Early Astronomers
The history of astronomy goes back several thousand years ago.
Almost all ancient cultures had stories about how the universe
was created, what it was like, who created it, and how the earth
and humans got here, but those stories are usually not very
believable. The early Egyptians believed that the universe was a
large rectangular box with Egypt at the center of the bottom and
with huge lamps which hung down from the top for stars. The ideas
of the other cultures which were near Egypt usually had the same
concept of an enclosed space with that culture’s part of the
world at the center. One major factor holding the ancient
cultures back from developing the technology to look farther into
the cosmos was their belief in many unpredictable gods who
controlled the universe. If the universe was unpredictable
because of gods, why try to understand it if what you learned
could become obsolete at the whim of the next god. The only
culture that worshipped one God who made a predictable universe
at that time were the Jews. The Bible, which came from that
culture, later had a profound positive impact on science.
Some of the astronomers in the ancient cultures kept records
of their observations. The Chinese have records going back to
about the 1300s B.C. By about 700 B.C., the Babylonians could
predict certain heavenly events. By about 600 B.C., the Greeks
started to get interested in astronomy.
The Greeks
The first ancient culture that usually comes to mind as being
more aware of the truth of their surroundings than other cultures
of that time period are the Greeks. In fact, our word astronomy
comes from the Greek words meaning "law and order". The
Greeks were not the first culture to try their hand at astronomy
but the work of their philosophers was widely distributed by the
Romans and was the accepted authority on that subject for
hundreds of years. The Greeks discovered that the earth was a
sphere by several methods and the philosopher Eratosthenes
measured the circumference of the earth to within about 300
kilometers of today’s generally accepted value. In about 200
BC Aristarchus first stated that the earth revolves around the
sun but most philosophers argued that everything revolves around
earth.
There were apparently also some cultures about which we know
little who were interested in astronomy. Stonehenge and the
various other similar structures which appear to be ancient
calendars are some examples of monuments built by those groups.
Ptolemy
Around 150 A.D. Ptolemy (100?-165? A.D.), an Alexandrian
astronomer, invented the concentric system to explain the motions
of the planets around the earth. His work was the accepted
authority on astronomy until 1543.
To fully understand why some of the early modern astronomer’s
ideas were not accepted and why some of those ideas led the
astronomers to be ridiculed, it is helpful to have a background
on what was happening to the culture at that time.
For a time under the Romans, from about 300 BC to 476 AD,
there was a decline in the study of astronomy in favor of
astrology and some of the works of the Greek philosophers were
destroyed.
Modern Astronomy
The modern history of astronomy starts in Europe in about 1300
AD. Before that time, the Roman Catholic Church had been the
dominant religion in Europe and at times had more control over
countries than did the kings of those countries. The Roman
Catholic Church started in about 300 AD under the Roman emperor
Constantine. Over time, the popes started getting more powerful
because of the fact they were the heads of a religion followed by
most of Europe and gradually replaced the empire as the center of
power. During that time, some of the popes introduced some
controversial beliefs to increase their power and the popes and
most of the clergy became corrupt. By the 1200s, it was obvious
that most of the clergy were more interested in gaining political
power than in helping the people spiritually.
In 324 AD, the Roman emperor Constantine moved the capital of
the Roman empire from Rome to the city of Byzantium, present day
Istanbul, and renamed it Constantinople. As he built up his new
capital, he collected and stored many of the ancient writings of
the Greek philosophers in libraries in the city. In 395 AD, the
empire split up into two parts. The eastern half had its capital
in Constantinople and was called the Byzantine empire. The
western half had its capital in Rome. The church also split into
two parts; the eastern half was called the Eastern Orthodox
Church and the western part was called the Roman Catholic Church.
