1. The Size of Space

2. Relative Size Which ratio is bigger? A. The NIU campus compared to me.
B. The earth compared to DeKalb.
C. Our galaxy compared to the solar system.
D. The universe compared to our galaxy.

3. Length The oldest standards of length were based on the human body.
The metric system defined the meter in terms of the Earth: 1/10,000,000 from the pole to the equator.
The meter is now defined in terms of the second and speed of light.
The SI unit of length is the meter (m)

4. People-sized Spaces Me: Lecture Hall: Faraday West: NIU Campus:
5’9” = 1.75 m = 2 x 100 m
Lecture Hall:
14 m = 1 x 101 m
Faraday West:
80 m = 0.8 x 102 m
NIU Campus:
2400 m = 2 x 103 m
New Zealand Digital Library

5. Map-sized Spaces NIU campus: DeKalb county: Illinois: United States:
2400 m = 2 km = 2 x 103 m
DeKalb county:
29,000 m = 30 km = 3 x 104 m
Illinois:
338 km = 3 x 105 m
United States:
5000 km = 5 x 106 m
mapquest

6. Astronomical Unit Earth’s diameter: 13,000 km = 1 x 107 m
Earth to the Moon: 384,000 km = 4 x 108 m
Earth to the Sun: 150,000,000 km = 1.5 x 1011 m = 1 AU
The astronomical unit (AU) is the average distance from the earth to the sun.

7. Planetary-sized Spaces
Sun to the Earth:
1 AU = 1.5 x 1011 m
Sun to Saturn:
9.58 AU = 1.4 x 1012 m
Solar System (heliopause):
121 AU = 1.8 x 1013 m

8. Light Year
How long does it take light to go from the Sun to the Earth?
The speed of light is 3.0 x 108 m/s
How far does light travel in one year?
(1.5 x 1011 m) / (3.0 x 108 m/s) / (60 s/min)
= 8.3 minutes
(3.0 x 108 m/s) x (3.1 x 107 s)
= 9.46 x 1015 m = 63,240 AU
This equals one light year (ly)

9. Space-sized Spaces Sun to nearest star:
300,000 AU = 4.3 ly = 4 x 1016 m
Diameter of Milky Way:
110 kly = 1 x 1021 m
Diameter of Local Group
10 Mly = 1 x 1023 m
Diameter of Virgo Supercluster
110 Mly = 1 x 1024 m
Extent of the observable universe:
36 Gly = 3 x 1026 m

10. How big? A. NIU campus compared to me. (103)
B. The earth compared to NIU. (104)
C. Our galaxy compared to the solar system. (108)
D. Universe compared to our galaxy. (105)