The main aim of this lesson is to show students that distances may be determined without a meter stick-a concept fundamental to such measurements in astronomy. It introduces students to the main concepts behind the first rung of what...

When describing distances in the solar system, it can be cumbersome to use common units of length, such as kilometers or miles. Instead, scientists use astronomical units to make the numbers more manageable. Watch this video description...

Defines the word 'parsec,' which is a unit of distance in space, and explains its origin. Also demonstrates examples where this unit of measurement would be used.

A video discussing how astronomers use how the Earth revolves around the sun and a nearby star's apparent movement as compared to more distant stars to possibly measure distance. [7:22]

This explanation is a follow-up to a video on stellar parallax that answers a question about angles. [2:21]

Sal Khan explains how to use parallax to figure out the distance of close stars. [9:26]

Sal Khan uses trigonometry to measure angles in the night sky to figure out how far we are from the nearest stars. [11:40]