Astronomy
Astrometry: Precise Measurement of Star Positions and Motions
Quick fact
The Gaia space telescope measures the positions of nearly two billion stars to an accuracy of 0.00001 arcseconds—equivalent to measuring the width of a human hair from 1,000 kilometers away.
Why this is interesting
When you look at the night sky, the stars appear fixed and unchanging—but they are actually moving across vast distances. How do astronomers measure these tiny, slow motions with incredible precision?