PSc 100 Survey of Astronomy Associate Professor M

PSc 100 Survey of Astronomy Associate Professor M. Böttcher Clippinger Hall #339 Phone: 593 1714 E-mail: boettchm@ohio. edu Office Hours: Mo. , Tu. , We. , Th. , 3: 00 p. m. – 4: 00 p. m.

General Information • Course Web Site: http: //www. phy. ohiou. edu/~mboett/PSC 100/spring 12/PSC 100_spring 12. html Check this web site regularly. All lecture powerpoints, updates, reading assignments, exam results, etc. will be posted on this web site

The Turning. Point Response System • We will use the Turning. Point response system for questions + answers throughout the lectures (Mo. – We. ). • Class participation during regular lectures will be measured with the Turning. Point system (starting in the 2 nd week of classes) and enter with 10 % into the final class grade. • Turning. Point will also be used for 6 Reading Assignment Quizzes almost every Thursday. Scores of Reading Assignment Quizzes will be combined to 30 % of your final class grade. • If you do not have a Turning. Point clicker, please buy one from the Tech Depot on the ground floor of Baker Center. • Tech Depot staff will be available to toruble-shoot clickers (if necessary) and replace batteries for free.

As a Matter of Courtesy • Please turn your cell phones off or on vibrating mode during the lectures • If you really need to leave during the lecture, do so quietly, through the rear door of the lecture hall.

The Scale of the Cosmos • Astronomy deals with objects on a vast range of size scales and time scales. • Most of these size and time scales are way beyond our every-day experience. • Humans, the Earth, and even the solar system are tiny and unimportant on cosmic scales.

A Campus Scene 16 x 16 m

A City View 1 mile x 1 mile

The Landscape of Pennsylvania 100 miles x 100 miles

The Earth Diameter of the Earth: 12, 756 km

Guess: How many times would you have to travel around the Earth to travel the distance between the Earth and the moon? 1. 2. 3. 4. 5. 2. 1 9. 6 26 745 1. 38 million

Earth and Moon Distance Earth – Moon: 384, 000 km

Earth orbiting around the Sun Distance Sun – Earth = 150, 000 km

Earth orbiting around the Sun In order to avoid large numbers beyond our imagination, we introduce new units: 1 Astronomical Unit (AU) = Distance Sun – Earth = 150 million km

How many miles are there in 1 AU? 1. 2. 3. 4. 5. 245, 000 9. 4 million 93. 7 million 1. 38 billion 3. 6 trillion

The Solar System Approx. 100 AU

(Almost) Empty Space Around our Solar System Approx. 10, 000 AU

The Solar Neighborhood Approx. 17 light years

The Solar Neighborhood New distance scale: 1 light year (ly) = Distance traveled by light in 1 year = 63, 000 AU = 1013 km = 10, 000, 000 km (= 1 + 13 zeros) = 10 trillion km Nearest star to the Sun: Approx. 17 light years Proxima Centauri, at a distance of 4. 2 light years

1 AU (= 150 million = 150, 000 km) equals 1. 2. 3. 4. 5. 1. 5*108 km 1. 5*1010 km 1. 5*1015 km 8*101. 5 km

The Extended Solar Neighborhood Approx. 1, 700 light years

The Milky Way Galaxy Diameter of the Milky Way: ~ 75, 000 light years

The diameter of the Milky Way is 1. 2. 3. 4. 5. 7. 5*103 light years 7. 5*104 light years 7. 5*105 light years 5*107. 5 light years 57. 5 light years

The Local Group of Galaxies usually don’t exist alone, but in clusters of galaxies Distance to the nearest large galaxies: several million light years

The Universe on Very Large Scales Clusters of galaxies are grouped into superclusters. Superclusters form filaments and walls around voids.