How do they measure the distance to other stars?
Mostly the distances to stars are measured by parallax. The position of the star relative to distant reference stars is measured six months apart, so that the Earth is on opposite sides of its orbit around the Sun. Then it’s just simple trigonometry to calculate the distance to the star, knowing the diameter of the Earth’s orbit. The accuracy of the measurement of distance depends on the accuracy of the parallax angle, which was improved considerably with the use of the Hipparcos satellites.
