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Earth Space Standard – History 3
5) Understand and be able to explain to students the key figures in the Copernican
Revolution who proved the heliocentric model to be correct.
This final section on history is taught in class with a keen emphasis on the historical
context. We will spend time sharing the story of Martin Luther and the Protestant
Reformation. Martin Luther, although not part of the Astronomy Revolution, opened the
door to challenge the institution called the Roman Catholic Church. One man’s stand
encouraged others to do the same, and in the space of 20 years, the world was turned
upside down. My purpose for integrating history is because Astronomy is such a big part
of the dawn of Enlightenment. This is an opportunity to integrate courses within the
school, for the history teacher can come into the Astronomy classroom, and the
Astronomy teacher can enter into the History classroom. One of the most important goals
of mine at this time is to encourage students that they can do amazing things, even
through they themselves might not appear amazing by today’s definition. Martin Luther
and Nicholas Copernicus were ordinary people who dared to think in an extra ordinary
manner. Each man challenged the institutional belief, encourage careful examination of
evidence, and pushed people to make their own conclusion instead of blindly accepting
what authority teaches.
The Copernican Revolution
The 16th Century was a time of tremendous upheaval for it marked major changes in the
world of scientific and religious thinking. Martin Luther led the Protestant Reformation
with his 95 theses and the Diet of Wurms defense of this thinking in 1517 and 1519.
Since this event marks the opening of the door to scientific thinking as well as a split
from the Church by a large number of people, you are now asked to learn more about the
details of Martin Luther's life and how his writings affected the people as much as did the
writings of Copernicus, Galileo, and Newton. If you have not already done so, please
click on Martin Luther to learn about the Reformation and how the writings of Luther
may have spurred Copernicus to share his new ideas of the solar system with the general
public.
Nicolaus Copernicus - the first real challenge to the Ptolemaic theory
came in 1543, with the publication of a book by Polish churchman
Mikolaj Kopernik, better known by his Latinized name of Nicolaus
Copernicus. His main objection to the geocentric, or earth-centered,
theory was its clumsiness. He recognized that many of the
complications could be removed by putting the sun in the central
place of the system and allowing everything to revolve around it. In
this he was correct, but he was still convinced that all celestial orbits must be perfectly
circular, and he was even reduced to bringing back epicycles. To see a nice set of images
and text regarding the proposed heliocentric model of Copernicus, click on his image at
the left. To learn more details about his life, click on Copernicus and go to his
biographical account. I apologize that some of the weblinks in the biography no longer
operate, but the site is still worth the visit. Within this course, I have highlighted the
heliocentric model and will propose my ideas about the importance of his great
intellectual leap upon all of science and mankind ever since.
Nicolaus Copernicus accomplished much in his
thinking of the motions of the planets, more so
than he expected. At the left is his ideas of how
planets revolved around the sun. He worked out a
detailed theory of the moon in orbit and set the
distance of the moon at about 60 times the earth's
radius - a figure close to what we use today.
He noted that the moon's orbit was not an earthcentered
circle.
He concluded that the earth was definitely a
planet.
Whereas Ptolemy argued against the idea of a
rotating earth because the mountains would be
ripped from their roots, Copernicus argued more
forcefully that such a rotation would have an even great effect on the sky which has a
larger radius. Since neither happened, why not at least look at the earth's rotation as
causing
the
sun
to
appear
to
orbit
the
earth.
Copernicus was the first to recognize that Polaris does not stay in the same position
because
the
axis
of
the
earth
slowly
wobbles.
He justified his conclusions: "... in the midst of all stands the sun. For who could in this
most beautiful temple place this lamp in another or better place than that from which it
can at the same time illuminate the whole? Which some not unsuitably call the light of
the world, others the soul or ruler. Trismegistus calls it the visible God, the Electra of
Sophocles, the all-seeing. So indeed does the sun, sitting on the royal throne, steer the
revolving family of stars." By no means did Copernicus desire to remove God from the
Universe. To him, God could more accurately occupy the central place in creation, with
man revolving around God. The Sun would be the embodiment of the eternal, allpowerful,
and
light
and
life-giving
God.
Essentially, Copernicus desired to bring about a harmony of the natural world, created by
God, and the spiritual world, described by God in the Bible. Furthermore, as seen to the
left, God created everything with perfection, and thus all orbital paths were perfect
circles, even as they were in the drawings of Ptolemy.
Copernicus was well aware that his ideas would offend
the Church; to regard the Earth as anything but supreme
would be to invite a charge of heresy. Prudently, he
withheld publication of his book until he was dying in
1543, even though he developed his theory in 1507. His
little book was entitled "de Revolutionibus" and the cover
page appears to the right of this text.
It has always be difficult for my students to grasp the
importance of Copernicus' work as well as his personal
struggle with sharing his ideas with the public. One needs
only look at the history of the Church to see the origins of
this struggle. Nicolaus Copernicus was a devout Catholic.
To pronounce a heliocentric model would most certainly
mean his excommunication, and the prospect of eternal
death and damnation were a chance he refused to take. For
almost 1400 years, the European world had accepted the geocentric model of Ptolemy.
