PSc 100Survey 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/PSC100/spring12/PSC100_spring12.html

Check this web site regularly.

All lecture powerpoints, updates, reading assignments, exam results, etc.

will be posted on this web site

Link

The TurningPoint Response System

• We will use the TurningPoint response system for questions + answers throughout the lectures (Mo. – We.).

• Class participation during regular lectures will be measured with the TurningPoint system (starting in the 2nd week of classes) and enter with 10 % into the final class grade.

• TurningPoint 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 TurningPoint 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.

16 x 16 m16 x 16 m

A Campus Scene

1 mile x 1 mile1 mile x 1 mile

A City View

100 miles x 100 miles100 miles x 100 miles

The Landscape of Pennsylvania

Diameter of the Earth: Diameter of the Earth: 12,756 km12,756 km

The Earth

Guess: How many times would you have to travel around the Earth to travel the distance

between the Earth and the moon?

1. 2.1

2. 9.6

3. 26

4. 745

5. 1.38 million

Distance Earth – Moon:Distance Earth – Moon: 384,000 km384,000 km

Earth and Moon

Distance Sun – Earth = 150,000,000 kmDistance Sun – Earth = 150,000,000 km

Earth orbiting around the Sun

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. 245,000

2. 9.4 million

3. 93.7 million

4. 1.38 billion

5. 3.6 trillion

Approx. 100 AUApprox. 100 AU

The Solar System

Approx. 10,000 AUApprox. 10,000 AU

(Almost) Empty Space Around our Solar System

Approx. 17 light yearsApprox. 17 light years

The Solar Neighborhood

The Solar NeighborhoodNew distance scale:

1 light year (ly) =

Distance traveled by light in 1 year

= 63,000 AU = 1013 km

= 10,000,000,000,000 km

(= 1 + 13 zeros)

= 10 trillion km

Nearest star to the Sun:

Proxima Centauri, at a distance of 4.2 light years

Approx. 17 light yearsApprox. 17 light years

1 AU (= 150 million = 150,000,000 km) equals

1. 1.5*108 km

2. 1.5*1010 km

3. 1.5*1015 km

4. 8*1015 km

5. 8*101.5 km

Approx. 1,700 light yearsApprox. 1,700 light years

The Extended Solar Neighborhood

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

The Milky Way Galaxy

The diameter of the Milky Way is

1. 7.5*103 light years

2. 7.5*104 light years

3. 7.5*105 light years

4. 5*107.5 light years

5. 57.5 light years

Distance to the nearest large galaxies:Distance to the nearest large galaxies: several million light yearsseveral million light years

The Local Group of GalaxiesGalaxies usually don’t exist alone, but inGalaxies usually don’t exist alone, but in clusters of galaxiesclusters of galaxies

Clusters of galaxies are grouped intoClusters of galaxies are grouped into superclusterssuperclusters..Superclusters formSuperclusters form filamentsfilaments and and wallswalls around around voidsvoids..

The Universe on Very Large Scales