Eccentricity (orbital)

Orbital eccentricity measures how much an orbit deviates from being a perfect circle. It is a number between 0 and 1: 0 indicates a perfectly circular orbit, while values closer to 1 show a more elongated, oval shape. For example, Earth's orbit has a low eccentricity, making it almost circular, whereas Mercury's orbit is more elongated. Eccentricity helps scientists understand the shape of celestial orbits and how objects move around each other in space. A higher eccentricity means a more elongated orbit, affecting the distance between the orbiting object and its focus point over time.