How Does Stellar parallax and measuring distance Work?

Stellar parallax is like watching a toy car move closer and farther away from you while sitting on a swing.

Imagine you're sitting on a swing in your backyard. You look at a toy car that's far away, it seems still. But when you swing forward, the car looks like it’s moving backward. When you swing back, it looks like it’s moving forward again. This trick happens because your viewpoint changes as you swing, this is parallax.

Stars work the same way, but on a much bigger scale. Imagine a star that's far away from Earth. We look at it from two different points in Earth’s orbit, once when Earth is on one side of the Sun, and again six months later when Earth is on the other side.

Because our viewpoint changes, the star seems to move slightly against the background of more distant stars, this tiny shift is called stellar parallax. Scientists measure how much the star moves, and from that, they can figure out how far away it is.

The farther a star is, the smaller its parallax shift, just like how the toy car looks less wobbly when it's closer to you. This lets scientists calculate distances in space, using nothing but careful measurements and a bit of clever thinking!