The document provides an overview of metric and scientific units used in astronomy, including prefixes, fundamental SI units of length, mass, and time. It lists several special units used to measure large astronomical distances and objects, such as astronomical units, light-years, and parsecs. It also gives examples of metric equivalents for units like years, kilograms, and seconds. Finally, it mentions two resources that demonstrate relative sizes of objects in the universe on a scale of powers of ten.

1. The Astronomy Picture of the Day

2. Astronomical Numbers

3. Outline
• The Metric System
• Scientific Notation
• Special Units
• Approximations

4. Some Metric Prefixes
Power of 10 Exp. Notation Metric Prefix Abbreviation
billion 109 giga G
million 106 mega M
thousand 103 kilo k
hundredth 10-2 centi c
thousandth 10-3 milli m
millionth 10-6 micro μ
billionth 10-9 nano n

5. Fundamental MKS Units
English
Quantity Metric Unit Abbreviation
Equivalent
Length meter m 3.28 feet
2.2 pounds
Mass kilogram kg
(of mass)
Time second sec (same)

6. Special Units
Quantity Special Unit Abbreviation Metric Equivalent
Earth’s radius R 6.37×106 m
Sun’s radius R 6.97×108 m
Length Astronomical Unit AU 1.50×1011 m
Light-year ly 9.46×1015 m
parsec pc 3.09×1016 m
Earth’s mass M 5.97×1024 kg
Mass
Sun’s mass M 1.99×1030 kg
Year yr 3.16×107 sec
Time
Sun’s lifetime t 3.16×1017 sec
Speed Speed of light (vacuum) c 3.00×108 m/sec
Acceleration Earth’s surface gravity g 9.81 m/sec2
Energy Kiloton of TNT kt 4.18×1012 J
Power Sun’s luminosity L 3.86×1026 W

7. Sizes of special units
& various objects in
the universe–
ranging from the
submicroscopic to the
astronomical on a
scale of powers of 10.

8. The Powers of Ten
• Tutorial (Java-based): http://
micro.magnet.fsu.edu/primer/java/
scienceopticsu/powersof10/
• "Simpsons" version: http://
www.cakeshop.tv/clientsection_site/
jk/BestSimpsonsCouchGag.mov