Where are we in the universe? Planet? Star-orbiting system? Galaxy? Cluster Group? Supercluster? Universe?

Our Cosmic Address Paydirt Pete UTEP 500 W. University Ave. El Paso, TX 79968

Paydirt Pete UTEP 500 W. University Ave. El Paso, TX USA Our Cosmic Address

Paydirt Pete UTEP 500 W. University Ave. El Paso, TX USA Earth Our Cosmic Address

SPaydirt Pete UTEP 500 W. University Ave. El Paso, TX USA Earth Solar System Our Cosmic Address

Paydirt Pete UTEP 500 W. University Ave. El Paso, TX USA Earth Solar System Milky Way Galaxy Our Cosmic Address

Paydirt Pete UTEP 500 W. University Ave. El Paso, TX USA Earth Solar System Milky Way Galaxy Local Group Our Cosmic Address

Paydirt Pete UTEP 500 W. University Ave. El Paso, TX USA Earth Solar System Milky Way Galaxy Local Group Local Supercluster Our Cosmic Address

How do we know? Who is responsible? 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 AD Pythagoras Aristotle Aristarchus Eratosthenes

Ptoo bad for Ptolemey Claudius Ptolemey ( A.D.) Pythagoras Aristotle Aristarchus Eratosthenes Ptolemy Ptolemy geocentric diagram (Earth at center) claimed that all planets & stars orbited the Earth (wrong!) Earth-Centered model = Geocentric Model ideas last 1300 years!

Nicholas Copernicus ( ) Crazy (but not really) Copernicus AD Pythagoras Aristotle Aristarchus Eratosthenes Ptolemy Copernicus Copernicus heliocentric diagram (sun at center) proposed Earth NOT AT CENTER, but SUN IS! Sun-Centered model = Heliocentric Model

Galileo the Great Galileo Galilei ( A.D.) AD Pythagoras Aristotle Aristarchus Eratosthenes Ptolemy CopernicusGalileo The Great Observer! 1st to observe moons orbiting Jupiter (Galilean satellites) - proved geocentric model wrong Galileo’s moon phases Venus phases

Keeping up with Kepler Johannes Kepler ( A.D.) AD Pythagoras Aristotle Aristarchus Eratosthenes Ptolemy CopernicusGalileo Kepler Kepler’s Laws (3) Used catalogs of planets’ positions to form equations that described all planetary motion

Kepler’s Law # 1 Planets orbit the Sun in ellipses with Sun at one focus focus x x circle ellipse xx x

Kepler’s Law # 2 A line joining a planet to the Sun sweeps out equal areas in equal times as the planet travels around the ellipse C D close to sun A B far from sun time to go from C D = time to go from A B travels slowesttravels fastest

Kepler’s Law #2 equal area, equal times fast speed slow spee d

P 2 ~ a 3 Kepler’s Law # 3 orbital period orbital radius P = orbital period (years), time to complete 1 orbit a = orbital radius (AU, astronmomical unit) *note: 1 AU is distance from Earth to Sun, 1.5x10 8 km like lanes on a race track

Percival Lowell ( A.D.) - observed canals on Mars Modern Astronomers AD Pythagoras Aristotle Aristarchus Eratosthenes Ptolemy CopernicusGalileo Kepler Carl Sagan ( 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 LowellSagan Shoemakers

We use electromagnetic waves (or light) (or radiation) How do we know? Who is responsible? Who is responsible?

What is a wave? Ocean waves Sound wavesSeismic waves Waves are traveling energy a wave

Light (electromagnetic) waves medium waves = visible BIG wavelengths small wavelengths

Light (electromagnetic) waves infrared image visible image x-ray image

Tools of Astronomy (telescopes) Objective - telescopes collect light (all kinds) Types - optical telescopes (for visible waves) - radio telescopes (for radio waves) - plus many others (x-ray, gamma, etc.) Determining factor: the bigger aperture (size), the better

Optical Telescopes Two types: Reflecting & Refracting Reflecting: uses a curved mirror to reflect & focus light (more common) light in eyepiece mirror Refracting: uses a lense (like eye-glasses) to focus light eyepiece light in lense

Main functions of optical telescopes? Sharpen images (resolving power) Make things look larger? Make objects look brighter (light-gathering power) yes, but….

Radio Telescopes Radio waves collected in large dish and reflected to center antenna light in

What do radio telescopes do? Detect radio waves emitted by space objects Allow us to “see” different properties of space that are invisible to us - temperature, magnetic field, composition The Moon visibleradio Galaxy M81 visibleradio

Where should they go? Problem: Earth’s atmosphere blurs objects in the sky how about a mountain top? in space? Ideal locations: Places away from city lights & pollution Places high in elevation US light pollutionMauna Kea, Hawaii

Hubble Space Telescope Telescopes and Observatories (you should visit) Hubble Space Telescope Keck: Mauna Kea, Hi Hubble Space Telescope Keck: Mauna Kea, Hi Hale: Palomar Obs., CA Hubble Space Telescope Keck: Mauna Kea, Hi Hale: Palomar Obs., CA Clark: Lowell Obs., AZ Hubble Space Telescope Keck: Mauna Kea, Hi Hale: Palomar Obs., CA Clark: Lowell Obs., AZ Shane: Lick Obs., CA Hubble Space Telescope Keck: Mauna Kea, Hi Hale: Palomar Obs., CA Clark: Lowell Obs., AZ Shane: Lick Obs., CA Kitt Peak Obs., AZ Hubble Space Telescope Keck: Mauna Kea, Hi Hale: Palomar Obs., CA Clark: Lowell Obs., AZ Shane: Lick Obs., CA Kitt Peak Obs., AZ Aricebo, Puerto Rico Hubble Space Telescope Keck (et al.): Mauna Kea, Hi Hale: Palomar Obs., CA Clark: Lowell Obs., AZ Shane: Lick Obs., CA Kitt Peak Obs., AZ Aricebo, Puerto Rico Very Large Array (VLA), NM