Here's a video showing 24 hours of air traffic over the globe.
You can either just sit back and marvel at the hypnotic mass of air traffic, moving in patterns like organised colonies of ants, or you can examine some of the characteristics of the activity.
What you see, like all of human life, is ordered by the passage of sunlight across the globe. You are looking at 24 hours of activity. It's clearly northern summer (the Arctic retains its light, the Antarctic doesn't get any).
As you click to start, North America is teeming with activity, and evening is beginning to cast its shadow over the east coast.
Just as darkness begins its push westward over North America, that continent discharges what looks like a salvo of long-range artillery shells toward a Europe that is fast asleep.
Asia and the Pacific, meanwhile, is alive and kicking. Then domestic North America goes to bed.
Just as America's projectiles start to land on Europe, it wakes up and becomes a molten mass of domestic activity but, as if taken by surprise, it takes a while to fire off a return salvo toward North America, which it finally does approaching midday European time.
Meanwhile there is a fairly constant stream of traffic between South America - mostly Brazil and Argentina - and the Iberian Peninsula.
Finally, there are the few lonely flights across the far southern oceans between Australia, South Africa, and South America, plus a one or two flights over the North Pole between North America and Asia.
(Words by Flight's safety and operations editor David Learmount. If you want more from David check out his blog Learmount.... )