth Earth rotates on axis causing apparent daily Earth rotates on axis causing apparent daily

motion of the heavens motion of the heavens Earth revolves around sun causing sun's annual Earth revolves around sun causing sun's annual

movements movements Retrograde motion of planets is due to relative Retrograde motion of planets is due to relative

planetary motions planetary motions Planetary orbits are perfect circles Planetary orbits are perfect circles


Universe.Universe.Copernicus was the first to Copernicus was the first to accurately determine the relative accurately determine the relative distances of the planets from the distances of the planets from the sun. sun.

Planetary Distances Planetary Distances According to CopernicusAccording to Copernicus

PlanetPlanet Copernican DistanceCopernican Distance Real DistanceReal DistanceMercuryMercury 0.38 AU0.38 AU 0.39 AU0.39 AUVenusVenus 0.75 AU0.75 AU 0.72 AU0.72 AUEarthEarth 1.00 AU1.00 AU 1.00 AU1.00 AUMarsMars 1.52 AU1.52 AU 1.52 AU1.52 AUJupiterJupiter 5.22 AU5.22 AU 5.20 AU5.20 AUSaturnSaturn 9.17 AU9.17 AU 9.54 AU9.54 AU

Copernican views marked the beginning of Copernican views marked the beginning of the modern era of astronomy.the modern era of astronomy.

ErrorsErrors

The errors in Copernicus’ The errors in Copernicus’ calculations was due to his calculations was due to his insistence that the planets insistence that the planets maintained circular orbits. As a maintained circular orbits. As a result he had to resort to the use of result he had to resort to the use of epicycles to account for the epicycles to account for the discrepancies of his model. Two discrepancies of his model. Two steps forward and one step back.steps forward and one step back.

Tycho BraheTycho Brahe


Tycho Brahe was born in Denmark Tycho Brahe was born in Denmark (now Sweden) in 1546 to a wealthy, (now Sweden) in 1546 to a wealthy, noble family. At age 2 he was noble family. At age 2 he was relinquished to his uncle Jorge by relinquished to his uncle Jorge by agreement. Jorge and his wife were agreement. Jorge and his wife were barren. Jorges Brahe died in 1565 barren. Jorges Brahe died in 1565 from pneumonia after saving King from pneumonia after saving King Fredrik II of Denmark from Fredrik II of Denmark from drowning. drowning.


Around Christmas of 1566, while Around Christmas of 1566, while still a student, Brahe became still a student, Brahe became involved in a drunken argument with involved in a drunken argument with a fellow noble. The argument was a fellow noble. The argument was settled in the dark with rapiers. As a settled in the dark with rapiers. As a result, Brahe was relieved of most of result, Brahe was relieved of most of the upper part of his nose. For the the upper part of his nose. For the rest of his life he wore a copper rest of his life he wore a copper prosthetic glued to his face. prosthetic glued to his face.


Tycho, who received his full inheritance from Tycho, who received his full inheritance from his uncle Jorge plus his fathers full inheritance his uncle Jorge plus his fathers full inheritance in 1571, was a very wealthy man. It is in 1571, was a very wealthy man. It is estimated that at one time Brahe controlled estimated that at one time Brahe controlled one percent of the wealth of Denmark.one percent of the wealth of Denmark.

Being rich and eccentric, Tycho employed a Being rich and eccentric, Tycho employed a dwarf that he believed to be clairvoyant and dwarf that he believed to be clairvoyant and owned an elk that he tamed. Unfortunately owned an elk that he tamed. Unfortunately the elk died according to Brahe from the elk died according to Brahe from “ingesting too much beer and plummeting “ingesting too much beer and plummeting down a flight of stairs” at a party.down a flight of stairs” at a party.


Tycho Brahe Tycho Brahe

benefited greatly from King benefited greatly from King

Fredrik's generous support.Fredrik's generous support.

Brahe received an islandBrahe received an island

called Hven from the king.called Hven from the king.

He turned this island intoHe turned this island into

his own little country. his own little country.


Brahe built a castle on Hven and namedBrahe built a castle on Hven and named

it Uraniborg after Urania, the goddess of the it Uraniborg after Urania, the goddess of the sky. He also built an observatory on the island. sky. He also built an observatory on the island. For over 20 years, Brahe used the island as his For over 20 years, Brahe used the island as his base from which to make astronomical base from which to make astronomical observations. In 1597, Tycho Brahe lost the observations. In 1597, Tycho Brahe lost the Danish king's support, so he went to Danish king's support, so he went to Wandsbech in Germany. He eventually settled Wandsbech in Germany. He eventually settled in Prague where he continued his astronomical in Prague where he continued his astronomical observations. Prague was the capital of the observations. Prague was the capital of the Catholic Church.Catholic Church.


