Bright Night
![](https://supernova.eso.org/static/archives/exhibitionimages/screen/Earthlights_dmsp-13x.jpg)
Credit: NASA/Goddard Space Flight Center Scientific Visualization Studi
Electric lights illuminate the night all around the globe. That makes it hard for astronomers to find a good spot for their observatories. It also affects the circadian rhythm of humans and animals alike.