Imagine standing miles away from a giant metal tower on a clear morning. You hear a voice over a loudspeaker counting down: "Ten, nine, eight..." Your heart races as the numbers get smaller. Suddenly, at zero, a massive cloud of white smoke pours out from the bottom of the rocket. A bright orange flame appears, and the ground begins to rumble. This is the start of a rocket launch, one of the most exciting events in science.
A rocket is not like an airplane. While airplanes use wings to lift themselves into the air, a rocket uses something called thrust. Thrust is a powerful force that pushes an object forward. Inside the rocket’s engines, liquid or solid fuel is burned to create hot gases. These gases shoot out of the bottom of the rocket at very high speeds. Because the gas is pushing down so hard, the rocket is pushed upward. This follows a famous rule of science: for every action, there is an equal and opposite reaction.
Most rockets are built in parts called stages. As the rocket climbs higher, it uses up its fuel. Once a fuel tank is empty, that part of the rocket falls away to make the craft lighter. This helps the rocket move faster and faster. To get all the way into space, a rocket must travel at an incredible speed of about 17,500 miles per hour. This is fast enough to break away from the pull of Earth’s gravity, which is the invisible force that tries to pull everything back down to the ground.
Once the rocket reaches the edge of space, it releases its payload. A payload is the important cargo the rocket is carrying, such as a satellite, supplies for an space station, or even astronauts. While the launch only lasts a few minutes, it takes years of planning and thousands of people to make sure everything goes perfectly. Every successful launch is a giant leap for human discovery.
