Here's how it works:

* The Concept: Imagine holding your finger out in front of your face and closing one eye, then the other. Your finger appears to shift slightly relative to the background. This is because of the change in your perspective.

* Stellar Parallax: Astronomers use this same principle to measure the distance to nearby stars. They observe a star from two different points in Earth's orbit around the Sun, six months apart. The star will appear to shift slightly against the background of more distant stars.

* Measuring Distance: The amount of this apparent shift (the parallax angle) is inversely proportional to the star's distance. The smaller the shift, the farther away the star.

Note: Parallax is only effective for relatively close stars, within about 10,000 light-years. For more distant stars, other methods are used to estimate distance.