stellar parallax

Stellar parallax is a method used in astronomy to measure the distance to nearby stars. It relies on geometry, similar to how our two eyes allow us to perceive depth. As Earth orbits the Sun, our viewpoint shifts. This shift causes nearby stars to appear to move slightly against the backdrop of more distant, seemingly fixed stars. This apparent shift is called parallax.12

The angle of this shift, known as the parallax angle, is measured. Using the radius of Earth's orbit as a baseline, astronomers can calculate the distance to the star. The larger the parallax angle, the closer the star. A star with a parallax of one arc second is defined as being one parsec away, which is equivalent to 3.26 light-years. This method is most effective for stars within a few thousand light-years.342