Numbers in Astronomy

Astronomy is a mathematical science. I’ve done my best to make the math in this course painless, interesting, and (dare I say it) fun. However, understanding a few key math concepts will greatly improve your enjoyment of this class and your understanding of the universe.
Explore Appendix C: Scientific Notation to learn how we will use scientific notation to deal with very large or very small numbers in astronomy. Don’t worry about the “exercises” at the end. I’m not asking you to complete those.
Read Appendix D: Units Used in Science for an explanation of the metric units we will use to describe size, mass, and temperature of celestial objects.
An important unit of measure in astronomy is the “light-year.” Watch this nice demonstration from NASA, which illustrates how we can use light travel time to measure large distances in space.
Review 1.4 Numbers in Astronomy for a summary of all that we have learned so far in this lesson.
Light is really, really fast, but not infinitely fast. One amazing consequence of a finite speed of light is that looking up in the night sky allows us to look back in time. Watch the video Lookback Time to understand just how incredible this really is.
Finally, read 1.5 Consequences of Light Travel Time to see how our book describes the benefits of lookback time.