Measuring the distance to stars using parallax

[alemsalem]

how can you use the angle to determine the distance if you don't know the motion of the star itself.
is it by observing the star from the same point in two different years and then subtracting off this effect?

 

[russ_watters]

Motion? That doesn't have anything to do with the distance. The difference in position provides you an angle and the diameter of Earth's orbit a measuring stick.

Try drawing a diagram.

 

[Drakkith]

Most stars do not move significantly over the course of 6 - 12 months. For those that do you can simply figure out the proper motion and correct for it to find the parallax.

 

[Chronos]

You are correct, asalem. The proper motion component is derived from multiple parallax measurements. It is, however, vanishingly small for most stars. See http://csep10.phys.utk.edu/astr162/lect/motion/proper.html.

 

[pmacias]

Yes, measuring the distance to stars using parallax involves observing the star from two different points on Earth's orbit around the Sun, which are approximately six months apart. This creates a baseline for measuring the parallax angle, which is the apparent shift in the star's position relative to more distant stars. By measuring this angle and knowing the baseline distance between the two observation points, we can use trigonometry to calculate the distance to the star.

The motion of the star itself does not need to be known in order to determine its distance using parallax. However, it is important to take into account any potential sources of error, such as the motion of the Earth's atmosphere, when making these measurements. This can be done by observing the star multiple times and averaging the measurements to minimize the effects of atmospheric distortion.

In summary, measuring the distance to stars using parallax is a reliable method that utilizes the principles of trigonometry and careful observation to accurately determine the distance to stars, even without knowing their motion.