What does the term "stellar parallax" indicate?

Stellar parallax refers to the apparent displacement of a nearby star against the background of more distant stars as observed from different positions in Earth's orbit around the Sun. This phenomenon occurs because as Earth moves, the angle from which we view the nearby star changes, creating a shift in its position relative to distant stars. The amount of this shift, measured in arcseconds, can be used to calculate the distance to the star using simple trigonometry.

This principle is fundamental in astronomy for measuring distances to stars within our galaxy, particularly those that are relatively close to Earth. As such, it provides crucial insights into the scale of the universe. It does not measure a star's brightness, rotational speed, or the distance between celestial bodies directly but rather serves as a method to determine the distance to stars based on their position changes as Earth orbits.