As mentioned earlier in the history discussion, this model satisfied the observations of
people, their personal philosophy of self-centeredness, the religious convictions as
espoused in the Judeo-Christian Bible, as well as the sheer complexity of the mathematics
and epicycle motions.
Copernicus reasoned that all of the motions that he observed in the sky could be
accounted for with a sun-centered system, and without the necessity of complicated
epicycle motions. He realized, however, that his views would stir up controversy and
perhaps mean trouble for him from the Church. Being raised by Church leaders,
Copernicus wished to offend no one, so he withheld publication of his treatise until near
his death.
His fears were well-founded, as some later Copernicans found to their cost: one of them,
Giordano Bruno, was burned at the stake in Rome in 1600. (This was only one of Bruno's
crimes in the eyes of the church, but it certainly was a serious one.) Finally, Copernicus'
book was placed on the Papal Index, where it remained until 1835. Nicolaus Copernicus
was the individual who developed a heliocentric model of the solar system and took the
chance of sharing his ideas publicly. While the tiny book was quickly banned for public
reading through an edict of the Pope, there were a few curious minds who found the
heliocentric idea of great interest. To see how the Copernican model was proven correct,
move on to the page which tells a remarkable story of an egocentric astronomer named
Tycho Brahe.
Copernican Revolution Continued - Tycho Brahe
Ironically, the next main character in the story, Tycho Brahe, was no Copernican; he
preferred a hybrid theory which satisfied almost nobody. This Danish nobleman became
interested in astronomy when a "new star" suddenly blazed out in the constellation
Cassiopea. Known today as a nova, it was considered unique in the history of astronomy.
This star was far brighter than anything else in the sky and could even be seen in the
daylight. It was a very confusing event for philosophers. Some speculated that it was the
reappearance of the Star of Bethlehem, announcing the second coming of Christ. Others
warned of disastrous evil about to befall earth. Others believed it was a vaporous
exhalation of earth.
Tycho sought to answer these questions. As an observer he was
supreme, and he carefully measured the distance between the nova
and Polaris. He also fixed the location relative to the stars in
Cassiopeia. His results indicated that this star was not a wanderer, but
a fixed star. He concluded that the stars were not invariable. This
teaching was certainly contradictory to the views of the Church which
held that God finished creation after 6 days and then rested. On a side
note here, that Bible reference never presumed that God may have stopped creating ever
after, but merely rested on the seventh day. Church leaders were convinced that creation
was finished with the words, "it was good." To see a new star in the sky went against the
finality of creation and caused quite a stir. Tycho Brahe carefully recorded the changing
colors as the star faded from view through 1572. Stars could no longer be viewed as
unchanging objects. God's creative works were not "finished" at the end of six days.
Furthermore, Tycho's study of comets led him to conclude that the spheres described by
Ptolemy
could
not
be
solid.
He published a short paper De Stella Nova (The New Star) in 1573, and the little book
attracted the attention of Danish King Frederik II. The king offered to build an
observatory on the island of Hveen just off the Danish coast. Tycho also received a
regular source of income as a landlord of some coastal territory, so he was really never in
great want for money. There, for two decades from 1575 to 1595 he compiled a star
catalogue which was much better than any of his predecessors. He also made accurate
measurements of the movements of the planets, particularly Mars. To do this he devised a
more
accurate
instrument
and
hired
much
help.
Because the stars did not appear to move as would be expected if the earth acted like a
planet, Tycho rejected Copernicus' view and proposed his own system. His model (seen
farther down this page) is a hybrid of Ptolemy and Copernicus, and his underlings at his
observatory were not all convinced Tycho was correct. He set the earth, stationary, at the
center, letting the sun and moon orbit around it, but with the five planets circling the sun,
rather than the earth. To see a more detailed depiction of his findings and errant
conclusions, click on the image of Tycho above and to the left. To read a detailed
biographical account, click on Tycho. As the Copernicus biography is poor with
connecting links, so too is the Tycho site, but the webpages of the biography are still
helpful.
Tycho Brahe was a really interesting man. Born into
nobility, he had both money and influence. It was helpful
to have the backing of the king, but with the gain of
money and prestige came an ego which was enormous.
Some legends hold that when students disagreed with their
professor, Tycho would place them in a dungeon beneath
his observatory, and then in stocks. When these students realized the error of their ways,
and after profuse apologies, Tycho would release them to help him continue the work.
On one occasion, while Tycho was studying at Wittenberg in 1566, a rival famed French
mathematician challended the study of Tycho. An argument ensued. When the
Frenchman proclaimed his prowess in mathematics, Tycho's ego was bruised and he
responded to the challenge by proclaiming he was the greater mathematician. A glove
was slapped across the face and a challenge to duel with swords at midnight given to
settle the issue as gentlemen. Tycho lost the battle when the Frenchman cut off the nose
of Tycho with a sword. Forever after, Tycho required a gold nosepiece to fit over the
hole, and a recent stamp of Denmark even shows the golden nose. And to think that these
men were fighting over the right to be called a greater math geek.
