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.
