Last week, I wrote about the deep roots of the European Renaissance, the time to our modern society can trace its origins. In short, by the mid 1400s, Europe was ripe for an intellectual revolution that would, literally, reshape the universe as we know it.
Nicolaus Copernicus.
The first great astronomer of the
Renaissance was Nicolaus Copernicus (1473-1543), who is widely
considered to be the first great astronomer since antiquity because
it was Copernicus who proposed the idea of a heliocentric, or
Sun-centered, solar system. Actually, the idea that the Earth was a
planet and all planets revolved around the Sun was an old hypothesis
first put forward by Aristarchus of Samos in the 300s B.C.
Unfortunately, unable to ponder the inconceivable of why there was no
great wind thanks to Earth's motion and that the stars could have
been infinitely far away, the ancients disregarded Aristarcus' ideas
in favor of the more practical, Earth-centered theories put forth by
others.
Ironically, if not for a colleague,
German astronomer Georg Rhericus, Copernicus' ideas may have never
made it outside a very small circle of friends. After returning to
his native Poland after a trip to Italy, Copernicus wrote a short
work on a heliocentric solar system that he distributed only to his
friends (being a clergyman himself, Copernicus undoubtedly realized
the offensive nature of such an idea). In time, this short work
became the revolutionary work On the Revolutions of the Heavenly
Orbs, which finally went to print in 1443. Copernicus himself
received the first printed copy on the day he died.
In analyzing Copernicus, he had some
important motivations for developing his heliocentric idea. First,
Ptolemy's geocentric solar system was complicated and it was often at
odds with observations. When it came to arguing for heliocentricism
(and perhaps avoiding getting himself into trouble), Copernicus
didn't flat out say that he was right and his opponents wrong, but
that his theory was just that, a theory, and one that couldn't be
proved or disproved any more than geocentricism. Unfortunately, just
like with Aristarchus 2,000 years before, critics came out of the
woodwork to argue against Copernicus. The fact that Copernicus
himself was dead by the time his book was printed didn't help
matters, either. As with Aristarchus, opponents argued that, if the
Earth moved, there should be a constant wind, or at the very least, a
noise. If the Earth spun on its axis, why didn't objects dropped
always land to the West of where they fell? If earth moved, why
wasn't there any detectable stellar parallax/brightness change in
stars? These ideas plus the unprovable nature of it, the fact that it
couldn't explain anything Ptolemy's system couldn't, and the 2,000
year history of Geocentricism all conspired to keep the ideas of
Copernicus out of the scientific forefront.
Tycho Brahe.
The next three giants of Renaissance
astronomy would be contemporaries, albeit in different locales. The
first to become a scientific star was Tycho Brahe (1546-1601), a
Danish nobleman with a zest for science. Having observed a supernova
in 1569, Brahe's book about the event brought him to the scientific
forefront virtually overnight. With such fame, Brahe became a hot
commodity whose skill as an astronomer was sought by many nations. To
keep him from going abroad, the Danish king gave Brahe his own island
plus a considerable royal allowance to be used in the pursuit of
science. Brahe did not disappoint his royal patron.
Using his allowed money to build a
permanent observatory, construct the world's largest (and therefore
the ability to make the most accurate measurements) instruments), and
hire trained assistants, it is little wonder that Brahe was the
greatest of all the pre-telescopic astronomers, compiling more than
10 times more data than all the other astronomers who had ever lived
to that point, combined! Adding to the quality of his reputation,
Brahe's instruments were permanently mounted and multiple
observations were made for verification. Single-handedly, Brahe
corrected the error-ridden astronomical charts compiled by previous
generations of astronomers.
Naturally, being such a big name in
the scientific community, it was only natural that Brahe would weigh
in on the whole shape of the solar system debate. In his solar
system, Brahe went for a compromise model. The Earth was at the
center but all the other planets went around the Sun, which went
around Earth. However, unlike previous astronomers who had discounted
heliocentricism without much thought, Brahe was sure to examine the
theory before discrediting it. First of all, even with his huge
instruments that could measure to accuracies previously unimaginable,
Brahe could still not detect any stellar parallax. Also, in trying to
measure the angular size of the stars, they were several minutes of
arc. Even at an unimaginably distant 7,000 A.U.s, the stars
themselves would have to be several A.U.s across, far too large for
Brahe to comprehend. Result: the compromise solar system, which would
hold sway for around 100 years.