Over a 20 year period of time, Tycho Over a 20 year period of time, Tycho Brahe made consistent observations Brahe made consistent observations which supported the heliocentric which supported the heliocentric theory proposed earlier by Copernicus. theory proposed earlier by Copernicus. These observations were made using These observations were made using only a compass andonly a compass and

a sextant.a sextant.

Brahe catalogued Brahe catalogued

over 1000 stars. over 1000 stars.

Death of BraheDeath of Brahe

Astronomer Johannes Kepler suggested Astronomer Johannes Kepler suggested that Brahe died (1601) of a ruptured that Brahe died (1601) of a ruptured bladder. It was bad manners to leave a bladder. It was bad manners to leave a party before the end in those days. party before the end in those days.

Modern science however has Modern science however has determined that Brahe most likely died determined that Brahe most likely died of mercury poisoning. Some even of mercury poisoning. Some even suggest that he was murdered by Kepler suggest that he was murdered by Kepler for the data that he had collected?!for the data that he had collected?!

Johannes Keplar (12/1571-Johannes Keplar (12/1571-11/1630)11/1630)

Johannes Keplar KeplarJohannes Keplar Keplar

My aim is to say that the machinery of My aim is to say that the machinery of the heavens is not like a divine animal the heavens is not like a divine animal but like a clock (and anyone who believes but like a clock (and anyone who believes a clock has a soul gives the work the a clock has a soul gives the work the honor due to its maker) and that in it honor due to its maker) and that in it almost all the variety of motions is from almost all the variety of motions is from one very simple magnetic force acting on one very simple magnetic force acting on bodies, as in the clock all motions are bodies, as in the clock all motions are from a very simple weight.from a very simple weight.

Johannes Keplar (12/1571-Johannes Keplar (12/1571-11/1630)11/1630)

Born in present-day Germany.Born in present-day Germany. Pursued priesthood, but Pursued priesthood, but

finally decided to teach math.finally decided to teach math. Learned of the CopernicanLearned of the Copernican

model in advanced astronomy.model in advanced astronomy. Excommunicated in 1612.Excommunicated in 1612. Coined the term “satellite”.Coined the term “satellite”.

Johannes Keplar KeplarJohannes Keplar Keplar

Sent copies of some of his work to Tycho Sent copies of some of his work to Tycho Brahe.Brahe.

Tycho Brahe wrote to Kepler’s teacher that Tycho Brahe wrote to Kepler’s teacher that he needed a mathematical assistant and he needed a mathematical assistant and hired Kepler.hired Kepler.

Completed his work on the orbit of Mars in Completed his work on the orbit of Mars in 1605.1605.

Created Created infinitesimal calculusinfinitesimal calculus after after watching tradesmen measure the volume of watching tradesmen measure the volume of wine in barrels at a wedding.wine in barrels at a wedding.

Kepler's LawsKepler's Laws The orbit of each planet is an The orbit of each planet is an ellipse

with the sun at one focus.with the sun at one focus. The square of the period of revolution of The square of the period of revolution of

a planet about the sun is proportional to a planet about the sun is proportional to the cube of the semi-major axis of the the cube of the semi-major axis of the planet’s elliptical orbit.planet’s elliptical orbit.

These laws are illustrated in the These laws are illustrated in the following diagram:following diagram:

Creating an EllipseCreating an Ellipse

1.1. Chose two students to Chose two students to represent the ellipse’s foci.represent the ellipse’s foci.

2.2. Chose one student to represent the Chose one student to represent the orbiting bodyorbiting body

3.3. Chose one student to mark the path Chose one student to mark the path of the orbiting body.of the orbiting body.

http://www.astro.utoronto.ca/~zhu/http://www.astro.utoronto.ca/~zhu/ast210/kepler.htmlast210/kepler.html

Kepler's First LawKepler's First Law

The orbit of each planet is an The orbit of each planet is an ellipse with the sun at one focus.with the sun at one focus.

