Size Scales

Some Length Conversions

1 inch = 0.0254 meter (m) = 2.54 centimeter (cm)
1 Angstrom = 10^-8 cm = 10^-10 m
100 cm = 1 m
1 mile (mi) = 1.6 km
1 light year (ly) = distance light travels in 1 year = 6x10¹² mi = 9.6x10¹² km
1 parsec = 3.1x10¹⁸ cm = 3.1x10¹³ km = 3.3 ly
1 Kilo parsec (Kpc) = 1,000 pc
1 Mega parsec (Mpc) = 1,000,000 pc

Typical Size Scales in Our Universe

• Planck Scale ===> < 10^-33 cm
• Nuclei ===> 10^-13 cm
• Atoms and Molecules ===> 10^-8 cm
• Dust ===> 10^-6 - 10^-5 cm
• People ===> 2 m
• Eugene ===> 15 km
• U.S. ===> 3,000 x 4,500 km
• Earth ===> 13,000 km in diameter
• Solar System ===> 12 billion km in diameter
• Milky Way Galaxy ===> 40,000 pc (~120,000 light years)
• Local Group ===> few Mpc
• Larger Cluster ===> several Mpc
• Great Wall ===> 100 Mpc
• Observable Universe ===> 3,000-6,000 Mpc (10-20 billion light years)