Cosmic infrared background

A long time ago, when the Universe was just beginning, there were many, many stars being born. These stars gave off light, just like the sun gives off light that allows us to see during the day. But some of this light wasn't visible to our eyes - it was in a form called infrared light.

Infrared light is kind of like heat - it's a type of light that we can't see, but it can tell us a lot about what's happening in the Universe. As these stars were born and grew older, they released more and more infrared light into the Universe.

However, not all of this light made it to us here on Earth. Some of it got absorbed or blocked by other objects in space. But scientists have ways of detecting this leftover infrared light, and that's what we call the cosmic infrared background.

It's like a very faint glow that's present all around us, even when it's very dark. And by studying this glow, scientists can learn more about how the Universe has changed and evolved over time.