Where are we in the universe?

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

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

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

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

5. Our Cosmic Address SPaydirt Pete UTEP 500 W. University Ave. El Paso, TX 79968 USA Earth Solar System

6. Our Cosmic Address Paydirt Pete UTEP 500 W. University Ave. El Paso, TX 79968 USA Earth Solar System Milky Way Galaxy

7. Our Cosmic Address Paydirt Pete UTEP 500 W. University Ave. El Paso, TX 79968 USA Earth Solar System Milky Way Galaxy Local Group

8. Our Cosmic Address Paydirt Pete UTEP 500 W. University Ave. El Paso, TX 79968 USA Earth Solar System Milky Way Galaxy Local Group Local Supercluster

9. How do we know? Who is responsible?

10. 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 Aristarchus Eratosthenes Pythagoras Aristotle 500 250 0 250 1500 1600 1700 1800 1900 AD

11. • claimed that all planets & stars orbited • the Earth (wrong!) • • Earth-Centered model = Geocentric Model • • ideas last 1300 years! Ptolemy geocentric diagram (Earth at center) Ptoo bad for Ptolemey Claudius Ptolemey (100 - 170 A.D.) Aristarchus Eratosthenes Pythagoras Aristotle Ptolemy 500 250 0 250 1500 1600 1700 1800 1900

12. • proposed Earth NOT AT CENTER, but SUN IS! • Sun-Centered model = Heliocentric Model Copernicus heliocentric diagram (sun at center) Crazy (but not really) Copernicus Nicholas Copernicus (1473-1543) Aristarchus Eratosthenes Pythagoras Copernicus Aristotle Ptolemy 500 250 0 250 1500 1600 1700 1800 1900 AD

13. •Venus phases Galileo’s moon phases Galileo the Great Galileo Galilei (1564 - 1642 A.D.) • The Great Observer! • 1st to observe moons orbiting Jupiter (Galilean satellites)- proved geocentric model wrong Aristarchus Eratosthenes Pythagoras Copernicus Galileo Aristotle Ptolemy 500 250 0 250 1500 1600 1700 1800 1900 AD

14. • Used catalogs of planets’ positions to form equations that described all planetary motion Kepler’s Laws (3) Keeping up with Kepler Johannes Kepler (1571 - 1630 A.D.) Aristarchus Eratosthenes Kepler Pythagoras Copernicus Galileo Aristotle Ptolemy 500 250 0 250 1500 1600 1700 1800 1900 AD

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

16. C D close to sun A B far from sun travels fastest travels slowest time to go from C D = time to go from A B 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

17. Kepler’s Law #2 slow speed fast speed equal area, equal times

18. P = orbital period (years), time to complete 1 orbit a = orbital radius (AU, astronmomical unit) *note: 1 AU is distance from Earth to Sun, 1.5x108 km like lanes on a race track Kepler’s Law # 3 P2~ a3 orbital period orbital radius

19. Shoemakers Lowell Sagan Modern Astronomers • Percival Lowell (1855 - 1916 A.D.) - observed canals on Mars • 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 Aristarchus Eratosthenes Kepler Pythagoras Copernicus Galileo Aristotle Ptolemy 500 250 0 250 1500 1600 1700 1800 1900 AD

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

21. Ocean waves Sound waves Seismic waves a wave What is a wave? Waves are traveling energy

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

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

24. 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

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

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

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

28. Galaxy M81 The Moon visible radio visible radio 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

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

30. • Hubble Space Telescope • 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 Telescopes and Observatories (you should visit)