A hot-air balloon has no engine and no wings, but it can fly high above the ground. How does it work? The answer is simple: hot air is lighter than cold air, so it goes up.
A balloon has three main parts: a huge bag called the envelope, a burner, and a basket for the passengers. The burner heats the air inside the envelope. When the air inside is hotter than the air outside, the balloon rises.
The first people to fly in a hot-air balloon flew over Paris in 1783. The balloon was made by two French brothers, Joseph and Etienne Montgolfier. The flight lasted about twenty-five minutes.
Today, pilots can make a balloon go up or down, but they cannot steer it left or right. To change direction, they look for winds that blow in different directions at different heights. That is why every balloon flight is a small adventure.