Kepler's Second LawKepler's Second Law

The line segment joining a planet to The line segment joining a planet to the sun sweeps out equal areas in the sun sweeps out equal areas in equal time intervals. .

http://www.walter-fendt.de/ph11e/keplerlaw2.htm

Kepler's Third LawKepler's Third Law

The square of the period of The square of the period of revolution of a planet about the sun revolution of a planet about the sun is proportional to the cube of the is proportional to the cube of the semi-major axis of the planet’s semi-major axis of the planet’s elliptical orbit.elliptical orbit.

Kepler's Third Law Kepler's Third Law (cont’d)(cont’d)

The square of the period of revolution The square of the period of revolution of a planet about the sun is of a planet about the sun is proportional to the cube of the proportional to the cube of the semi-major axis of the planet’s semi-major axis of the planet’s elliptical orbit. Pelliptical orbit. P22 = A = A3 3 where “P” is where “P” is the orbital period (AU) and “A” is the orbital period (AU) and “A” is the area inscribed by the semi-the area inscribed by the semi-major axis.major axis.

Kepler's LawsKepler's Laws Kepler provided us with a tool, accurate Kepler provided us with a tool, accurate

even by today’s standards, to understand even by today’s standards, to understand the mechanical universe and the orbital the mechanical universe and the orbital nature of the planets.nature of the planets.

The only remaining question, was The only remaining question, was why did why did the planets move the way they didthe planets move the way they did??

The answer to that question could be The answer to that question could be provided by only one man; arguably the provided by only one man; arguably the greatest scientist the world has ever greatest scientist the world has ever seen…….seen…….

Sir Isaac NewtonSir Isaac Newton

Warm UpWarm Up

1.) State Johannes Kepler’s 3 Laws of Planetary 1.) State Johannes Kepler’s 3 Laws of Planetary Motion.Motion.

2.) Explain what each one means (so that even 2.) Explain what each one means (so that even I can understand it). Define any variables I can understand it). Define any variables that you might use!that you might use!

3.) Observations of 3.) Observations of what what planet lead to Kepler’s planet lead to Kepler’s understanding of planetary motion?understanding of planetary motion?

4.) How do you form an ellipse? What are foci? 4.) How do you form an ellipse? What are foci? What is a semi-major axis? What is a semi-major axis?

5.) What was the one question that Kepler 5.) What was the one question that Kepler could not answer?could not answer?

……But first, what about But first, what about Galileo?Galileo?

Galileo GalileiGalileo Galilei

1564 - 16421564 - 1642

Galileo GalileiGalileo Galilei Spent his childhood in Pisa, ItalySpent his childhood in Pisa, Italy Family wanted him to be a Family wanted him to be a

doctor.doctor. Left the University of Pisa inLeft the University of Pisa in

1585 without his degree.1585 without his degree. Saw “Kepler’s” supernova in Saw “Kepler’s” supernova in

1604 while teaching math at1604 while teaching math atthe University at Padua (Venice).the University at Padua (Venice).

Galileo GalileiGalileo Galilei Formulated “Laws of Motion” from Formulated “Laws of Motion” from

observations and experimentation observations and experimentation with pendulums and inclined planes.with pendulums and inclined planes.

Learned of the “Learned of the “perspicillum” perspicillum”

in 1609. in 1609. Created his own telescope and Created his own telescope and

improved on the design by teachingimproved on the design by teaching

himself how to grind lenses .himself how to grind lenses .

Insert: The Early Insert: The Early TelescopeTelescope

teletele = 'far' and = 'far' and skopeinskopein = 'to look or see' = 'to look or see' Invented by Dutch spectacle makerInvented by Dutch spectacle maker

Hans Lippershey in the 1590’s.Hans Lippershey in the 1590’s. Lippershey is the only person to Lippershey is the only person to

apply for a patent for the apply for a patent for the telescope.telescope.

First paper published about use ofFirst paper published about use oftelescope for observation was by telescope for observation was by Englishman Thomas HarriottEnglishman Thomas Harriott

Galileo GalileiGalileo Galilei Sold the rights to the telescope to Sold the rights to the telescope to

the Venetian Senate the Venetian Senate

for a better position.for a better position. Laughed because he Laughed because he

did not own them. did not own them. Began nighttimeBegan nighttime

observations in 1609.observations in 1609.

Galileo GalileiGalileo Galilei

His observations included:His observations included: Mountains on the Moon.Mountains on the Moon. The Galilean moons of Jupiter.The Galilean moons of Jupiter. The phases of Venus.The phases of Venus. Saturn and its rings (though he did Saturn and its rings (though he did

not understand why they periodicallynot understand why they periodicallydisappeared).disappeared).

Sunspots.Sunspots.

