How does parallax change as the distance to a star increases?

1 Answer
Dec 5, 2015

The parallax angle would decrease for stars that are farther away.


Astronomers use parallax to measure distance by looking at how stars appear to move against their background as the Earth orbits the sun. By measuring the parallax angle, #p#, astronomers can calculate how far away a star is using the parallax formula;


For the derivation of the parallax formula, click here . If we plug in smaller values of #p# the distance, #d#, will be larger. This should make sense if we picture how parallax works.

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You can even test this on your own by holding a finger up to your nose and closing one eye, then the other. Your finger will appear to move compared to the wall across from you. If you hold your finger out at arms length and repeat the experiment, how far does your finger appear to move?