The picture to your left demonstrates the method Tycho used to create star maps and plot
the motion of the planets, sun, and moon. He sat at a chair and pointed to a particular star
by name. An assistant would note the vertical angle (declination) of the star, as well as
the location against the horizon (right ascension). The time was duly noted and the
numbers transferred to a sheet of paper according to the celestial coordinates from the
observation. Night after night, Tycho sighted stars and assistants made recordings of data.
Of critical importance to the Astronomy community were the maps of the motion of the
planets in general, and Mars in particular. Tycho's celestial maps were exquisite in detail
and accuracy. Without any doubt, these star maps are his greatest contribution to
Astronomy. While he clearly misinterpreted his data, his research was still helpful, as
those very maps are accurate even to this day. The diagram below shows Tycho's hybrid
model between Copernicus and Ptolemy. It is quite complicated, and although incorrect,
even in the eyes of his assistants, he pushed ahead with his ideas probably the result of
his oversized ego and aristocratic view of himself.
This very egocentrism led to Tycho's demise.
When Frederic II was no longer king of Denmark,
Tycho fell out of favor with his successor son, and
he finally left the island in 1596, far more poor
than before. He returned to Prague and tried to set
up a new observatory, but was still low on income.
He was named imperial mathematician to the Holy
Roman Emperor Rudolph II, and slowly his sense
of prestige returned. He hired a youthful Austrian
mathematician, Johannes Kepler, to give help in
determing the orbital parameters of the planets,
but was so threatened by Kepler's intellectual
prowess that he eventually refused to allow Kepler
access to his voluminous notes. Tycho locked his
notes in a vault for his own safekeeping and to
guard against a rival interpretation.
In 1601, Tycho was at a banquet for the local nobility. Trying hard to regain his status in
the eyes of his former peers, Tycho was conscious of every social grace. Unknown to
him, he was suffering from a bladder infection at the dinner. While he had to relieve
himself, to arise in the middle of the dinner was a gigantic social faux pax. Struggling
mightily within himself to keep from appearing disrespectful and foolish, Tycho sat
dutifully at the table throughout the meal. Finally, his weakened bladder burst. Tycho
became violently ill and died eleven days later. During that time, Tycho asked Rudolph II
to make Kepler imperial mathematician.
I share this information to any students who are still paying attention to all of the reading.
When you are in a classroom and need to relieve yourself, and the teacher or professor
refuses to let you go, you may cite the experience of Tycho and threaten your own
potential bladder burst and potential ugly lawsuit against the obstinate teacher/dictator :)
With no one to safeguard the vault, Kepler got a hold of the notes and over the next nine
years began to reinterpret their data. Tycho had excellent star maps, but incorrect
interpretative conclusions. Kepler made the correct conclusions, to confirm Copernicus
and lay more upon the foundation of the developing Astronomy Revolution.
Once you have completed the study of Tycho Brahe from the CSEP webpage, move on in
this course to the work of Johannes Kepler.
Copernican Revolution Continued - Johannes Kepler
Johannes Kepler, a German astronomer and mathematician was a
mystic, believing that he could by thought alone divine the structure
of the universe. Unlike many mystics, Kepler believed in the need for
accurate observation, though he also practiced astrology. Above all,
he had complete faith in Tycho's observations, and eventually he
found the answer: the planets move around the sun, not in circular
orbits, but in ellipses. He was thus able to draw up the three famous
Laws of Planetary Motion which bear his name, the last of which was
published in 1618. By then the telescope had been invented.
To learn a more detailed account of this incredibly intuitive astronomer, click on his
image to connect to the CSEP site. For now, here is a brief summary of his work. Kepler
joined Tycho Brahe's observatory in 1600 and quickly demonstrated to Tycho that he had
extraordinary academic skills. As you read on the previous page, Kepler was denied
access to Tycho's notes and maps until his Tycho's unusual death in 1601. Upon gaining
access to these notes, it was clear to Kepler that Tycho's model was incorrect. It was also
clear that Ptolemy was quite wrong too. Why, even Copernicus was not completely right,
although he was in principle. To Kepler, Tycho's notes showed that the Sun did occupy
the central spot in the Universe, but the planets do not orbit in perfectly circular paths.
This could be considered heretical in the eyes of religious zealots, but to Kepler, an
elliptical path is no more than a circle with two focal points. In the case of each planet,
the orbital path is an ellipse with the sun occupying one focus, while the second focus
remains empty. This simple leap removed all need for epicycle motion, explaining
changing orbital velocities and varying season lengths. Copernicus was right with the
heliocentric concept, but the need for perfect circles was unnecessary. From 1601-1618,
Tycho made his own observations and referred to Tycho's notes to develop his 3 Laws of
Planetary Motion. A copy of one of his papers is shown below.
Of great interest to the historical storyteller is
Kepler's relationship with the family of Tycho.
While Tycho had an ego which was as big as
anyone, Kepler came from a more poor family
background. His father was a mercenary who one
day never returned from fighting. His mother was
accused of practicing witchcraft, and Kepler
battled the courts for three years to gain her
freedom. He had an extremely sharp mind but also
a humble spirit. When Tycho died, all of the
astronomical instruments and papers, including
the precious star maps and notes of planet motion.
Apparently when Tycho's surviving family
members discovered that Kepler was advocating
the Copernican view, they sued to get the
instruments and notes back. Kepler was forced to
give up the instruments, but he did keep the notes,
and from them derived his laws.
