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Very Large Array (VLA)Soccoro, NM

Class 3: Astronomy 101Class 3: Astronomy 101

Where are we in the universe?

Planet?

Star-orbiting system?

Galaxy?

Cluster Group?

Supercluster?

Universe?

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Our Cosmic Address

Our Cosmic Address

Our Cosmic Address

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Our Cosmic Address

Our Cosmic Address

Our Cosmic Address

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Our Cosmic Address

How do we know? Who is responsible?

Early Astronomers

• 500 BC Pythagoras - thought Earth was round from moon observations

• 350 BC Aristotle - Earth at center of “universe”, planets/stars moved around Earth

• 250 BC Aristarchus - measured (relative) distance to Sun & moon using angles; Sun very BIG; at center of “universe”

• 200 BC Eratosthenes - measured size of the Earth using angles of sun at noon at 2 places

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PythagorasAristotle

Aristarchus Eratosthenes

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Ptoo bad for Ptolemey

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PythagorasAristotle

Aristarchus Eratosthenes Ptolemy

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Crazy (but not really) Copernicus

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PythagorasAristotle

Aristarchus Eratosthenes Ptolemy Copernicus

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Galileo the Great

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PythagorasAristotle

Aristarchus Eratosthenes Ptolemy Copernicus Galileo

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Keeping up with Kepler

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PythagorasAristotle

Aristarchus Eratosthenes Ptolemy Copernicus Galileo

Kepler

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Kepler Law # 1

Planets orbit the Sun in ellipses with Sun at one focus

circle ellipse focus

xxx xx

time to go from C D = time to go from A B

Kepler Law # 2

C Dclosest to suntravels fastest

A Bfurthest from suntravels slowest

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Kepler Law # 3

orbital period orbital radius

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• Percival Lowell (1855 - 1916 A.D.) - observed canals on Mars

Modern Astronomers

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PythagorasAristotle

Aristarchus Eratosthenes Ptolemy Copernicus Galileo

Kepler

• Carl Sagan (1934 - 1996 A.D.) - discovered hot, dense atmosphere on Venus - lead many searches for extra-terrestrial life

• Eugene & Carolyn Shoemaker - Eugene: linked Earth and moon craters to asteroid impacts - Carolyn: discovered more comets (32) than any other person

Lowell SaganShoemakers

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What is a wave?

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Light (electromagnetic) waves

medium waves = visible

Light (electromagnetic) waves

Tools of Astronomy(telescopes)

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Main functions of optical telescopes?

Radio Telescopes

light in

What do radio telescopes do?

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Where should they go?

Telescopes and Observatories(you should visit)