Finding distance to stars and other celestial bodies has been a challenge throughout the history of astronomy. Some methods go back a long way in history, such as the Greek astronomer Hipparchus (around 150 BC), who determined the distance to the Moon with a method we now call parallax.
Most methods used today, have been developed over the last two centuries and are the result of countless nights of systematic observations by many astronomers and what we could call, old-fashioned detective work to find relationships and physical properties that somehow relate to distance.
Basically these methods can be separated in two groups:
In this module we will discuss the most commonly used methods in each of these groups.