Zero Gravity

In space, astronauts float around as if they weigh nothing. This is called zero gravity or weightlessness. It happens because the astronauts and their spacecraft are falling around Earth together. Everything inside the spacecraft floats, including food, water, and the astronauts themselves.

How Weightlessness Works

The space station is always falling toward Earth. But it is also moving forward so fast that it keeps missing Earth. This is what an orbit is. Because everything inside is falling at the same speed, nothing pushes on anything else. That is why astronauts float. There is still gravity in space, but everyone is falling together.

What Weightlessness Does to the Body

Living without gravity changes the human body. Muscles get weaker because they do not have to work as hard. Bones lose some of their strength too. Fluids move toward the head, making faces look puffy. That is why astronauts exercise for two hours every day on the space station.

Fun Facts

• You can experience about 25 seconds of weightlessness on a special airplane called the Vomit Comet.
• In zero gravity, flames burn in a round ball shape instead of a teardrop shape.
• Tears do not fall in space. They just form a blob on your face.

Did You Know?

The space station is not really in zero gravity. It actually experiences about 90 percent of Earth's gravity. The floating happens because everything is falling together.