Download Concise pioneers of astronomy

Giants of Astronomy
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Aristarchus 310-230 B.C. was certainly both a mathematician and astronomer and he is
most celebrated as the first to propose a sun-centered universe. He is also famed for his
pioneering attempt to determine the sizes and distances of the sun and moon. According
to his contemporary, Archimedes, Aristarchus was the first to propose not only a
heliocentric universe, but also one larger than any of the geocentric universes proposed
by his predecessors.
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Hipparchus was a Greek astronomer who lived between 190-120 B.C. He created the
first accurate star map and kept a catalogue of over 850 stars with their relative
brightness’s.
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Ptolemy Claudius Ptolemy (about 87-150) was a Greek astronomer and mathematician
who wrote about his belief that all celestial bodies revolved around the Earth. His
writings influenced people's ideas about the universe for over a thousand years, until the
Copernican System (with a heliocentric solar system) was accepted.
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Nicholas Copernicus was a Polish astronomer who lived between 1473-1543. Before
his time, people believed in the Ptolemaic model of the solar system, which maintained
that the Earth was the center of the universe. Copernicus changed this belief when he
introduced the heliocentric model, centered on the sun. He claimed that all the planets,
including Earth, moved in orbits around the sun, and showed how this new system could
accurately calculate the positions of the planets.
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Tycho Brahe was a Danish astronomer who lived between 1546-1601. For over twenty
years, he made very accurate observations of the night sky, all without the aid of a
telescope, which had not yet been invented. Tycho also built the world's first observatory
and kept a star catalogue with over 1000 stars. Tycho's records were used by Johan
Kepler to describe the orbits of planets around the sun and disprove the Ptolemaic
theory.
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Johannes Bayer (1564-1617) was a Bavarian (German) astronomer who first named
stars by assigning them to constellations and giving them Greek letters (alpha, beta,
gamma, delta, etc.), in magnitude classes (by decreasing brightness). Bayer published
Uranometria (a detailed star chart/catalog) in 1603.
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Hans Lippershey (1570?-1619) was a German-born Dutch lens maker who
demonstrated the first refracting telescope in 1608, made from two lenses; he applied for
a patent for this optical refracting telescope (using 2 lenses) in 1608, intending it for use
as a military device
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Galileo Galilei was an Italian astronomer and physicist who lived between 1564-1642.
He challenged Aristotle's proposition that heavenly bodies were divine and therefore
perfect and blemish-free. Galileo was the first person to use a telescope to look at the
heavens. He discovered sunspots, and craters and peaks in the moon. He discovered the
large moons of Jupiter, which have been named for him. Galileo's work offended the
Roman Catholic Church and he was sentenced to house arrest for the later years of his
life. Today, he is remembered as a martyr for scientific truth.
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Johan Kepler was a German astronomer who lived between 1571-1630. He introduced
three important laws of planetary motion and helped the Copernican model of the solar
system gain general acceptance. Kepler inherited Tycho Brahe's observational data on
Mars following Brahe's death and showed, mathematically, that Mars followed an
elliptical orbit. This new revelation contradicted the age-old belief that heavenly bodies
all moved in perfect circles. With Tycho Brahe's observations, Kepler set out to
determine if the paths of the planets could be described with a curve .
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Christian Huygens was a Dutch physicist and astronomer who lived between 16291695. He found new methods for grinding and polishing lenses, making telescopes more
powerful. Using a telescope he had made, Huygens first identified Saturn's rings and one
of Saturn's moons. Huygens also invented the pendulum clock, increasing the accuracy
of timekeeping, and proposed the wave theory of light.
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Isaac Newton was an English scientist and mathematician who lived between 16421727. He had one of the most brilliant minds the world has ever known. Legend has it
that seeing an apple fall gave Newton the idea that gravity, the force that keeps us bound
to the Earth, also controls the motion of planets and stars. Newton's contributions to
science include the universal law of gravitation, the development of a whole new field in
mathematics called calculus, and his famous three laws of motion.
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Ole Romer (1644-1710) was a Danish astronomer who, in 1675-1676, was the first
person to demonstrate that the speed of light is finite. Romer did this by observing
eclipses of Jupiter's moon Io as Jupiter’s distance from Earth varied through the year. He
noticed that the observed period of Io's orbit differed by about 20 minutes; he concluded
that this difference was due to the extra distance that the light had to travel to Earth.
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Edmond Halley was an English astronomer who lived between 1656-1742. Using
historical records, his own observations, and Newton’s universal law of gravitation, he
reasoned that the comets, which had appeared in 1456, 1531, 1607, and 1682, were one
and the same. He then predicted the comet’s return about every 76 years. Although
Halley died in 1742, the comet reappeared 16 years later, and today bears his name.
