The skies look a lot more crowded today than they did a century ago. At any given moment, there are 9700 airplanes traveling through the air on average. Saturday, June 30 was an especially busy day for air travelers: Flightradar24 recorded 202,157 flights, the most the flight-tracking app has ever documented in a single day.
Since 2006, people have used Flightradar24 to see visualizations of aircraft making trips around the world. Each tiny yellow plane depicted on their map uses data from airlines and airports, and users can click the icons to learn the route, model, speed, altitude, and departure and arrival time of each craft.
Another way to use the app is to take in all the visual information at once. The sped-up GIF below from Flightradar24 gives you an idea of just how densely-packed the skies were that day, with thousands of planes swarming to and from the planet's most populous areas.
Commercial flight data is more accessible to the public than many people realize. To build their real-time maps, Flightradar24 uses radar, ADS-B (the technology planes use to broadcast their location), and MLAT (a method used to calculate the position of planes by measuring the time it takes them to receive a signal). To get an even more detailed scoop on the status of an airplane, you can tune into the live feed of a specific airport's air traffic control channel.