Galileo GalileiGalileo Galilei Convicted of heresy, Galileo was placed under Convicted of heresy, Galileo was placed under

house arrest for the remainder of his life, a house arrest for the remainder of his life, a gentle punishment for any individual gentle punishment for any individual convicted during the Inquisition. convicted during the Inquisition.

On 31 October 1992, 350 years after Galileo's On 31 October 1992, 350 years after Galileo's death, Pope John Paul II gave an address on death, Pope John Paul II gave an address on behalf of the Catholic Church in which he behalf of the Catholic Church in which he admitted that errors had been made by the admitted that errors had been made by the theological advisors in the case of Galileo. theological advisors in the case of Galileo. The Church however never admitted that they The Church however never admitted that they were wrong in declaring Galileo a heretic!were wrong in declaring Galileo a heretic!

Sir Isaac Newton (1642-Sir Isaac Newton (1642-1727)1727)


Born in Woolsthorpe, Lincolnshire, Born in Woolsthorpe, Lincolnshire, England on Christmas Day. He was England on Christmas Day. He was quite premature and not expected to quite premature and not expected to live. (His mother said that when he live. (His mother said that when he was an infant, that she could fit him was an infant, that she could fit him inside a one quart pot).inside a one quart pot).

Newton’s father died a few Newton’s father died a few

months before his birth.months before his birth.


His mother remarried to a wealthy His mother remarried to a wealthy clergyman, left home, leaving Isaac to be clergyman, left home, leaving Isaac to be raised by his grandmotherraised by his grandmother

Eight years later, she returned, with three Eight years later, she returned, with three more children and another dead husband. more children and another dead husband. (She’s not having much luck with her (She’s not having much luck with her husbands, is she?).husbands, is she?).

Two years later, Newton went away to Two years later, Newton went away to Grammar School in Grantham, where he Grammar School in Grantham, where he lodged with the local apothecary, and learned lodged with the local apothecary, and learned his fascinated of chemicals. his fascinated of chemicals.


In 1661, his uncle convinced his In 1661, his uncle convinced his mother to send Newton to Trinity mother to send Newton to Trinity College, Cambridge.College, Cambridge.

He supported himself by working in a He supported himself by working in a tavern and cleaning for other faculty tavern and cleaning for other faculty and wealthy students.and wealthy students.

In the summer of 1665, the Black In the summer of 1665, the Black Plague came to Cambridge and Trinity Plague came to Cambridge and Trinity College closed its doors.College closed its doors.

Newton returned home to Woolsthorpe.Newton returned home to Woolsthorpe.


The two years between leaving and The two years between leaving and returning to Cambridge, mark Newton’s returning to Cambridge, mark Newton’s most remarkable and productive years.most remarkable and productive years.

During this time he formulated his ideas During this time he formulated his ideas on moving bodies, gravity and light.on moving bodies, gravity and light.

He also invented integral, differential andHe also invented integral, differential and

infinite series calculus during this time.infinite series calculus during this time. In 1667, began his work in alchemy In 1667, began his work in alchemy

(explain).(explain).


Newton disliked publishing his work Newton disliked publishing his work and usually did so in response to and usually did so in response to other published articles.other published articles.

He was frequently embroiled in He was frequently embroiled in debates over the originality of his debates over the originality of his work.work.

He was haphazard regarding the care He was haphazard regarding the care of his work and frequentlyof his work and frequently

lost and misplaced things.lost and misplaced things.

Sir Isaac NewtonSir Isaac Newton Newton’s first major publication Newton’s first major publication

regarded his invention, design and regarded his invention, design and construction of the first reflecting construction of the first reflecting (or Newtonian) telescope.(or Newtonian) telescope.

Eliminated chromatic aberration.Eliminated chromatic aberration.


Newton elected to the Royal Society.Newton elected to the Royal Society. Through the 1670, Newton became Through the 1670, Newton became

obsessed with theology and alchemy. obsessed with theology and alchemy. He deeply desired to understand He deeply desired to understand the nature of matter. He also tried the nature of matter. He also tried to calculate to age of the Earth using to calculate to age of the Earth using biblical texts. To do this he taught biblical texts. To do this he taught himself Hebrew.himself Hebrew.

