Post on 29-Jan-2016
transcript
Ast 1001 -- 1 Nov 2007
HOW DID THE PLANETS FORM ?
( Before about 1700 this would have been an idle question – not enough was known about physics and chemistry.)
Ast 1001 -- 1 Nov 2007
FACTS TO EXPLAIN
-- Nearly circular orbits, same plane -- Move in same direction -- Spacing of the orbits, distr. of mass -- Most planets rotate same direction -- Terrestrial vs. gas-giant planets -- Gas-giants have moons -- Asteroid belt -- etc.
Ast 1001 -- 1 Nov 2007
NEWTONIAN ORBITS, 1700:
“Calculate backward in time” ???
Ast 1001 -- 1 Nov 2007
GEORGES-LOUIS LECLERC DE BUFFON,1707—1788
-- Naturalist
-- Precursor to evolution theory -- Non-biblical history of Earth (Earth 75,000 years old?)
Movie trivia:
Jefferson in Paris (1995)
Brotherhood of the Wolf (2001)
Ast 1001 -- 1 Nov 2007
Comte de Buffon’s theory (c. 1770): tidal forces
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IMMANUEL KANT1724—1804
German (Prussian)
philosopher
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PIERRE SIMON DE LAPLACE1749—1827
-- Famous mathematician
and physicist-- Mechanique Celeste-- Theory of probability-- Minister of the Interior (but later turned against Napoleon)-- etc.
Ast 1001 -- 1 Nov 2007
LAPLACE 1796: Exposition du System du Monde ( a book for ordinary people! )
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“NEBULAE”: mysterious glowing clouds in space
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KANT AND LAPLACE SUGGESTED THAT NEBULAE WERE PLANETARY SYSTEMS BEING FORMED:
“THE NEBULAR HYPOTHESIS”
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Buffon proposed a “catastrophic” theory; but
The nebular hypothesis was an “evolutionary” theory.
( explain )
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Buffon proposed a “catastrophic” theory;
The nebular hypothesis was an “evolutionary” theory.
The practical difference is enormous.
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AGE OF THE EARTH (AND THE SOLAR SYSTEM)
Ast 1001 -- 1 Nov 2007
AGE OF THE EARTH (AND THE SOLAR SYSTEM)
c. 1750, The Bible: maybe 6000 years (depending on who was interpreting it)
Ast 1001 -- 1 Nov 2007
AGE OF THE EARTH (AND THE SOLAR SYSTEM)
c. 1750, The Bible: maybe 6000 years (depending on who was interpreting it)
1770, Buffon, cooling of the Earth: 75,000 years
Ast 1001 -- 1 Nov 2007
AGE OF THE EARTH (AND THE SOLAR SYSTEM)
c. 1750, The Bible: maybe 6000 years (depending on who was interpreting it)
1770, Buffon, cooling of the Earth: 75,000 years
1850, fossils: millions of years?
Ast 1001 -- 1 Nov 2007
AGE OF THE EARTH (AND THE SOLAR SYSTEM)
c. 1750, The Bible: maybe 6000 years (depending on who was interpreting it)
1770, Buffon, cooling of the Earth: 75,000 years
1850, fossils: millions of years?
1880, salt in ocean: even older?
Ast 1001 -- 1 Nov 2007
AGE OF THE EARTH (AND THE SOLAR SYSTEM)
c. 1750, The Bible: maybe 6000 years (depending on who was interpreting it)
1770, Buffon, cooling of the Earth: 75,000 years
1850, fossils: millions of years?
1880, salt in ocean: even older?
1890, Kelvin, cooling of both the Earth and the Sun: 30—100 million years
Ast 1001 -- 1 Nov 2007
AGE OF THE EARTH (AND THE SOLAR SYSTEM)
c. 1750, The Bible: maybe 6000 years (depending on who was interpreting it)
1770, Buffon, cooling of the Earth: 75,000 years
1850, fossils: millions of years?
1880, salt in ocean: even older?
1890, Kelvin, cooling of both the Earth and the Sun: 30—100 million years
1910, RADIOACTIVITY: billions of years!
Ast 1001 -- 1 Nov 2007
RADIOACTIVE DATING OF METEORITES: THE SOLAR SYSTEM IS 4.6 – 4.7 BILLION YEARS OLD.
( 4.65 x 10 9 = 4,650,000,000 years )
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EARLY ATMOSPHERE DIDN’T HAVE MUCH O 2 .
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NEXT: THINGS THAT GO BOOMP IN THE NIGHT
COSMIC IMPACTS
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IMPACT CRATERS ON THE MOON, MARS, MERCURY
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... AND SMALLER METEOROIDS, OF COURSE.
( ALL SIZES )
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FLASHES SEEN ON MOON! (?)
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NE Arizona, 50,000 years old
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Australia, 300,000 years old
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Northern Quebec, 1 million years
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Northern Canada,200 million years old
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GEOLOGISTS’ K-T BOUNDARY, 65 MILLION YEARS AGO
(“CRETACEOUS – TERTIARY”)
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GEOLOGISTS’ K-T BOUNDARY, 65 MILLION YEARS AGO
(“CRETACEOUS – TERTIARY”)
DINOSAURS R.I.P.
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IRIDIUM-RICH LAYER IN ROCKS
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SO WHAT?
WHY IS IRIDIUM IMPORTANT?
( explain )
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THE CHICXULUB EVENT,
65 MILLION YEARS AGO
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EFFECTS OF A BIG IMPACT
-- BLAST WAVE IN THE AIR
-- SEISMIC (earthquake)
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EFFECTS OF A BIG IMPACT
-- SEISMIC (earthquake)
-- TSUNAMI (see picture)
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EFFECTS OF A BIG IMPACT
-- SEISMIC (earthquake)
-- TSUNAMI (see picture)
-- PLANETARY CONFLAGRATION
Ast 1001 -- 1 Nov 2007
EFFECTS OF A BIG IMPACT
-- SEISMIC (earthquake)
-- TSUNAMI (see picture)
-- PLANETARY CONFLAGRATION
-- LONG LONG WINTER
Ast 1001 -- 1 Nov 2007
EFFECTS OF A BIG IMPACT
-- SEISMIC (earthquake)
-- TSUNAMI (see picture)
-- PLANETARY CONFLAGRATION
-- LONG LONG WINTER
---- ALTOGETHER, BIBLICAL IN SCOPE. ----
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ASTEROIDS
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COMET NUCLEUS
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MENTION HOW TO ESTIMATE
FREQUENCY OF EVENTS
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SIBERIA 1908: THE TUNGUSKA EVENT
PHOTO TAKEN 20 YEARS LATER
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Vela satellite Sept. 1979: a mystery
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