He published his first book, Astronomia Nova
(New Astronomy) in 1609 and another,
Harmonice Mundi (The Harmony of the World) in 1619. In these two books are the three
laws which govern the motion of the planets and which confirm the basic model of
Copernicus. The cover page for the latter book appears to your left. He also wrote about a
nova which appeared in 1604 and was known as Kepler's star.
Kepler's Laws are listed below is short form:
1) A planet moves around the sun in an ellipse, the sun occupying one focus of the ellipse
while the other is empty. One can define an ellipse as a curve, where the sum of the
distances of the point C from the two foci, A and B, is constant. Thus a circle is a special
kind of ellipse where the two foci come together. The father apart one spaces the foci, the
greater the eccentricity of the ellipse
2) The radius vector -- the line joining the center of the sun to the center of the planet -sweeps out equal areas in equal times. The planets sweep out equal areas in equal
intervals of time. This accounts for the earth moving faster in winter when nearest the sun
(perihelion) and slower in summer when farthest from the sun (aphelion). I personally
call this the Law of Equal Pies. No matter how much differently the pie shape becomes, if
the length of time is constant, the amount of pie cut out of the ellipse remains equal.
Maybe this terminology indicates my preference for a good piece of French Silk or
homemade Apple Pie.
3) For any planet, the square of the revolution period (P) is directly proportional to the
cube of the planet's mean distance from the sun (A). The square of the periodic time
(measured in terms of years) is equal to the cube of the mean distance, expressed in units
of the earth's mean distance from the sun, the so-called astronomical unit. p2 = a3.
It is pretty cool to think of such great discoveries and the idea of having a physical law of
nature named after one's self would be a great honor. I thought my doctoral work on
snails was pretty exciting, but few in the science world shared my joy in researching
snails or concern to their struggle against the cold extremes of Minnesota winters. Alas, I
finished my work, few took notice, and no laws bear my name. Not even a measly
asteroid. At least they named one after my uncle Bill Albrecht.
Where are we so far in the history of the Copernican Revolution?
Martin Luther encouraged people to think differently. Instead of blindly accepting what a
priest told them the truth to be, read for yourselves and make your own conclusions.
Copernicus dared to rethink the Ptolemaic geocentric model, proposing a heliocentric
view. Like Luther, he dared to think differently.
Tycho took detailed notes of the motion of planets against the starry background. While
the maps were excellent, he misinterpreted his notes and drew incorrect conclusions. His
failure to listen to the opinions of others is an example of personal ego clouding good
judgment.
Kepler reevaluated the work of Tycho and offered the correct interpretation of the data.
Copernicus was almost completely right. Kepler gave some mathematical proof for the
Copernican model.
You can now move forward to see how Galileo provided visual proof of the Copernican
model.
Copernican Revolution Continued - Galileo
The first great telescopic observer was Galileo
Galilei, an early convert to Copernicanism who
made no secret of his beliefs. From his youth
(birthdate February 15, 1564), Galileo displayed
the traits that were to dominate his life. He
frequently questioned the authority of his
professors, refusing to accept their dogmatic
statements and demanding proof with observation
rather than blind acceptance of some authority
(not much unlike Martin Luther's ideas regarding
priest-only interpretation of the Bible). A great
connecting website which details the discoveries
of Galileo can be found by clicking on his image
to the left, or you can refer to a detailed biography
by clicking on Galileo.
When he was only eighteen and studying at the Pisa, he noticed that the cathedral lamp
oscillated at consistent times, no matter how heavy the object, nor how wide the
oscillations. He verified his findings with his own pulse, and concluded that all which
mattered was the length of the cord. He constructed pendulums which helped doctors
determine pulse rates of patients. He would have continued a promising career in
medicine until he witnessed a supernova in the Serpens constellation in 1604. In the same
observational manner as Tycho, Galileo determined that the star was a fixed star and not
a wanderer.
In the winter of 1609-1610 he made a series of spectacular discoveries. Many students of
Astronomy believe that Galileo invented the telescope. In actuality, the telescope was
invented by a Danish glassmaker. Galileo learned of the invention and ground his own
lenses and constructed his own nine-power telescope. What set Galileo apart from other
telescopic observers was that he took his trained scientific eye and looked at the night sky
with the small instrument. Imagine his amazement at what he saw. He reported seeing
mountains and craters on the moon. He watched the terminator of the moon and
discovered deep craters with pinnacles in the middle. He even estimated their depth and
height to be four miles. He described the dark areas on the moon as being filled with
water
and
he
noticed
the
absence
of
clouds.
Since the moon was considered to be a perfect sphere of crystal, Galileo was sharply
criticized. Undaunted, he continued to study and resolved the seven naked-eye stars of
the Pleiades to contain over 40, and that the Milky Way was composed of millions of
stars.
He looked at the wandering stars and found them to resolve into disks instead of points of
light like the fixed stars. Venus was sometimes a crescent and other times gibbous, an
observation clearly in support of the Copernican view of the solar system. He also
observed the larger satellites of Jupiter, and since these four bodies were clearly circling
the planet, he reasoned that it was a mini model of the solar system.
