What is redshift?

Redshift is when light from something far away seems to change color because it’s moving away from us.

Imagine you’re on a swing, and your friend is throwing you a ball while riding their bike away from you. The ball comes at you slower than it would if they were staying still, that’s like redshift!

Light acts like a wave, and when something is moving away from us, those waves stretch out, making the light look more red, we call this redshift. If the thing is moving toward us, the waves get squeezed together, and the light looks more blue, that’s called blueshift.

Scientists use redshift to figure out how fast stars and galaxies are moving away from Earth. It helps them understand that the universe is expanding, just like when you blow up a balloon, everything on it moves apart!