If it were night everywhere at the same time, this is what the Earth would look like (click to enlarge). But that strange statement doesn’t explain the importance of this view. What this image shows us is a representation of global wealth. As Vox puts it:
What you see is that in rich countries, light is largely a proxy for population density. Observe the thick cluster of the US Northeastern Megalopolis and the even bigger cluster in northwestern Europe. In poorer regions, however, the map represents not just population density but also the actual availability of electrical lighting. Huge swathes of Africa are barely illuminated at night, and densely populated India looks rather dim.
But of course, if it were night everywhere, that would mean the sun would be gone and we’d all be dead. Money can’t fix that.