What Happens to the Human Body in Zero Gravity?

By: Ahana Suresh-

Life on Earth is shaped by gravity, so when humans enter space and experience zero gravity, the body begins to change in surprising ways. In a weightless environment, astronauts float instead of walk, and their bodies no longer need to work against gravity. While this may sound fun, it comes with serious effects.

One of the first changes occurs in the muscles and bones. Without gravity pulling the body downward, muscles are used far less, causing them to weaken and shrink over time. Bones also lose density because they no longer support body weight, making them more fragile. Astronauts must exercise for hours each day to slow this process.

Zero gravity also affects the circulatory system. On Earth, gravity helps pull blood toward the lower body. In space, fluids shirt upward toward the head, causing puffy faces and pressure in the skill. This fluid shift can also effect vision, leading to blurred eye sign for some astronauts.

Even the immune system can weaken in space, making astronauts more vulnerable to illness. Despite these challenges, studying the human body in zero gravity helps scientists prepare for long missions, such as traveling to Mars, and deepen our understanding of how the body adapts to extreme environments.