A sheep, a duck and a rooster went first
The first passengers to fly in a BALLOON were farm animals. In September 1783 the Montgolfier brothers sent a sheep, a duck and a rooster up in front of the French king at Versailles, because nobody knew whether the air high above the ground was safe to breathe. The duck was the control: it could already fly that high, so if it came down unharmed and the sheep did not, the height was the problem.
All three landed safely after about eight minutes. Two months later two men went up over Paris, and human flight had begun — 120 years before anyone managed it with an engine.
Why hot air lifts
Heat the air inside the ENVELOPE and it expands, so some of it spills out of the open mouth at the bottom. There is now less air inside than there was, the whole BALLOON weighs less than the cool air it displaces, and up it goes — exactly the way a bubble rises through water.
It takes a surprising amount of air to lift a little weight. A balloon carrying a PILOT and a few passengers holds something like 2,800 cubic metres, enough to fill a good-sized house, and the PROPANE BURNER above the BASKET puts out heat on the scale of a hundred domestic boilers when it fires. Let the air cool and the balloon sinks; fire the burner again and it will RISE.
Steering means choosing a height
A balloon has no engine, no rudder and no way to go sideways. It travels with the WIND, at exactly the speed of the wind, so the basket feels perfectly still in the air even at thirty miles an hour.
The steering trick is that wind blows in slightly different directions at different heights. A good PILOT studies the forecast for each layer, then climbs or descends to find a breeze heading the right way and lets the balloon DRIFT along on it. It is less like driving and more like choosing which escalator to step onto. Because nobody can be sure exactly where it will finish, a chase crew follows by road, and a polite conversation with a farmer is a normal part of any LANDING.
The other kind of balloon
Not every balloon uses heat. Fill the ENVELOPE with hydrogen or helium and it floats without any BURNER at all, which is how the highest flights are made. Twice a day, at hundreds of sites around the world, meteorologists release weather balloons carrying small instrument packages that radio back temperature, pressure and humidity as they climb. The balloon swells as the air around it thins until, somewhere around 30 kilometres up, it bursts and the instruments parachute down.
Those readings are the raw material of every weather forecast you have ever seen, gathered by something that costs less than a bicycle and is never seen again.
Records and mass gatherings
Balloonists kept chasing the obvious prize for decades, and in 1999 Bertrand Piccard and Brian Jones finally flew one non-stop around the world, taking just under twenty days and landing in the Egyptian desert with almost no fuel left.
Most ballooning is gentler than that. The biggest gathering of all, the FESTIVAL at Albuquerque in New Mexico, fills the sky each autumn with hundreds of balloons launching in waves, the COLORFUL ones shaped like animals and cartoon characters among them. They go up at dawn for a practical reason: the WIND is calmest in the first hours after sunrise, before the ground warms and stirs the air.