Flexi Says: The ecliptic plane is defined as the imaginary plane containing the Earth's orbit around the sun. As viewed from Earth, the Sun's path through the sky over the course of the year travels through the ecliptic plane. The paths of the planets in our solar system all tend to lie near this plane, since they were all formed from the same flattened disc of material that orbited the Sun early in the formation of the solar system. The constellations that surround the ecliptic are collectively called the zodiac. The Sun and planets appear to move through these constellations as viewed from Earth over the course of the year.