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William Herschel was born in Germany and lived in England as he worked as an
astronomer. He lived between 1738-1822. He built high magnification telescopes that let
him observe the heavens with greater detail. Herschel discovered the planet Uranus and
advanced our understanding of nebulae, the hazy clouds that surround dying stars. He
also founded stellar astronomy, the study of the region beyond our own solar system. Our
modern sense of a galaxy’s shape is very similar to what Herschel had proposed
hundreds of years earlier.
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Charles Messier (1730-1817) was a French astronomer who searched the skies for
comets. He compiled a list of 103 fuzzy objects (nébuleuse sans étoile, or starless
nebulosities) in space in order not to mistake star clusters, galaxies, and nebulae for
comets (for which he was searching). The Messier list has been added to and now
consisted of 35 galaxies, 30 open clusters, 29 globular clusters, 4 planetary nebulae, 7
diffuse nebulae, and two unconfirmed objects (which were mistaken for nebulae by
Messier).
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Christian Doppler was an Austrian mathematician who lived between 1803-1853. He is
known for the principle he first proposed in concerning the colored light of double stars
in 1842. This principle is now known as the Doppler effect. He hypothesized that the
pitch of a sound would change if the source of the sound were moving. He didn't test this
hypothesis until 1845. To test his hypothesis, Doppler used two sets of trumpeters: one
set stationary at a train station and one set moving on an open train car. Both sets of
musicians had perfect pitch and held the same note. As the train passed the station, it was
obvious that the frequency of the two notes didn't match, even though the musicians
were playing the same note. This proved Doppler's hypothesis.
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Albert Einstein was a German physicist who lived between 1879-1955. Probably the
most well known scientist of the twentieth century, Einstein came up with many original
theories and invented modern physics. He is most famous for his theory of relativity,
which makes bold statements about the nature of light and also shows the relationship
between mass and energy. Einstein's accurate predictions on the link between gravity
with space and time also made him a celebrity. His calculations predicted an expanding
universe and he described space/time.
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Henrietta Swan Leavitt was born in Massachusetts in 1868. She became interested in
astronomy in college. Unfortunately, she got sick after her graduation from college. She
did recover from her sickness, though it did leave her almost completely deaf. But she
hadn't forgotten astronomy! She observed stars and watched how variable stars changed
in brightness. Henrietta is known for her discovery of a type of variable stars named
Cepheid variables. Cepheid variables are stars that go through cycles of brightness and
darkness. Henrietta found that when observing a Cepheid variable, she could relate the
length of the brightness cycle to the size of the star. With this discovery, she was able to
determine the distances between stars and the Earth.
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KIRCHOFF, GUSTAV
Gustav Kirchoff (1824-1887) was a German physicist who realized that each element
gave off a characteristic color of light when heated to incandescence. When separated by
a prism, the light for each element had a specific pattern of wavelengths. Kirchoff,
together with Bunsen, used his techniques to discover two new elements, cesium (1860)
and rubidium (1861). Kirchoff found that when light shines through a gas, the gas
absorbs some of the light, the same wavelengths of light that it would emit when heated.
He applied his techniques to the Sun, explaining Fraunhofer lines.
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Edwin Hubble was an American astronomer who lived between 1889-1953. His
observations of galaxies helped him develop the idea of an expanding universe, which
forms the basis of modern cosmology, the study of the origin of the universe. He also
discovered a relationship between a galaxy’s speed and its distance. The Hubble space
telescope, currently on an observation project in space, bears his name.
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Karl G. Jansky (1905-1949) was an American radio engineer who pioneered and
developed radio astronomy. In 1932, he detected the first radio waves from a cosmic
source - in the central region of the Milky Way Galaxy.
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BELL, JOCELYN
Susan Jocelyn Bell Burnell (1943- ) is an astronomer who discovered the existence of
pulsars in 1967, while she was a graduate student at Cambridge University. A pulsar is a
rapidly spinning neutron star that emits energy in pulses. Bell's graduate advisor
(Anthony Hewish) was given a share of the 1974 Nobel Prize, but Bell was ignored. No
one had any idea what these unusual objects were at the time, so the name little green
men (LGM) was used. Soon, Thomas Gold suggested that pulsars were rapidly spinning
neutron stars, the remnants of a supernova.
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CHANDRASEKHAR, S.
Subrahmanyan Chandrasekhar (Born Lahore, India on Oct. 19, 1910 -Died Chicago,
USA in 1995) was an Indian-American astrophysicist who studied stellar physics,
evolution, and black holes. He realized that the fate of dying stars depended upon their
mass, and above a certain point (1.4 times the mass of the Sun, now known as the
"Chandrasekhar limit"), a star will undergo extreme collapse and not simply becomes a
white dwarf.
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SAGAN, CARL
Carl Sagan (1934-1996) was an American astronomer who discovered that the surface of
Venus was extraordinarily hot and noxious (contrary to previous models of a mild
Venusian surface). Sagan also showed that the universe has many organic (carbon-based)
chemicals and that life is likely to exist throughout the cosmos. He was a great
popularizer of astronomy, was involved in many NASA flights and SETI, and also
pioneered the field of exobiology.