The motions of the
moons of Jupiter,
as recorded by
Galileo in 1609,
and published in
his paper, Siderius
Nuncus (The Starry
Messenger)
in
1610 is seen to
your right. This
may have been the
most
damaging
blow
to
the
geocentric model
which was being
held on to so
strongly by the
religious leaders in
the Vatican. In
their
collective
reasoning,
God
placed man, the
special object of
His creation, at the
center
of
all.
Suddenly, Galileo
demonstrates that
some
celestial
objects are not
revolving around
the
earth,
but
around
Jupiter.
This was heresy
number one in the
eyes
of
the
Vatican. What complicated matters even more so for Galileo was his contention that
Scripture was compatible with the Copernican view, but only if one understood the
Bible's intention to be more focused on mankind's relationship with God than on attempts
to explain natural phenomenon to its audience. Verses which describe the sun standing
still or moving backward need not be taken literally.
When he wrote of his discovery that the sun had spots in 1611, he was openly denounced.
For the Sun to have spots was considered a blemish on the very person of God. How
could the Sun, giver of life and light and representation of God possibly have dark spots.
This could imply sin in God and therefore was impossible to accept. (Please keep in mind
that the Chinese had been recording sunspots for centuries, but the Great Wall which was
built to keep invading hordes out also served to keep good scientific discoveries in).
Galileo wrote of his findings in several short scientific papers, but more likely it was his
attempts to interpret Scripture for his readers which brought the attention of the Vatican
to bear down upon him. He was quickly brought before Cardinal Roberto Bellarmine
between 1613 and 1616. Galileo was an accomplished and renowned scientist, so the
Church was not interested in creating a large public controversy. However, when Galileo
took his telescope to the rooftops, the Vatican emissaries refused to believe their very
eyes. They claimed that these dark spots on the sun and bumps on the moon were the
result of imperfections in Galileo's glass. Galileo returned with new lenses, but now the
leaders cited the sin of the world blocking the truth from the heavens and tainting the
images of God's creation. Galileo was threatened with excommunication and its ensuing
eternal damnation. Galileo was encouraged to stop publishing and stop promoting his
astronomical discoveries, and his books were placed on the Index of Forbidden Books,
along with the writings of Copernicus. Basically, "keep your mouth shut Galileo, and stay
out of trouble." His papers were banned from public reading, but Galileo was allowed to
continue his research.
In 1624, the newly elected Pope Urban VIII was found to be sympathetic to the science
of Galileo and he began to compose a new treatise on the workings of the celestial
planets. He wrote the Dialogue Concerning the Two Chief World Systems in 1632. In this
work, Galileo wrote of three individuals who were debating the Copernican and
Ptolemaic views from various perspectives ... one being that of the Church. The dialogue
between Salvitari, Sagredo, and Simplicio is really an interesting read, but you can do
this on your own time later. Suffice it to say, Pope Urban VIII was extremely offended by
the manner in which he was presented and the negative light cast upon the Church.
Following the publication of his Dialogues, he was again brought before the Inquisition
in 1633.
The book title page appears to your left, while an
artistic rendition of the Inquisition appears below.
He was brought to in Rome in 1633 and after
heated debate, forced to recant. Instead of burning
Galileo as Giordonno Bruno had suffered in 1600,
Galileo was faced with a potentially more severe
punishment ... excommunication. This meant loss of membership in the Church, eternal
damnation to Hell after death, and eternal separation from God proved more than he
could bare so he recanted and lived the remainder of his life under house arrest.
He was forced to 'curse, abjure and detest' the heretical
idea that the earth moves around the sun condemned to
prison, and required to repeat the seven penitent psalms
once a week for three years. The following day, the Pope
Urban VIII altered the sentence to mere confinement in a
country-house near Rome and reciting Psalms of
penitence. He was later allowed to return to Florence,
where, broken in health and spirit, he still tried to continue
his observations. Her had a school of very talented
students working under his guidance and he continued to write scientific papers, but
without the Scriptural interpretations which landed him before the Inquisition twice. He
laid the groundwork for modern Physics with his final work Two New Sciences. Total
blindness finished his observations in 1636, and he died in 1642 ... the same year Isaac
Newton was born.
A terrific chronology of Galileo accompanies this test, and I encourage you to look it
over.
Galileo was the last great scientist to be persecuted for teaching that the earth is an
ordinary planet. In 1687 Isaac Newton published his immortal Principia, in which he laid
down the laws of gravitation . He also explained many other phenomena, such as the
tides. Described as the greatest mental effort ever made by one man, his book marked the
beginning of the modern phase of astronomy. Newton was also the first to make a
reflector, which collects light by means of a mirror instead of a lens. The mirror had a
diameter of only one inch, but it was the forefather of the great multi-meter telescopes of
today. The revolution in outlook was complete.
You can now move to Sir Isaac Newton and see how this incredible scientist developed
the laws which govern the motion of the planets, and just about everything else.
Where are we now in the history of the Copernican Revolution?
Martin Luther encouraged people to think differently. Instead of blindly accepting what a
priest told them the truth to be, read for yourselves and make your own conclusions.
