CAPSTONE Astronomy
lecture 1, 07.06.2010
Course introduction, models of the
sky
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Lect. 1: Large and ancient questions
• Our view of the Universe has undergone
extensive change and quantification since the
beginnings of recorded science, in the days of
the Greeks. Obviously, the Universe is made
of stars.
• Are they all painted, as it were, on the vault
of heaven or are they dispersed through a
boundless Universe?
• Is the Universe made of irreducible atoms,
separated by a vacuum, or is matter a
plenum, a continuous string of connected
material?
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•Where is the center of the Universe?
•Are astronomical objects perfect, or physically
like Earth, full of asymmetries?
•Is the Universe described by equations, such
that knowledge is obtained by quantitative
study?
•Or can the nature of things be qualitatively
discovered?
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Size and age of Universe
I like to think of the growth in the perceived size of the
Universe in terms of money.
Aristotle’s Universe: 0.003 astronomical units, $0.03.
Copernican Universe: 20 AU,
$200.
Kant’s Universe: 100 Mpc (2x1013 AU), $20,000,000.
Einstein’s Universe: 3000 Mpc, or $600,000,000.
The volume of Kant’s Universe was 1036 times larger than that
of Copernicus. It is easy to understand that the possibilities
of strange things is much greater in the former case. Science
fiction writers could, and did, expand their horizons, as well.
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Age of the Universe
• With the realization that the Universe was so big, and
that light travels at a finite speed, the age of the
Universe had to be much greater than what was
previously thought. As shown by the quote at the end
of the lecture*, our modern idea of time is world’s
apart from the mainstream view up to 1800.
• Bishop Ussher: 1825, ~6000 years.
• Darwin:1859, 600,000,000 years (withdrawn after first
edition of OS).
• Kelvin, 1850: 30,000,000 years (based on erroneous
model of Earth.)
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• The discovery of radioactivity in 1896 provided a source
of heat for the Earth, so a longer time was thought
possible.
• By 1926, the estimated age of the Earth was
5,000,000,000 years (and the Universe had to be older).
• We now think the Universe as a whole is about
14,000,000,000 years old.
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The world systems
• Aristotle 300 B.C.
• Ptolemy 150 AD
• http://www.youtube.com/watch?v=FHSWVLwbb
Nw&feature=related
• Copernican (posthumous)
• Tychonian (to save appearances, data, and Bible)
• Kepler (geometric) (first real cosmology)
• http://www.youtube.com/watch?v=wGjlT3XHb9
A&feature=related
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Lipperhey
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Story of Liepperhey—1608.
Murano glass (still sold), Midleberg
VERY first could have been 1585 to 1608
Patent denied. Main interest was in
implements of war (Holland and Spain)
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Stopped down Galilean telescope
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Galileo’s discoveries
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Craters on moon
Sunspots
Many more stars in Milky Way than seen by eye
Moons of Jupiter
Dog ears on Saturn
Phases of Venus
Needed parallax to prove his system over Tychonian.
Stars get smaller as one uses larger telescopes (stars were fa
away, contrary to Tycho’s opinion that he could resolve stars
and they were nearby, hence should show parallax)
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Tycho’s system
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• An illustration in Yuanjing shuo (1626) explaining the phases of
Venus. Venus is shown as circling the Sun while the Sun moves
around the earth. (Sun Xiaochun, IHST, CAS, Beijing).
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Riccioli 1650 Tychonian and
Copernican system in the balance
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Caption for Riccioli drawing
• Detail from the frontispiece of Giovanni Battista
Riccioli’s Almagestum novum (Bologna, 1651).
The slogan by the discarded Ptolemy proclaims,
“I am raised up by being corrected.” As a Jesuit,
Riccioli gave precedence to his own Tychonic-type
system, which is more weighty in Urania’s balance
than the Copernican system. Note the telescope
in the hand of the observer, hundred-eyed Argus.
(Collection of Owen Gingerich)
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Result in 1650
• Phases of Venus wiped out Ptolemaic universe
• Galileo knew Copernicus was right and Kepler
agreed, but they could not criticize the
Tychonic system
• Jesuits demanded Tychonic as not being
unscriptural, as opposed to Copernicus.
• Accidental discovery of aberration of starlight in
1738 affirmed motion of Earth around the Sun.
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RESOLUTION
• Galileo’s discoveries dissolved the perfect
Universe of Aristotle.
• Accidental discovery of aberration of starlight in
1738 affirmed motion of Earth around the Sun.
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FURTHER RESOLUTION
• Successful recovery of Comet Halley affirmed that
Newton’s physics was useful and had meaning.(circa
1756)
• Parallax found in 1838 removed all doubt.
• Absence of parallax and thought that he could
resolve stars with his eye (stars were very close) kept
Tychonian system alive
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Literature (books you may know and when written)
aligned with science discoveries.
• The Tao Te Ching (a timeless work of Chinese spiritual
philosophy, by Lao Tse, born ca. 570 B. C.) was written in the
time of Pythagoras. (Xian, Da Qin, Forest of Stone Steles,
arrival of Chrisitanity in China, 638AD, “Light” ).
• Aristophanes' comedy, Clouds (423 B. C.) was written in the
time of Democritus, as was Oedipus Rex (after 431 B. C.) by
Sophocles.
• The apocryphal book of Judith was written near the time of
the poem of Lucretius that records the ideas of Democritus.
Machiavelli's The Prince was written in 1513, just before the
work of Copernicus.
• Shakespeare wrote Hamlet around 1600-1601, before Kepler
developed the laws of planetary motion and at the time that
Bruno was killed for advocating the atomist views.
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CAPSTONE 2010.Lecture 1
Literature
• John Milton wrote Paradise Lost in 1667, 25 years after the
nearly coincident death of Galileo and birth of Newton.
• Milton traveled to Italy and met Galileo in 1638.
• Robinson Crusoe was written by Daniel Defoe (1659?-1731) in
1719, near the time of Newton's death.
• Candide was written in 1759 by Voltaire (1694-1778), a
champion of science.
• Gulliver's Travels was published in 1729, just after Newton
died and Kant was born (by Jonathan Swift, 1667-1745).
• Oliver Twist by Charles Dickens (1812-1870) was written in
1838, the year Bessel succeeded in measuring the first
parallax, of the star 61 Cygni.
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