Johannes Kepler
At the same time that Brahe was
measuring the heavens, a German, Johannes Kepler (1571-1630), was
just getting his career started. Like with Copernucus before him,
Kepler could have easily never became an astronomer. Initially sent
away from home to study theology and become part of the new Lutheran
clergy, Kepler instead found himself drawn to mathematics, which soon
became his field of study. Upon graduation from college, Kepler found
himself teaching high school mathematics, with astronomy being as a
spare, side interest. Despite astronomy not being his profession,
Kepler wrote a book on the topic, specifically planetary orbits. This
work attracted the attention of many astronomers, including Brahe,
who invited Kepler to join his staff.
Brahe was an astronomer, not a
mathemitician, and he knew that he needed Kepler's mathematical
genius to make sense of his volumes upon volumes of data. At the same
time, Kepler knew he needed Brahe's data if he were to make any
discoveries. Unfortunately for Kepler, Brahe, probably rightly so,
regarded his observational data as his life's work and wasn't about
to start giving it out freely. Between the time he joined Brahe's
staff in 1599 to the time Brae died in 1601, Kepler almost quit his
position several times over frustration about not being granted
access to the volumes of data Brahe had compiled in over 30 years of
observations.
After Brahe died, though, Kepler
would be appointed to Brahe's position of Imperial Mathemitician,
which thus granted Kepler access to all of Brahe's data. Eagerly
plunging into his work, Kepler immediately came across problems,
specifically that the observational data could not be reconciled with
planets having a circular orbit. In the time that followed, Kepler
tried various models for planetary movement in the hope of finding
one that would fit the observations. Try as he might, Kepler just
couldn't reconcile the models to the observations, especially in
regards to the planet Mars, which exhibited the greatest irregularity
in its orbit.. Finally, in desperation, Kepler, a deeply religious
man who sought to find proof of a divine blueprint for the solar
system, gave up the perfect circles that had so dominated astronomy
for centuries. Upon calculating the orbits of the planets as ellipses
(slightly elongated circles) the observation and theory finally
agreed. It was this discovery that planets' orbits ere elliptical
that inspired Kepler's 3 laws of planetary motion.
Law 1: All planets move in elliptical
orbits with the Sun at one of the foci.
Law 2: All planets move through equal
areas of space in equal times ()basically, planets move faster when
closer to the Sun and slower when farther away).
Law 3: A planet's period of orbit is
proportional to its distance (orbital period (in years) of the planet
squared equals the semimajor axis (in AU) cubed). This discovery
showed that there was some common force governing planetary motion
(this force is gravity, but Kepler didn't know this yet).
While his 3 Laws were undoubtedly
important to the development of astronomy, Kepler also left a
historical footnote among his already rich legacy to mankind: the
world's first work of science fiction. In The
Somnium (Dream in Latin), Kepler details a trip to the
Moon, the lunar environment, and its inhabitants. Unfortunately, in
the mid 160=10s, a partial copy got out to the public, which sparked
rumors of witchcraft about the Keplers, with many people accusing
Kepler's mother (who fit the stereotypical image of a witch in the
fact that she was old, lived alone, sold herbal medicines, and had a
quarrelsome personality) of using her magic to transport her son to
the Moon. To make matters worse, this was the “Burning Time,” the
height of the witch hunts when clergymen relentlessly pursued
so-called witches, employing torture to extract confessions before
often burning the unfortunates at the stake. In reality, the (un)Holy
Inquisition was more of a womens' genocide. In some villages, only a
handful of women were left alive after the inquisitors passed through
and this was the environment in which Kepler's science fiction found
itself.
Not surprisingly, the rumors got to
the ears of the church leaders who then ordered Kepler's mother
arrested. In the middle of the night, the authorities cam,e fore
Katherine Kepler, forced her into a chest, and then carried her off
to prison, which is where she would spend nearly the next 5 years. It
was only through years of legal wrangling that Kepler was finally
able to get his mother out of prison. Not surprisingly, Kepler blamed
himself to an extent for his mother's legal woes and, after the court
battle was over, Kepler put the
Somnium aside for the better part of a decade, sticking to
science fact instead. Finally, in the mid 1620s, Kepler started
writing again but, just as he was about to publish, he died suddenly
in 1630. The Somnium was published by his son in 1634, the
only edition that would find its way to print for over 200 years.
Galileo Galalei.
At the same time that Kepler was
battling the forces of the Inquisition while trying to paint an
accurate picture of the cosmos, another, very different type of
scientist, was conducting work in Italy that would, in time, come to
gain him the title “father of modern astronomy.” This man was
Galileo Galalei.