Copernicus dared to rethink the Ptolemaic geocentric model, proposing a heliocentric
view. Like Luther, he dared to think differently.
Tycho took detailed notes of the motion of planets against the starry background. While
the maps were excellent, he misinterpreted his notes and drew incorrect conclusions. His
failure to listen to the opinions of others is an example of personal ego clouding good
judgment.
Kepler reevaluated the work of Tycho and offered the correct interpretation of the data.
Copernicus was almost completely right. Kepler gave some mathematical proof for the
Copernican model.
Galileo provided the observational proof of the Copernican model and Kepler's Laws, but
at great emotional and spiritual cost.
Sadly, Galileo's papers were placed on the Papal Index as heretical literature. In October,
1994, these papers were removed from that list by decree of the Roman Catholic Church.
While we might cringe to think that it took so long for the Vatican to recognize their
mistake, the real reason for the delay is more subtle. It had long before been recognized
that Galileo was correct. What required such careful consideration was treatment of those
who placed him before the Inquisition and banned the books. Should they have been
punished for their harsh treatment? After consultation for so many years, the issue
apparently was resolved and Galileo exonerated.
*** I received a copy of a fascinating book by Dava Sobel entitled "Galileo's Daughter."
While few of Galileo's works remain, Sobel found the letters which were written to
Galileo by one of his three children, daughter Maria Celeste ... a cloistered nun. Penguin
Group publisher, copyright 2000. ***
The Copernican Revolution Completed - Sir
Isaac Newton
Galileo discovered some of the laws which describe the behavior of
falling bodies, stating that freely falling bodies near the surface of the
earth accelerate uniformly. Although he did not know the exact value,
we now know that in a vacuum, for every second that a body falls, its
speed increases by 980 cm/s. Newton unified these insights by
showing that the force of gravitation that accelerates falling bodies
near the earth is the same force that keeps the moon in its orbit around
the earth and the planets in their orbits around the sun. His principles
of mechanics and the law of gravitation are so general and powerful that in the century
following his death they strongly influenced the prevailing philosophy. Many thinkers
held that the basic rules of nature were finally known, and that all which remained was to
fill in minor details. A philosophy of determinism developed in response to Newton's
Third Law, holding that every action in the universe follows mechanistic laws from
conditions immediately preceding the action.
Newton's view does not explain the motions of electrons around the nucleus of an atom.
For this we need quantum theory. Newton's laws fail when compared to very fast speeds,
as those nearing the speed of light, and to explain these phenomena we need relativity.
However, Newton's Laws still are valid within their frame of reference. We could not
have gone to the moon without knowing his laws. Now, we will try to explain these laws
which are so fundamental to our understanding of astronomy. If you want a detailed look
with links to Newton's Laws and discoveries, click on his image to the left, or you can
also take a look at a nice biographical sketch by clicking on Newton.
Isaac Newton was born January 4, 1643 in Lincolnshire, London. He apparently had his
birth date changed to December 25, 1642 to coincide with the death of Galileo. Newton
believed that God appointed one individual each century to reveal God’s truth in science,
and he was convinced that he was that person to succeed Galileo. He entered Trinity
College at Cambridge in 1661 and so distinguished himself that he was appointed
Lucasian Chair in 1669. The University was closed during the Plague of 1665-1666,
during which time Newton did the math for gravity. Since the mathematical principles of
his day were insufficient to resolve the gravity dilemma, Newton invented calculus that
summer to make his formulas work. However, because he was more devoted to
mathematics and optics, he put the gravity and mechanics word aside until much later.
Robert Hooke (famous for his discovery of the cell) wrote a letter to Newton in 1679
asking for Newton's ideas about planetary motions. In 1684, Edmund Halley met with
Newton and mentioned that he was struggling to explain how a planet moves with regard
to a force which attracts it to the sun. Newton interest in planetary motion was rekindled,
and he explained that he had worked this out years before, but because he lost his notes,
he had to redo the math. He submitted his paper - The Mathematical Principles of
Natural Philosophy, usually abbreviated PRINCIPIA in 1687. Most scientists and
historians ascribe this book to be the greatest single intellectual effort of all time. In it he
describes three laws:
1) MOMENTUM: Every body continues in a state of rest, or of uniform motion in a
straight line, unless it is compelled to change that state by forces impressed upon it.
Basically, a body tends to keep moving, and a stationary object tends to stay at rest.
Momentum is a measure of the state of motion. Momentum depends on speed, and also
on the amount of matter in a moving object, i.e., a car going 30 mph is harder to stop than
a bike going 30 mph.. Newton then defined momentum as proportional to velocity, and
defined this constant of proportionality as MASS. Mass is a quantity that characterized
the amount of material in the body. The product of a body's mass and velocity is constant
if no outside force is applied to it.
