Parallax is the change of the apparent position of the star in the sky as the earth revolves around the sun. It can be used to measure the distances of nearby stars from earth. The relationship between parallax and distance is reciprocal. Meaning, as the parallax angle increases, the distance of the star from the earth decreases. If a star has a large parallax angle, then that star is near to the earth. But this type of measuring stellar distances is only applicable for nearby stars because the earth’s telescopes have difficulty in measuring very small parallax angles accurately.