In the article “Five things that happen to your body in space” the health science professor Naomi Brooks from the Conversation explains physical changes that happen when humans live in space. The first change is that the body gets weaker. The skeletal system on Earth uses muscles to make body movements using weight from the center-pulling gravity of Earth. But in space, there is no gravity so bodies don’t work the way that they are supposed to. Astronauts working on the International Space Station that orbits earth lost part of their muscle strength even when the exercised every day. Scientists worry that this will be a problem for people who will make the long journey to Mars. The second change is a change in the heart. On Earth, the veins in the legs work against gravity to return blood to the heart; but without gravity, the heart, veins, and arteries change. There is less blood flow and the heart beats slower in space. The longer a person is in space the changes become more serious. The size and shape of the heart are altered because there is no gravity. The third change is less oxygen flow due to less blood flow. This makes it harder to exercise. The fourth change is the amount of bone mass. On Earth, bones of human are created in careful accordance with gravity levels and weights. But since there is no gravity in space there is much less weight put on the bones, throwing off the balance of our bone cells and causing them to create less bone. The fifth and final change is the immune system. The immune system is affected by the stress, low gravity, change in sleep pattern, and lesser amounts of contact with people in space, which affects its ability to do its job. This article is important to scientists who are studying the effects of low-gravity and zero-gravity situations on the human body. This can help them find ways to counteract, slow or stop the changes in the body due to low-gravity and zero-gravity situations. This article is important to astronauts who want to go into space because they can get ready for the changes that will happen to them. This article can teach students how the gravitational pulls of different places can affect the human body. Finally this article is important to N.A.S.A. and other international space agencies because they can use this information to their advantage when trying to colonize planets by being prepared for the changes.