Parallax

Click on the Parallax simulator

This simulation is to acquaint you with the concepts of parallax.

Set the Earth's orbit to 1 AU and click on space telescope. Change the distance to the star.

  1. How does the parallax angle change with distance?

  2. Now set distance to some fixed value. Change the orbital radius of the Earth. How are parallax angle and orbital radius related?

  3. Now set the simulation to research telescope which simulates a large ground based telescope. How does it differ from the space telescope for the same settings? Try this for the home telescope setting as well. Why is it difficult to measure parallax angles from the ground? Think about the following: The closest star to us is Proxima centauri, lying 1.3parsecs away. On a good night of observing, the atmosphere will allow an observer to measure stellar position to within +/- 1/2".

  4. What would be a consequence of astronomers not ever being able to measure accurate distances to stars?

  5. What are the distances for the following parallax angles (they are written in arcseconds) in parsecs?

    a) .001"

    b) .08"

    c) .25"

    d) 1/20"