Here's how it works:

* The Principle: As the Earth orbits the Sun, our viewpoint shifts slightly. This means that nearby stars appear to move against the background of more distant stars. This apparent shift in position is called parallax.

* Measuring Distance: Astronomers measure the angle of this shift. The larger the angle, the closer the star. Using trigonometry, they can calculate the actual distance to the star.

Parallax is a fundamental technique in astronomy for determining distances to nearby stars. It forms the basis for measuring distances to more distant objects using a chain of measurements.