2) FORCE: The change of motion is proportional to the force impressed; and is made in
the direction of the straight line in which that force is impressed. If a force acts on a body,
it produces change in the momentum of the body that is in the direction of the applied
force. The magnitude or strength of a force is defined as the rate at which it produces
change in the momentum of the body on which it acts. Where there is no force, the
change in momentum is zero. There are three ways in which momentum can change. Its
velocity can change, or its mass, or both. Since the mass of a body typically does not
change when the force is applied to it, a change of momentum usually results from a
change in velocity. Thus, in the majority of cases: FORCE = MASS x
ACCELERATION. If the acceleration occurs in the same direction as the velocity, the
body speeds up. If the acceleration occurs in the opposite direction to the velocity, the
body slows down. If the acceleration occurs at right angles to the velocity, only the
direction of the motion of the body changes, and not the speed. Gravity accelerates a
body in a direction toward the center of the more massive object, so the body falls faster
and faster.
3) REACTION: To every action there is always an equal and opposite reaction: or, the
mutual actions of two bodies upon each other are always equal, and act in opposite
directions. All forces occur as pairs of forces that are mutually equal to and opposite each
other. Any force which is exerted on an object will have a corresponding force which is
exerted against it. When you push against an immobile car, it pushes back. When your
feet are firmly planted, the reaction force of the car is transmitted through the you to the
earth. Because the earth is so massive, the earth accelerates far less than the car. When a
boy jumps off a table, the force pulling him down is a gravitational force between the boy
and the earth. The boys jumps down 5 feet, but because the earth is so massive, it
responds only a fraction of an amount. The same principal of reaction is seen in a batted
ball and also in a rifle recoil. Here is also the principle of rockets - the force that
discharges the exhaust gases from the rear of the rocket is accompanied by a force that
shoves the rocket forward. The exhaust gases need not push against the air or earth; a
rocket works best in a vacuum. In each case, a mutual force acts upon the two objects
concerned; each object always experiences the same total change of momentum, but in
opposite directions. Because momentum is the property of velocity and mass, the object
of lesser mass will end up with proportionately greater velocity.
Ordinary
momentum
is
the
product
of
mass
&
velocity
Angular momentum is the product of mass, velocity, and the distance of the fixed point
around which an object turns. If you do not change any value, the system perpetuates. If
you reduce the distance, the mass stays the same, but the velocity increases - like a skater
doing a final sitz spin.
Newton's Principia is of such length that it becomes difficult to even give a summary of it
here. A personal friend of mine mistakenly joined a "book of the month club" and began
receiving volumes of the Principia. After an entire year, he was the owner of 21 volumes
of Newton's work. My friend is a swimming coach and has no interest in Newtonian
Physics, so the set sits idly on his bookshelf in the loft of his home.
THE LAW OF UNIVERSAL GRAVITATION was perhaps his most important
contribution to Astronomy. Kepler nearly discovered this force. Galileo demonstrated the
property of gravity in his experiments and papers on falling bodies. Neither were able to
solve the mathematical explanation for such observed actions. Legend hold that an apple
fell on Newton's head while he was resting near a cemetery. Newton pondered the fallen
apple, and then looked at the adjacent graves and recognized the "gravity" of this apple's
demise, and hence the name came to his head. In reality, apples may have fallen on
Newton's head, but they did not incite great interest. Newton applied his motion laws to
the orbit of the moon. He reasoned that the moon should be moving in a straight line and
continue to do so unless acted upon by another force. Somehow, another force must be
causing the moon to follow a curved path, and do so indefinitely. The moon is not
orbiting around the moon as much as it is falling toward the earth an exact distance equal
to the distance it is moving forward in a straight line. There must be a force between earth
and moon which is causing the forward and downward motions to result in a curved path,
and he described this force as the mutual attraction, or "Gravity" between earth and
moon.
Between any two objects anywhere in space there exists a force of attraction that is in
proportion to the product of the masses of the object and in inverse proportion to the
square of the distance between them.
F = G m1m2/d2
F is the force of gravity between two objects of mass, m1 and m2
G is Newton’s constant number which is in every equation to make the math work
(G = 6.67 x 10-11 N m2/kg2)
m refers to the masses of the two bodies between which gravity acts
d is the distance between those two bodies of mass
If knowing the force of gravity between you and the earth, as well as the speed you would
need to jump at in order to escape the earth's gravity is not relevant to you, then consider
your dating relationship ... if you have any. Your attraction to that significant other is
merely a physical force called mutual attraction or gravity. The closer you get, the
stronger the force, and significantly so due to the effect of the squaring of the distance
between you two. The continuing approach of two of you toward each other, resulting in
the loving embrace and tender and compassionate kiss is merely reduced to a physical
force of gravity which can be mathematically explained. Your date might be lost in
emotional thoughts, but your mind is pondering the strength of the gravitational force.
You want desperately to learn about the possibility of a long-term relationship but in
order to solve the math, you need to know the mass of your partner. You stop the kiss and
embrace and ask the all-important question, "What is your mass in kg?" This results in a
slap to your face and a most certain termination to your relationship. If your date is just as
excited about knowing the force of gravity with you, then you know you are well on your
way! Love is nothing more than gravity. Instead of flowers, you may exchange handheld
calculators on your anniversaries and live happily ever after.
Newton derived many other mathematical formulae, but two more are given below. The
first describes the manner in which anyone can determine the velocity of escape from any
object of mass in space. The second describes the velocity necessary to be achieved in
order to reach a stable orbit around any given object of known mass and radius.
