1. Lecture 2: Overview of the solar system: Background for discussion of Mars and Saturn
Mathematics in astronomy: the essence of physical sciences like astronomy is the mathematical structure of the universe. This is a Hellenistic idea.
A useful tool: scientific notation in expressing very large and very small numbers

2. Scientific Notation: A shorthand for expressing very large or very small numbers
1640 = 1.64 X 1000; 1000=10X10X10 = 103; = 1.64 X 103 , OR 1.64E+03.
6,280,000 = 6.28X1,000,000; 1,000,000=10X10X10X10X10X10 =106 ; 6,280,000 = 6.28X106 = 6.28E+06
Little numbers too; = 1.5/1000 = 1.5X(1/1000) = 1.5X(1/(10X10X10)) = 1.5X(1/103) = 1.5X10-3 =1.5E-03

3. An Overview of the Solar System

4. Size scales in the solar system
Basic unit: 1 meter
1 kilometer = 1000 meters = miles
Diameter of Earth: kilometers (~ LA to Sydney)
Closest object in space: Moon, 384,000 km average distance
Most prominent object is astronomy: Sun, million kilometers; 1 Astronomical Unit
demo

5. The Sun

6. Facts about the Sun
Distance: million kilometers = 1.496E+11 meters = 1 astronomical unit
Radius = 695,990 kilometers = 6.960E+08 meters (109 times radius of Earth)
If Earth were scaled to 1 foot globe size, the Sun would extend from goal line to 30 yard line at Kinnick stadium
The Sun, not the planets (including Earth) is the dominant object in the solar system

7. The Terrestrial Planets
Distance (au)
Size
Mercury
0.387
0.38
Venus
0.723
0.95
Earth
1.00
Mars
1.523
0.53

8. The Jovian Planets Planet Distance (au) Diameter Jupiter 5.2 11.2
Saturn
9.5
Uranus
19.2
4.0
Neptune
30.1
3.9

9. The Earth and Mars

10. But… the Earth and Saturn