Astronomy Practice Exam 2026 – Complete Preparation Guide

Astronauts feel weightless in space primarily because they are in a constant state of free fall. While it might seem that gravity is absent in space, this is a common misconception. In fact, gravitational forces are still very much present; for example, the International Space Station (ISS) orbits Earth at a height where gravity is about 90% as strong as it is on the planet's surface.

When a spacecraft orbits Earth, both the spacecraft and the astronauts inside are accelerating towards Earth due to gravity. However, the spacecraft is also moving forward at a high enough velocity that it keeps missing the Earth, creating a continuous free fall around the planet. This state causes the astronauts to experience what is often referred to as microgravity, leading to the sensation of weightlessness. Despite the presence of gravitational pull, because everything is falling together, astronauts do not feel the force of gravity acting on them as they would on Earth.

Understanding the phenomenon of free fall is crucial, as it explains why astronauts float inside the spacecraft and illustrates the relationship between motion and gravitational forces in a microgravity environment.