Ve = √2GM/R) Vo = √GM/R)
The other gives the orbital velocity for any planet whose circumference of orbit is known.
V = 2(Pi)r/P
where P is the orbital period measured in years, as in Kepler's Three Laws.
From these Laws, you can discover the force of Gravity between you and the Earth,
assuming you know your mass in kg, since the mass of the Earth is 59.74x1023 kg, and
the distance between you and the center of the Earth is 6388 km. Of critical importance
here is to remember the units which are used in these formulae. The units of mass are
measured in kilograms (kg), but the units of distance are measured in meters (m), so the
radius would need to be multiplied by 1000 to allow the equation to work.
As you read in the text of these laws and others, keep in mind that gravity is so very
important in understanding how celestial objects move, and how stars work. Newton was
a brilliant man, some even contending that he was the most intelligent man of all time,
but alas with all of his brain power, he had a few shortcomings. Sir Isaac believed that he
was the singular appointed spokesman from God to the world, and that only he had
correct interpretations. He did not endear himself to many fellow scientists due to his
own arrogance. He also practiced alchemy in a vain attempt to convert lead into gold.
Review of science/religion clash:
The early history of astronomy also offers a peek into a terrific struggle for power
between the Roman Empire and the Holy Roman Empire. While the emperor controlled
the people with military strength and taxes, the Pope controlled the people with religious
regulations and fear of eternal hopelessness. The Reformation and the Astronomical
Revolution were in the same century and common people began to rethink ideas which
had gone unchallenged during the previous millennium. It was just as important to
accurately interpret the Scriptures as Martin Luther was asking as it was to accurately
interpret celestial motions as Copernicus was asking. Both men believed in a literal God.
Both were soundly criticized by the Roman Catholic Church. Both men dared to ask
questions and offer alternative viewpoints than those widely held but poorly defended. In
my in-house Astronomy class, we would watch the movie "October Sky," not only
because it is a true story, but to demonstrate the power of new thinking. Homer Hickum
dared to think he might use his mind to get a scholarship and get out of Coalwood. For
years, football was the only ticket to college, and most worked the mines. Homer built
rockets, went against his own father. He was inspired by a teacher to dream big, solve
problems, and stick with his hopes. The same principles which resulted in the entire
world being turned around by the writings of Martin Luther and Nicolaus Copernicus
should give anyone today the same encouragement. Dare to think different. Dare to
dream big. Then dare to do something about it.
Below is a short list of questions which can also be accessed at the Copernican
Revolution Quiz.
1. How was the solar system model of Copernicus different from that of Ptolemy?
How was it similar?
2. When did Copernicus publish his theories, and why did he wait so long to do so?
3. What was the value of Martin Luther's departure from Roman Catholicism to
Copernicus?
4. What was Tycho Brahe’s greatest contribution to Astronomy?
5. What happened to Tycho's nose?
6. How did Kepler correct the heliocentric model of Copernicus?
7. Which particular discovery of Galileo most angered Church leaders?
8. Of the 3 variables in Newton’s Law of Gravity, which will have the greatest effect
if changed?
9. What is the force of gravity between you and the cloudtops of Jupiter.
10. What lesson can be learned from the writings of Martin Luther and Nicolaus
Copernicus?
You have completed the History of Astronomy Unit. By no means do I believe this unit
to be complete, but it will serve to give you a feel for the tremendous upheaval caused by
the Copernican heliocentric model.
Martin Luther encouraged people to think differently. Instead of blindly accepting what a
priest told them the truth to be, read for yourselves and make your own conclusions.
Copernicus dared to rethink the Ptolemaic geocentric model, proposing a heliocentric
view. Like Luther, he dared to think differently.
Tycho took detailed notes of the motion of planets against the starry background. While
the maps were excellent, he misinterpreted his notes and drew incorrect conclusions. His
failure to listen to the opinions of others is an example of personal ego clouding good
judgment.
Kepler reevaluated the work of Tycho and offered the correct interpretation of the data.
Copernicus was almost completely right. Kepler gave some mathematical proof for the
Copernican model.
Galileo provided the observational proof of the Copernican model and Kepler's Laws, but
at great emotional and spiritual cost.
Finally, Isaac Newton provided mathematical proofs and explanatory Laws which
confirmed the heliocentric model and Galileo's observations. The Astronomy Revolution
was completed ... and all accomplished between 1543 and 1687! I once again cannot
emphasize enough the power of original thought..
A general overview of the universe as we now know it to be.
Sun is center of solar system
Nine planets revolve around the sun
Ninety-one known moons are orbiting the planets
Planets and moons are mere reflectors, while the sun is a light and heat creator
The Sun lies in an arm of Milky Way
The Milky Way contains approximately 200 billion stars
Stars differ in composition, size, temperature, energy output, and age
Vast distances separate stars and even greater distances are between neighboring galaxies
We measure distances to planets in our solar system in Astronomical Units
1 AU = distance from earth to sun = 149,600,000 km
We measure distances to stars and galaxies in Light Years
1 LY = distance light travels in 1 year = 300,000 km/sec x 60 sec/min x 60 min/hr x 24
hr/day x 365.25 day/yr = this is over 9,400,000,000,000 km