Transcript Astronomy - PowerPoint

ASTRONOMY
Look to the Sky……Why?
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Astonomy is a Human Adventure – even if
you’ve never looked at the sky!
The development of astronomy is intertwined
with development of civilization
Revolutions in astronomy revolutionize the
science and technology that shape modern life
It’s really, really cool!
Dead Dudes of Astronomy
 Pythagoras (500 BC)
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Greek philosopher
Believed that circles and spheres were
“perfect” heavenly forms: thus the Earth must
be a sphere (since the Earth was “obviously” at
the center of the Universe).
Perfect “10”
Aristotle
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Greek Philosopher (300 BC)
Described evidence for spherical Earth:
Lunar eclipse always showed curved shadow of
Earth
 Altitude of North Star changes as we travel north,
suggesting Earth’s surface if curved
 As a ship sails over the horizon, we lose sight of the
hull before the sail.
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Ptolemy (140 AD)
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Created the Geocentric Model of the Earth
Earth was center of all motion
 Everything moved around Earth in circular orbits
(Model was accepted as official doctrine of Catholic
Church until the Renaissance)
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Hypatia (355?-415)
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Natural Philosopher in Alexandria, Egypt
Wrote books on Astronomy, Geometry, and
Philosophy
Developed ideas on conic sections, leading to
ideas of hyperbolas, parabolas, and ellipses
Hypatia came to symbolize learning and science
which early Christians identified with paganism
Copernicus (1473-1543)
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Polish doctor, lawyer, and amateur astronomer
Sought simpler model
Solution: Heliocentric – or sun-centered –
model, but the model lacked evidence
Published ideas on his deathbed
Galileo (1564-1642)
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DID NOT invent the telescope, just used it first
for astronomy!
Discovered moons of Jupiter
Observed imperfections on Moon’s surface
Discovered that the sun rotates by observing
sunspots
Convicted of heresy, went blind, died under
house arrest. Conviction overturned in 1992!!
Einstein (1879-1955)
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General Theory of Relativity = “shape” of
space is influenced by matter and energy in it,
and space is curved
Special Theory of Relativity = deals with how
light behaves in curved space, and establishes
that speed of light is a constant (300,000
km/second)
Carl Sagan (1934-1996)
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We are all “star stuff ”
Well known for putting scientific concepts into
everyday language for the public
Steven Hawking (1942-Present)
*Not so dead dude……
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Theoretical Physicist
worked on the basic laws which govern the universe
showed that Einstein's General Theory of Relativity
implied space and time would have a beginning in the
Big Bang and an end in black holes
Lucasian Professor of Mathmatics, Cambridge
University, a possition once held by Isaac Newton
EARTH’S COSMIC ADDRESS
Earth is the 3rd Planet
from the Sun
The sun is one of 100 Billion star systems in
the Milky Way
The Milky Way is one of 40 galaxies in the
Local Group,
The Local Group is part of the Local
SuperCluster, which is part of the Universe
Galaxies
A large group of stars, gas and dust held
together by gravity.
There are three main types of galaxies.
Lenticular
Elliptical
Spiral
**There are at least 80 billion galaxies in the
Universe!!!
Lenticular Galaxy
Spiral without spiral structure:
Elliptical Galaxy
Ellipsoidal shape – looks like a cosmic football!
Contain little or no interstellar matter
Spiral Galaxy
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Large flat disc with spiral arms and a bulge:
The Milky Way
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Spiral Galaxy
Our Sun is one of several billion stars in the
Milky Way.
Features of a Spiral Galaxy
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Disc – made up of mainly younger stars that are
1 million to 10 billion years old
Bulge – at the core, high density, tend to contain
very old (>10 billion years) red stars
Halo – surrounds the disc, made up of low
density old stars and dark matter
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Our Sun is in the Orian Arm of the Milky Way
2/3 of the way from center of the Milky Way
Closest Neighbor
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Andromeda Galaxy – much like Milky Way
2.2 million light years away and approaching us
at 670,000 miles an hour!