night sky wallpaper

About night sky wallpaper Android App

this application is a live wallpaper or screensaver of night sky wallpaper set the app as live wallpaper to decorate your phone downloads night sky wallpaper from our store page. we have the best collection of night sky wallpaper. you can also download other live wallpaper in case you don’t find this lwp suitable for you, we had a vast lwp collection.

if there‘s all those stars, why is it dark at night? one hundred billion galaxies, all full of millions of stars, seems like a lot but it isn’t nearly enough to make the night sky as bright as day. if there were an infinite number of stars and the universe was infinitely old, there would be a star everywhere you looked in the night sky and it would be very bright indeed. but the universe isn’t infinitely old. night sky background. it was created approximately 14 billion years ago and since the speed of light is constant, we can only see objects that are less than 14 billion light years away. this means that we are living within a spherical observable universe which is smaller that the total universe and that the light from stars further away from us than 14 billion light years will not have had enough time to reach the earth. in addition, the universe is expanding and all the galaxies, and their stars, are moving away from us. night sky background.

thanks to this, the light from a moving star changes colour in a similar way that sound from a moving ambulance siren changes pitch. the light that we observe from distant receding stars is more red than it would be if they were stationary – the light is red shifted. in many cases the red shift is large enough to move the light out of the visible region of the electromagnetic spectrum. when distances increase, though, so does the time delay. night sky background. for instance, astronauts on the moon experience a 1.5-second time delay in their communications with mission control due to the time it takes the radio signals (which are a form of light) to travel round-trip between earth and the moon. most astronomers agree that the universe is between 10 and 15 billion years old. night sky background. and that means that the maximum distance from which we can receive light is between 10 and 15 billion light-years away. so even if there are more distant galaxies, their light will not yet have had time to reach us.