Each church also had its own pope and very different ideas. In
about 476 AD the western half of the empire was destroyed by the
Visigoths, Vandals, and other Germanic tribes. Southern Europe
was then plunged into what is now called the Dark and Middle Ages,
which was marked by frequent wars and a lack of strong
governments. During that time, not much learning at all occurred
and most of the population lived under lords as serfs. The
priests of the Roman Catholic Church, however, kept education
from dying out completely during that time. The eastern empire
stayed together for another thousand years until 1453 when the
Ottoman Turks captured Constantinople. Before the Turks could
capture Constantinople and make it into Istanbul, however, most
of the population fled the city, taking with them the works of
the ancient Greek philosophers. As the knowledge from the city
spread throughout Europe, it helped start what is now called the
Renaissance.
The Renaissance
The Renaissance, which took place from the early 1300s to
about 1600, was a time in which people in southern Europe began
to learn, which had not taken place there much since the western
empire fell. As the people started to learn, they saw the
corruption of the Roman Catholic Church which led them to turn
away from it altogether and to start pursuing the improvement of
themselves with knowledge. They got much of that knowledge from
the monasteries of Catholic Church which had preserved most of
the books written before that time.
Starting in the 1500s, the learning from southern Europe began
to enlighten the people in the north. In northern Europe, however,
when they saw the corruption of the church, instead of turning
away from the church, they tried to reform it. This period is
called the Reformation. During the Reformation, people began to
read the Bible for themselves, which the Roman Catholic Church
was supposed to be based on, and found beliefs in the Bible which
they thought were contrary to the beliefs of the church. Some of
these people started the Protestant movement. Many thousands of
people were killed, usually being burned as heretics, because of
their belief in things which were contrary to what the pope, who
set the beliefs of the Catholic Church, said. The Catholic Church
was still very powerful and one of the beliefs that the pope set
is that the earth itself is the center of the universe and that
all other heavenly bodies revolve around it. This is the reason
that the church persecuted those who believed Copernicus’s
ideas about the sun being the center of the solar system.
The printing press was invented in the year 1430 which helped
spread information about all of the sciences. This made the
common man able to afford a book, which before then had to be
handwritten and thus were very expensive. By this time, most
educated people were aware that the earth was a sphere.
Copernicus
About that time a Polish canon of ecclesiastic law and
astronomer named Copernicus (1473-1543) began to wonder if there
could be a more aesthetically pleasing and reasonable arrangement
for the planets than the concentric system. He studies
Aristarchus’s heliocentric ideas and built a new system out
of it. He developed a system where all of the planets, including
earth, orbit the sun and where each one of these orbits was in
the shape of a circle with the sun at its center. After almost
forty years of study, he published his monumental book On the
Revolutions of the Heavenly Orbs in 1543, the year he died. He
was never able to prove his ideas but later advances in physics
would make it possible to prove a version of those ideas.
Copernicus’s book caused an amazing amount of controversy.
Martin Luther attacked his book by saying that Copernicus was
"the fool who would overthrow the whole science of astronomy."
Religious leaders attacked the heliocentric system by saying that
they were contrary to scriptural revelations. The publisher of
his book even inserted an anonymous apologetic note the readers
of his book implying that his ideas were far fetched. Since the
heliocentric cosmology was contrary to church ideas, advocating
Copernicus’s ideas was punishable as heresy so the
scientific community at that time was extremely reluctant to have
anything to do with it. Philosopher Giordano Bruno committed this
"crime" and was burned at the stake.
Copernicus’s ideas were not perfect because, since he
believed that the planets move in perfect circles, he had to
insert some epicycles and other mathematical structures into his
theory which made it about as inaccurate as Ptolemy’s system.
However, Copernicus’s theory was a tremendous leap in
astronomy.
The next person to make an advance in astronomy was Tyco Brahe
(1546-1601). With help from King Frederick II, he built an
observatory on the Island of Hveen that was equipped with the
most accurate pre-telescopic instruments for observing space ever
built. He was able to determine positions of objects to within
one minute of an arc, far more accurate than any previous attempt.
