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Astronomy

How Astronomers Measure Distances Using the Parallax Method

Quick fact

The nearest star, Proxima Centauri, has a parallax angle of only 0.768 arcseconds—equivalent to the width of a human hair seen from 100 meters away. That tiny shift corresponds to a distance of about 4.24 light-years.

Why this is interesting

Hold your thumb out at arm's length and close one eye, then switch eyes—your thumb appears to jump against the background. This everyday effect is exactly how astronomers measure the distances to stars.