An astronaut is a trained professional who travels into space to conduct research and perform tasks outside of Earth’s atmosphere. They undergo rigorous training to prepare for the physical and mental challenges of space travel, including learning how to operate spacecraft and conduct scientific experiments. Astronauts often work for space agencies like NASA or ESA and may spend months aboard the International Space Station (ISS). Their missions can involve studying the effects of microgravity on the human body, testing new technologies, and conducting experiments that benefit life on Earth.