Brahe constructed an uninterrupted record of the positions of
many planets and other bodies for several years, but he did not
accept Copernicus’s ideas. His idea of the universe was a
compromise, he believed that the five planets orbited the sun,
but the sun orbited the earth. He reasoned that the motion of the
earth would be felt and he thought that Copernicus’s ideas
were unscriptural.
Kepler
As the Renaissance was coming to and end, a German man named
Johannes Kepler (1571-1630), who
believed Copernicus, started
looking at the records of Brahe’s observations. He
discovered that none of the ideas presented thus far about the
motions of heavenly bodies lined up to the evidence in Brahe’s
records so he formulated his own ideas. After seventeen years of
work, he finally came up with the true motions of the planets and
published them in two books in 1609 and 1619. He discovered that
the planets move around the sun in ellipses with one focus of the
ellipse at the center of the sun and the other focus at a usually
unoccupied point in space. He also came up with rules for their
movements called Kepler’s laws.
Because of Kepler and Brahe, astronomers now had a model for
the solar system that actually fit the evidence and that could be
used to predict future events or reconstruct past ones. This was
a giant leap for astronomy but the work still remained to give
reasons for what Kepler observed.
Galileo
Living at the same time as Kepler, an Italian named Galileo
Galilei (1564-1642) made the next breakthrough for astronomy.
Galileo is probably best known for some experiments with falling
objects from the leaning tower in Pisa, his home town, but he
also made some exciting discoveries with his homemade telescopes
and experimented with pendulums. Galileo was also a believer in
the Copernican theory. Since Ptolemy first made up his concentric
model, many people argued that Ptolemy’s theory must be true
because they reasoned that the earth would leave the moon behind
if it traveled around the sun. In 1610, Galileo made the
discovery with his telescope, which was the most advanced at that
time, that Jupiter had at least four moons orbiting it. This was
proof against the concentric system because Jupiter’s moons
were orbiting Jupiter and not the Earth, which everything orbited
according to Ptolemy’s concentric model. If Jupiter could
retain its satellites, then the Earth could retain the moon as it
went around the sun. He published a paper about his findings and
got in trouble twice with the Roman Catholic Church which placed
him under house arrest until his death for advocating the
Copernican theory.
Newton
The science of astronomy still needed one more piece in its
foundation for others to build upon. This piece was contributed
by an English man named Sir Isaac Newton (1642-1727). Newton was
an astronomer, scientist, and mathematician who investigated the
laws of gravity and made spectacular discoveries about light. He
formulated laws which explained how objects move and how gravity
operates. He also laid the ground work for the study of spectrum
analysis. He also made the first reflecting telescope which made
possible the huge observatory telescopes of today.
The laws provided by Kepler, Galileo, and Newton were not
perfect but they had a good degree of reliability and were used
for many years. There have been revisions of their laws by Albert
Einstein and others but the original laws are still used by many
for calculations that do not need an extremely high degree of
precision.
Einstein
One of the most profound impacts on science were two theories
proposed by Albert Einstein. Albert Einstein (1879-1955) realized
that all motion was relative, that is, coordinates and the
descriptions of movements meant nothing unless the reference body
was defined. He also had evidence that the speed of light was a
constant, being the same speed no matter how fast an observer is
moving, which violates the Newtonian laws of motions but was
later demonstrated experimentally. In creating his theory, he
made the requirements that all defined laws must work with
respect to all bodies of reference and that the speed of light
with respect to all bodies was the same. To bring the
requirements into one theory, he used a set of mathematical
formulas called the Lorentz transformation. The Lorentz
transformation defined the formulas to use when converting
coordinates from one reference body to another when the first
body is moving at a constant speed with respect to the second.
With these formulas, he discovered that time and mass cannot be
constant for the speed of light to be constant; thus, time can
not be separated from space so the two must exist together in a
four dimensional space-time continuum. For instance, if two
trains are moving on two parallel tracks in the same direction at
different speeds toward a light source, and the speed of light
from the light source is the same for both of them, then time for
the faster train must be slightly slowed. In 1905, Einstein
published his findings in his Special Theory of Relativity. The
Special Theory of Relativity could only be used in the absence of
gravitational fields so he published his General Theory of
Relativity in 1916. The General Theory of Relativity basically
says that all matter curves space, and in turn, how space is
curved affects the movement of matter, which explains
gravitational fields. This theory is constantly being validated
by modern scientific experiments.