Like his contemporary Kepler, Galileo
was drawn to astronomy through mathematics. Earning a mathematics
degree, Galileo would go on to a university teaching career in Pisa.
Unlike Kepler, who was motivated by a purely intellectual desire to
discover, Galileo's initial motives were financial. Despite its high
prestige, the position of university professor was not the best
paying job in the world and Galileo was short on money, especially
considering the fact that he was supporting a secret, second family
as well as his wife and children with her. The avenue or financial
success: a new invention called the spyglass.
An early telescope owned by Galileo.
Invented by an unknown Dutch lens
maker who discovered that great magnifications could be achieved by
the right pairing of lenses, the spyglass was the father of the
telescope. In fact, the Dutch were the first to turn the spyglass
skyward, and they reported far more stars than could be seen with the
naked eye. Being a mechanical mind, Galileo resolved that, if he
could get a spyglass and improve the design, he could make a lot of
money by selling his design to the military. Well, Galileo did get a
hold of and improve upon the spyglass, but his legacy would be far
more than as a salesman.
Being naturally curious, Galileo
gained worldwide fame for the fact that he was first to turn the
improved spyglass, now dubbed the 'telescope,' to the sky, thus
becoming the first telescopic, and thus modern observational
astronomer in history. Finally, after centuries as a theoretical
abstraction, the sky and the bodies it contained would become places.
In his book, the Starry Messenger (written in the vernacular
Italian, not Latin as all previous scientific works were), Galileo
both forever changed the picture of the universe through undeniable
visual observations and the way which people perceived science
through writing in everyday language.
In the Starry Messenger,
Galileo made several major discoveries. Starting with the least
Earth-shaking, the Milky Way cloud transformed itself into rich
fields of tiny stars, far more than the eyes could ever count. In the
telescope, the stars looked the same as they did visually, with no
details, which implied that Aristarchus and Copernicus were right,
the stars were infinitely far away. Last, the angular sizes of the
stars were greatly over-estimated by non-telescopic observers,
including the great Tycho Brahe.
One of Galileo's drawings of the Moon.
Moving up into slightly disturbing,
Galileo discovered that the heavenly bodies were not perfect and
unchanging. The Moon was found to have mountains, valleys, plains,
and dark areas, hardly a perfect world. As for unchanging, Galileo
found that the Sun was not some static, unchanging body, but a disc
covered with dark sunspots that moved across the Sun itself. By
watching the sunspots, Galileo deduced that the Sun spun on its axis
about once a month.
Now for the heretical.
Galileo's observations of Jupiter's moons.
When turning his telescope on Jupiter, Galileo found that the planet was accompanied by four tiny specks that moved with it through the stars, changing position relative to each other, but staying with the planet. It took no time for Galileo to realize that2 these tiny specks were moons, thus disproving the long-held idea that everything revolved around the Earth. However, geocentricism was not dead. Okay, so maybe not everything orbited Earth, but there was still no irrefutable proof that the Earth was a planet that went around the Sun.
Galileo's drawings of the phases of Venus.
Galileo's next discovery, the phases
of Venus, provided such proof that Earth is not the center of the
solar system. In a geocentric solar system, Venus would always be
some sort of crescent thanks top the fact that the Sun orbited Earth
with it. Ina heliocentric solar system, Venus would go through a
full range of phases, just like our Moon. Well, in turning his
telescope on Venus, Galileo found that it did exhibit a full range of
phases from a thin crescent to a nearly full disc (new and full are
obscured by the Sun). Now, while today, the only logical conclusion
can only be that the solar system was heliocentric, back then, there
was the third model proposed by Tycho Brahe: that which had the
Earth at the center, the Sun orbiting our planet, but all the other
planets orbiting the Sun. Now, as awkward as that idea is (why would
the Earth, of all planets, be so special?), it held sway until around
the year 1700 and the advent of Newtonian physics, which we will
address later.
Now, these discoveries in themselves
were disturbing enough for scholars and theologians but, to make
matters “worse,” Galileo published all of these findings in the
vernacular Italian, the language of the masses, rather than in Latin,
the language of the educated. In doing so, Galileo became the first
great popularizer of science, but the cost would, in time, be great.
