How do astronomers measure the distance to a nearby star

astronomers can measure a star's position once, and then again 6 months later and calculate the apparent change in position. the star's apparent motion is called stellar parallax. the distance d is measured in parsecs and the parallax angle p is measured in arcseconds.                                                                                              

hope this : p

what experimental evidence led scientists to change from the previous model to this one?

a few of the positive particles aimed at a gold foil seemed to bounce back.

the colors of light emitted from heated atoms had very specific energies.

experiments with water vapor showed that elements combine in specific proportions.

cathode rays were bent in the same way whenever a magnet was brought near them.