Sir Isaac NewtonSir Isaac Newton In 1684, three members of the Royal Society, In 1684, three members of the Royal Society,

Sir Christopher Wren, Robert Hooke and Sir Christopher Wren, Robert Hooke and Edmond Halley, argued as to whether the Edmond Halley, argued as to whether the elliptical orbits of the planets could result elliptical orbits of the planets could result from a gravitational force towards the sun from a gravitational force towards the sun proportional to the inverse square of the proportional to the inverse square of the distance. Halley writes: distance. Halley writes:

Mr. Hook said he had had it, but that he Mr. Hook said he had had it, but that he would conceal it for some time so that others, would conceal it for some time so that others, triing and failing might know how to value it, triing and failing might know how to value it, when he should make it publick.when he should make it publick. (Yea, right!!! What a load!)(Yea, right!!! What a load!)

Sir Isaac Newton and Edmond Sir Isaac Newton and Edmond HalleyHalley

Having heard the rumor that Newton Having heard the rumor that Newton already had the solution they sought, already had the solution they sought, Edmond Halley (namesake of the Edmond Halley (namesake of the comet) visited the mathematician. comet) visited the mathematician.

Newton replied that he had the proof Newton replied that he had the proof from fours years earlier, but sought in from fours years earlier, but sought in vain to find it.vain to find it.

Newton devoted the next three Newton devoted the next three months to reproducing the proof.months to reproducing the proof.

Sir Isaac NewtonSir Isaac Newton Published the Published the PrincipiaPrincipia in 1686, widely in 1686, widely

regarded as the greatest scientific work regarded as the greatest scientific work ever published.ever published.

Publication made Newton a very public Publication made Newton a very public figure which he quickly grew accustomed figure which he quickly grew accustomed to.to.

He was appointed Master of the Mint and He was appointed Master of the Mint and moved from Cambridge to London. He moved from Cambridge to London. He was responsible for many improvements was responsible for many improvements to currency to control “shaving” and to currency to control “shaving” and counterfeiting (ridges, like quarters today. counterfeiting (ridges, like quarters today.

The Ideas of Isaac The Ideas of Isaac NewtonNewton

The central topic of the The central topic of the PrincipiaPrincipia was was gravitational force. Defined by Newton as:gravitational force. Defined by Newton as:

Fg = G (MFg = G (M11) (M) (M22)/ r)/ r2 2 where: (the inverse where: (the inverse square law)square law)

Fg = The force of gravityFg = The force of gravityG = The gravitational constantG = The gravitational constantM1 = The mass of body oneM1 = The mass of body oneM2 = The mass of body twoM2 = The mass of body twor = the distance between the centers of the two r = the distance between the centers of the two

bodiesbodies

Sir Isaac NewtonSir Isaac Newton Orbital flight was explained by Orbital flight was explained by

Newton in a though activity called Newton in a though activity called the “mountain cannon”.the “mountain cannon”.Is seeks to show how an object may Is seeks to show how an object may continually fall and still never his the continually fall and still never his the ground of a round body.ground of a round body.

http://galileoandeinstein.physics.virginia.edu/more_stuff/Applets/newt/newtmtn.html

Newton’s First Law of Newton’s First Law of MotionMotion

Newton’s First Law of Motion Newton’s First Law of Motion states that:states that:

F = ma F = ma where:where:

F = forceF = force

m = massm = mass

a = accelerationa = acceleration

Newton’s Second Law of Newton’s Second Law of MotionMotion

Newton’s Second Law of Motion is Newton’s Second Law of Motion is the Law of Inertia which states that:the Law of Inertia which states that:

A body in motion tends to stay in A body in motion tends to stay in motion (in a straight line) and a body motion (in a straight line) and a body at rest tends to stay at rest, unless at rest tends to stay at rest, unless acted upon by some external force.acted upon by some external force.Mass resists change and the Mass resists change and the natural state of matter is to be in natural state of matter is to be in motion!motion!

Newton’s Third Law of Newton’s Third Law of MotionMotion

Newton’s Third Law of Motion Newton’s Third Law of Motion states:states:

For every action there is an equal, For every action there is an equal, but opposite, reaction.but opposite, reaction.

Or, if I push you, then you push me Or, if I push you, then you push me andand

if you push me then I push you!if you push me then I push you!

Isaac NewtonIsaac Newton

Creator of:Creator of: Reflecting telescopeReflecting telescope Laws of MotionLaws of Motion Laws of GravityLaws of Gravity CalculusCalculus AstrophysicsAstrophysics Our understanding of the true nature Our understanding of the true nature

of lightof light(Not a bad resume, eh?)(Not a bad resume, eh?)

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By Ken Journigan Olympic High Astronomy-Renaissance The History of Astronomy The History of Astronomy