Axis Tilt Definition May 2026

, formally known as obliquity , is the angle between an object's rotational axis and a line perpendicular to its orbital plane. More commonly, it is described as the angle between the rotational axis and the orbital plane itself (the complement of the former). For a planet, this tilt determines the seasonal variation on that body.

For Earth, the current mean obliquity is approximately (or 23°26′). This value is not constant; it varies between 22.1° and 24.5° over a cycle of approximately 41,000 years due to gravitational perturbations from other planets (a Milankovitch cycle). axis tilt definition

1. Formal Definition

It is a common pedagogical error to define axis tilt as "the angle of the Earth's axis from the vertical." While functionally equivalent, the precise astronomical definition references the orbital plane (the ecliptic). Thus, Earth’s axis is tilted 23.44° away from the perpendicular to its orbital path. , formally known as obliquity , is the

| Planet | Axis Tilt (Obliquity) | Notable Effect | | :--- | :--- | :--- | | Mercury | ~0.03° | No seasons | | Earth | | Temperate seasons | | Mars | 25.19° | Similar seasons, but more extreme due to eccentric orbit | | Jupiter | 3.13° | Negligible seasonal variation | | Saturn | 26.73° | Pronounced seasons (7+ years each) | | Uranus | 97.77° | Extreme seasons; poles face Sun directly | For Earth, the current mean obliquity is approximately