Space Exploration
The history of space exploration starts at about this time. In
1926, an American scientist named Robert H. Goddard built and
flew the first successful liquid propelled rocket. By 1930,
groups were being formed which experimented with rockets and by
the early 1940s, the United States and the Soviet Union were both
researching high altitude rockets.
The Space Race
During the cold war in the 1950s, both the United States and
the Soviet Union announced plans to launch earth-orbiting
satellites. This began what is called the "space race".
At first, Dwight Eisenhower, the president of the U.S. at the
time, was reluctant to get involved in the race because he
thought that an American satellite orbiting the earth above the
Soviet Union’s territory would be seen as a threat and start
a war.
At this time, the U.S. military had a high altitude rocket
called the Jupiter. On a missile test flight on September 20,
1956, the Jupiter rocket was flying over the South Atlantic when
its nose cone briefly went into space before arching down to the
ocean. The Jupiter’s designer and a few others knew that the
nose cone, if detached, could have gone fast enough to orbit the
earth. The Pentagon suspected that the Army might try to "accidentally"
put another Jupiter nose cone into orbit so they ordered the Army
to fill the nose cones with sand and to disable the Jupiter’s
fourth stage.
Sputnik 1 and Explorer
One year and 14 days later, on October 4, 1957, the Russians
put a small sphere with a radio transmitter into orbit, which was
the first manmade satellite to orbit the earth. They named this
small satellite Sputnik 1 and it prompted the Americans to put
their own satellite into orbit. On January 31, 1958, the American
satellite Explorer, which had some scientific equipment, was put
into orbit with a Jupiter C rocket. Explorer had been fitted with
a special Geiger counter from physicist James Van Allen which
recorded the previously unknown Van Allen belts of radiation
around earth.
Human Exploration
On January 20, 1961, John F. Kennedy became president and on
May 25 of that same year announced the goal of sending an
American to moon and bringing him back safely. To reach this goal,
he executed the Apollo program. Before humans could go to the
moon, however, humans needed to at least get into orbit. Before
humans went into orbit, each country used animals to test the
technology.
The Soviets were the first ones to send an animal into space.
In 1957, they sent a dog named Laika into orbit in a capsule
named Sputnik 2. She survived for a week before running out of
oxygen.
The Americans were next, on January 31, 1961, they shot a
chimpanzee named Ham in a Mercury capsule to an altitude of 157
miles. The chimp was recovered in good health.
That year, on April 12, the Soviet Yuri Gagarin was the first
person in space. The Americans followed on May 5 with Alan
Shepard being the first American in space. Gagarin’s flight
lasted 1 hour and 48 minutes and he was in orbit 89 minutes. His
highest altitude was 203 miles above the earth. Shepard’s
flight lasted 15 minutes and he rocketed to 117 miles above the
earth but did not make it to orbit.
On February 20 1962, John Glen became the first American to
orbit the earth. His trip lasted 4 hours and 55 minutes and he
orbited the earth three times. His highest altitude was 162.5
miles.
For years after that, the space race between the Soviets and
the Americans continued and many more people orbited the earth as
the technology progressed. The race finally ended on July 20,
1969 when Apollo 11 successfully landed on the moon and Americans
Neil Armstrong and Edwin Aldrin became the first humans to walk
on the moon. The United States sent a total of 12 men to the moon,
the last being Eugene Cernan on the Apollo 17 mission on December
14, 1972. No human has walked on the moon since. The Soviets
never made it to the moon.
Since then, many scientists have made discoveries and
developed the technology to look farther into the cosmos, but not
much could have happened without those first astronomers,
philosophers, and scientists taking time to look at our universe
for what it really was.