When Galileo published the Starry
Messenger, the Catholic Church, long the unchallenged, dominant
religion of Europe, was in a bad way. The Protestant Reformation had
begun in 1517 when Martin Luther published his 95 Theses,
which directly challenged the authority of the catholic priesthood
by stating the, at the time blasphemous idea, that salvation could be
achieved through a personal relationship with God, thus negating the
middleman that was the Catholic priest. Its authority challenged, the
Church immediately clamped down on all opposition, which included
science as, back then, theology and science were tightly intertwined.
Remember, if the Bible said something was true, it was true, the
observations to the contrary be damned, literally. As a result, the
Church went on a frenzy of squashing anything that challenged its
doctrine or world view. In 1616, just a handful of years after Starry
Messenger was published, pope Paul V declared the teaching of
heliocentricism to be heretical. His justification: the Book of
Joshua in the Old Testament, which plainly stated that, with God's
aid, the Sun was made to stand still, thus implying that it, not the
Earth, moved. Shortly thereafter, cardinal (now saint) Robert
Bellarmine personally warned Galileo to stop teaching
heliocentricism. For the time, Galileo heeded this advice and did
other work, which included pioneering experiments in physics.
In 1624, Paul V died and was
succeeded by Urban VIII, an old personal friend of Galileo. Seeing
this change at Church helm being to his advantage, Galileo approached
Urban VIII about heliocentricism. Urban, who was, for the time,
rather progressive in his thought, gave Galileo the okay to write
about a Sun-centered solar system under one condition:
heliocentricism was to be discussed as a theory, nothing more. Taking
this approval, Galileo proceeded to write the Dialogue,
subtitled Concerning the Two Chief World Systems, the Ptolemaic and
Copernican, which was published (also in the vernacular Italian) in
1632..
In the past when autocratic
governments/religions were the norm, writing about controversial
topics in the form of a dialogue (more accurately a debate) was a
great way to avoid getting oneself in trouble, provided that the
debate was actually balanced. Plato did this in an increasingly
intolerant Ancient Greece (remember, Plato's teacher, Socrates, was
condemned to death for, among other things, blasphemy and, according
to the charges, corrupting the Athenian youth with his teachings) and
never got himself in legal hot water. Obviously, Galileo sought to
emulate writers like Plato in his Dialogue. Unfortunately,
Galileo's debate was anything but balanced, with the character
supporting the Earth-centered model and using Church arguments even
being named Simplicio (“simpleton” in Italian).
Needless to say, the Church wasn't
happy.
Summoned before the (un)Holy
Inquisition and threatened with torture, Galileo, then 69 years old,
confessed that his teachings had been in error and that he was guilty
of religious crimes. The Church, in reality, came down rather lightly
on Galileo, sentencing him to house arrest in his palatial villa for
life (they could have sent him to prison or, like Giordano Bruno, had
him burned at the stake) and placed the Dialogue on the
Church's list of forbidden books (where it would remain until 1822).
With such an influential scientist treated in this manner, it was
little wonder that no scientist in Italy dared speak of a
Sun-centered solar system even as the idea was becoming widely
accepted in the rest of Europe. As a postscript, the Catholic Church
never admitted its injustices toward Galileo until 1993, when he was
formally declared innocent of the charges. In thanks to Galileo, 2009
was declared the International Year of Astronomy as it marked the
400th anniversary of Galileo turning the spyglass skyward.
More Ancient
Astronomy
The Planet of Bethlehem?
A History of Cosmology: Prehistory to Present
Galileo's Fingers Go on Display.
Renaissance Astronomy: Part 1
Renaissance Astronomy: Part 2
Renaissance Astronomy: Part 3
The Equinox and a Magic Show from the Maya
Ancient America: the Moundbuilders
Ancient America: the Southwest
Ancient Egypt
Classical Greece
The Summer Solstice Sun and the Size of the Earth
The 1833 Leonids: History's Greatest Meteor Storm
The 10 Brightest Comets of All Time
Ben Franklin and the Truth About Daylight Savings Time
The Planet of Bethlehem?
A History of Cosmology: Prehistory to Present
Galileo's Fingers Go on Display.
Renaissance Astronomy: Part 1
Renaissance Astronomy: Part 2
Renaissance Astronomy: Part 3
The Equinox and a Magic Show from the Maya
Ancient America: the Moundbuilders
Ancient America: the Southwest
Ancient Egypt
Classical Greece
The Summer Solstice Sun and the Size of the Earth
The 1833 Leonids: History's Greatest Meteor Storm
The 10 Brightest Comets of All Time
Ben Franklin and the Truth About Daylight Savings Time
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