You are an astronaut orbiting Earth on the International Space Station (ISS). As you look out of the window, you see Earth below, seemingly suspended in space. Discuss the concept of gravity and how it keeps the ISS in orbit around Earth. Explain the difference between weightlessness and zero gravity. How does the gravitational force between Earth and the ISS result in a stable orbit? Describe the balance of forces that allows the ISS to maintain its orbit without falling back to Earth or drifting into space. How does gravity affect the trajectory of objects in space, and what role does it play in the motion of celestial bodies?