Why are celestial motions and forces importani? They explain the world around us. They tell us why and how planets orbit stars, and what hey ens when two objects interact with each other. They also explain the most important force between two objects in space: gravity. Gravity affects us here on Earth: it's why we land when we jump, it keeps our atmosphere from escaping, and it's what makes it so hard for rockets and spacecraft to leave the surface (among many other things). Gravity is also the reason why we would feel lighter on a smaller object like the Moon and why we would feel heavy on a larger planet. These motions and forces boil down to a few key variables: mass, distance, velocity, and acceleration. This assignment is meant to give you a little bit of a mathematical insight into why planets move and how they move. While we use Mercury and Venus as examples, it is beneficial to think what this means for Earth, and consequently for you. In particular, the shape of Earth's orbit, its speed, its distance from the Sun, and its interactions with the Moon, Sun, and other planets. After all, whatever happens to