 Hello everyone and welcome to our universe. Today we'll be answering the question, what is redshift? So this is going to be quite a quick video, basically explaining what redshift really is. So astronomers often use the term redshift to describe how far away objects really are. To understand what cosmic redshift is, we must think about sound. A great example of this is a police car. You hear it's siren because the waves travel through the air into your ear. If the police car is moving then the sounds in front of it are compressed and create a higher frequency sound. And the sound waves behind it are stretched out, creating a lower frequency sound. As the police car passes in front of you, you would hear the familiar Doppler shift. Light is quite similar. It also travels in waves and it's quite a similar process to what is happening within the waves. Light waves are able to be compressed and stretched, just like sound. But with sound you would change the frequency. But with light you change the colour. Blue light has shorter wavelengths than red. When an object in the space moves towards us, the light waves are compressed into higher frequencies. And this is why the light is blue shifted. It's shifted towards the shorter wavelengths. But when an object moves away from us, the light waves are now stretched. These waves now go into the lower frequencies. And this is what's known when light goes to redshifted. It shifts to the longer wavelengths. So how do we calculate distance by using redshift? Well the light from the most distant objects in our universe is redshifted. Very redshifted. As seen from Earth. And this is basically because the universe is expanding. That the further away a galaxy is, the faster it is moving. And the faster a galaxy moves, the more its light is redshifted. So by measuring the amount of redshift is a great way to measure the distance of the galaxy relative to Earth. By using cosmic redshift, astronomers are able to measure the distance of galaxies as far as 12 billion light years away. With the latest technology that we have in space telescopes and ground based telescopes, we are pushing this cosmic redshift limit even further back. Looking into the deep parts of the universe and telling us really how the universe was created and how it evolved. So I hope that's given you a great insight into what is redshift. If you'd like to know any more about redshift or the expanding universe itself, I'll put some links in the description below. And as always, if you've enjoyed the video, click the like button and if you want to support the channel, click subscribe and support our Patreon page. Thank you for watching and thank you for your support.