# Why is it not always light? [duplicate]

Hopefully this is not a silly question, but I was wondering why earth is not always in the light (and any other planet for that matter). I mean, we have billions of stars just in our galaxy that all give off light from all directions. That light has obviously reached is as we can see them shimmering in the night sky.

With that in mind, what has happened to the light from the stars? Has it weakened somehow? (didn't think that was possible) Surely if we are being hit with light from all directions, it makes sense that we should always be illuminated. So what's going on here?

• No, it's not a silly question. You've discovered Olber's paradox. – PM 2Ring Aug 28 '17 at 0:00
• Ahh glad it's not silly! – MCG Aug 28 '17 at 9:30
• There is always light, coming from everywhere, we just cannot see it with our eyes (so small spectrum we indeed see). cmb for more. – J. Chomel Aug 28 '17 at 14:02

• @user6760: On the other hand, frequencies that are "too blue" to be visible are redshifted into the visible range. In fact, this is what makes it easier for us to observe distant galaxies that emit primarily in the UV range (the Lyman $\alpha$ transition from hydrogen). If it were not redshifted, it would be close to impossible to observe from ground because the atmosphere absorbs very effectively in the UV, but for sufficiently distant galaxies, the light becomes visible or even infrared. – pela Aug 28 '17 at 12:29