page_title: Orbit of the Moon
section_title: Properties
hierarchical_section_title: Orbit of the Moon / Properties
caption_attribution_description: English: Moon's orbit and sizes of Earth and Moon to scale. Earth is at the ellipse's focus left of center. The perigee is on the left, the apogee on the right. The semi-major axis in the horizontal is 0.14% longer than the semi-minor axis in the vertical.
context_page_description: The Moon orbits Earth in the prograde direction and completes one revolution relative to the stars in about 27.32 days and one revolution relative to the Sun in about 29.53 days. Earth and the Moon orbit about their barycentre, which lies about 4,600 km from Earth's center. On average, the distance to the Moon is about 385,000 km from Earth's center, which corresponds to about 60 Earth radii or 1.282 light-seconds.
  With a mean orbital velocity of 1.022 km/s, the Moon covers a distance approximately its diameter, or about half a degree on the celestial sphere, each hour. The Moon differs from most satellites of other planets in that its orbit is close to the ecliptic plane instead of that of its primary equatorial plane. The Moon's orbital plane is inclined by about 5.1° with respect to the ecliptic plane, whereas the Moon's equatorial plane is tilted by only 1.5°.
context_section_description: The properties of the orbit described in this section are approximations. The Moon's orbit around Earth has many irregularities (perturbations), the study of which (lunar theory) has a long history.
caption: Moon's orbit and sizes of Earth and Moon to scale.
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