Distances to Stars

It is crucial to be able to measure the distances to stars if we are to derive intrinsic luminosities. There are several methods for measuring distances to stars, but the most reliable by far (when it can be applied) is Trigonometric Parallax.

Hold a finger up in front of your nose, close one eye and note where the finger appears on the back wall. Now close the other eye (and open the one that was closed before) and note that the finger appears to move on the back wall. This is the parallax effect - the apparent motion of a nearby object compared to distance background objects because the change in viewing angle.


The asterick is a nearby star which is apparently moving back and forth every year compared to the more distance background stars. Note the star at the lower right which has a proper motion.

Michael Bolte
Mon Jan 26 12:32:25 PST 1998