Returning to Earth is easy; you just fall. The hard part is returning alive. For the time being, astronauts travel to and from space in capsules that land using parachutes, either on land or at sea. While the descent ends with a somewhat gentle float down to earth, it begins with fire. As the capsule enters Earth’s atmosphere, its exterior heats up, making it glow white-hot as the atmosphere around it lights up in ways that can be seen from far below.