Why do the Planets Orbit in a Plane?
The night sky is filled with bright dots. Historically, people believed these stars formed a shell around Earth. However, some bright dots, which move against other stars, are planets—derived from Ancient Greek, meaning "Wandering Star." These planets, along with the Sun and Moon, all lie on the ecliptic, a specific path that goes through 12 constellations known as the zodiac. Constellations are arbitrary patterns identified by ancient civilizations, distinct from the science of astronomy...