How Does Red shift | Astrophysics | Physics | FuseSchool Work?

Red shift is when light from something far away looks more reddish because it’s moving away from us, like when a siren on a fire truck sounds lower as it drives past you.

Imagine you're playing with a toy car that has a bell on top. When the car moves toward you, the sound of the bell gets higher and louder. But when it zooms away, the sound gets deeper and quieter. That’s Doppler effect, the same thing happens with light.

When stars or galaxies move away from us in space, the light they send out stretches out as it travels through the universe. This stretching makes the light look more red, even if the star was originally white or blue. Scientists call this red shift.

Think of it like a rubber band. If you stretch it, the marks on it get farther apart. Light works the same way: when something is moving away, its light waves get stretched out, and red is the color that shows up most clearly from that stretching.

So, by looking at how much the light has shifted to red, scientists can tell how fast something in space is moving away from us, just like you can tell a toy car is going away by hearing the bell sound get deeper.