Transcript PowerPoint File - University of Iowa Astronomy and Astrophysics

Lecture 2: Overview of the solar
system: Background for
discussion of Mars
• 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
Scientific Notation: A shorthand for
expressing very large or very small
numbers
• 1640 = 1.64 X 1000; 1000=10X10X10 =
103; 1640 = 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; 0.0015 = 1.5/1000 =
1.5X(1/1000) = 1.5X(1/(10X10X10)) =
1.5X(1/103) = 1.5X10-3 =1.5E-03
An Overview of the Solar System
Size scales in the solar system
demo
• Basic unit: 1 meter
• 1 kilometer = 1000 meters = 0.6214 miles
• Diameter of Earth: 12756 kilometers (~ LA to
Sydney)
• Closest object in space: Moon, 384,000 km
average distance
• Most prominent object is astronomy: Sun, 149.6
million kilometers; 1 Astronomical Unit
The Sun
Facts about the Sun
• Distance: 149.6 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
The Terrestrial Planets
Planet
Size
Mercury
Distance
(au)
0.387
Venus
0.723
0.95
Earth
1.00
1.00
Mars
1.523
0.53
0.38
The Jovian Planets
Planet
Diameter
Jupiter
Distance
(au)
5.2
Saturn
9.5
9.5
Uranus
19.2
4.0
Neptune
30.1
3.9
11.2
The Earth and Mars