# Microgravity

Microgravity is a condition in which people or objects appear to be weightless. The effects of microgravity can be seen as astronauts and objects float in space. Microgravity can be experienced in other ways as well. “Micro-” means “very small”, so microgravity is a condition in which gravity seems too small. In microgravity, astronauts can hover on their spaceship – or outside, in a spaceship. Heavy objects move around easily. For example, astronauts can move instruments weighing hundreds of pounds with their fingertips. Micro gravity is sometimes called “zero gravity”, but this is misleading.

Is there gravity in space?
Gravity causes each object to pull all other objects into it. Some people think that there is no gravity in space. In fact, a small amount of gravity can be seen everywhere in space. Gravity holds the Moon in its orbit around the Earth. Gravity causes the earth to orbit the sun. In the Milky Way galaxy, it retains the Sun. However, gravity weakens with distance. A spacecraft can travel very far from the earth, and within it a person will feel very little gravity. This is not why things float in a spaceship in orbit. The International Space Station orbits the Earth at an altitude of 200 to 250 miles. At that altitude, the Earth’s gravity is about 90 percent of the planet’s surface. In other words, if a person weighing 100 pounds above the surface of the earth could climb the ladder to the space station, that person would weigh 90 pounds above the ladder.

Why do objects flow in orbit?
If 90 percent of the Earth’s gravity reaches the space station, why do astronauts float there? The answer is because they are free fall. In a vacuum, gravity causes all objects to fall at the same rate. The mass of the object does not matter. When a person drops a hammer and feathers, the air feathers fall more slowly. But without air they would fall at the same acceleration. Some amusement parks have free fall rides, in which a cabin falls with a tall tower. If a person drops an object at the beginning of a fall, that person and object will fall at the same acceleration. As a result, the object appears to be floating in front of the person. That’s what happens on a spaceship. The spacecraft, its crew and any objects in it are orbiting the earth. As they all fall together, the crew and objects appear to be floating compared to the spacecraft.

How does a spaceship fall around the earth?
What does it mean to fall around the earth? Earth’s gravity pulls objects down to the surface. Gravity is also pulling at the space station. As a result, it constantly falls to the surface of the earth. It travels very fast – 17,500 miles per hour. It moves at a speed corresponding to the Earth’s surface curves. If a person throws a baseball, gravity will cause it to bend down. It will fall to the ground very quickly. The spacecraft in an orbit is moving at the correct speed, so its curve of fall corresponds to the curve of the earth. For this reason, the spacecraft falls to the ground, but never hits it. As a result, they fall around the planet. The Moon is in orbit around the Earth for the same reason. The moon also orbits the earth.