Parallax: Use in Measuring the Distance to Stars
Parallax refers to the apparent movement of a nearby star against the background of more distant stars, as the earth moves around the sun. Parallax is shown as half of the angle which a star appears to move, as the earth moves from one side to the other. Star distances are measures in units of the distance from the sun to the earth (called the Astronomical Unit). The nearer the stars, the longer is the angle called the parallax between the January and July observations.
In 1989, the European space agency launched Hipparcos (An acronym for High Precision Parallax Collecting Satellite) dedicated to the measurement of stellar parallax. The satellite was named after Hipparchus, a Greek astronomer famous for many observations of celestial objects. The data from the satellite formed the basis for an all-sky catalogue of one million stars up to the visual magnitude of 11.
To know how you can measure the distance between stars, watch the video below.