why does the earth tilt
Earth 's orbital plane is known as the ecliptic plane, and Earth's tilt is known to astronomers as the obliquity of the ecliptic, being the angle between the ecliptic and the celestial equator on the celestial sphere. It is denoted by the Greek letter Îµ.t an obliquity of zero, these lines point in the same direction i.e. the rotational axis is perpendicular to the orbital plane. Axial tilt differs from inclination. Because the planet Venus has an axial tilt of 177Â° its rotation can be considered retrograde, opposite that of most of the other planets.