![]() This shows the specific configuration at major northern lunistice. Inclination Orbital inclination-the Moon's orbit is inclined by 5.14° to the ecliptic. The Moon's apsidal precession is distinct from the nodal precession of its orbital plane and axial precession of the moon itself. The lunar orbit's major axis – the longest diameter of the orbit, joining its nearest and farthest points, the perigee and apogee, respectively – makes one complete revolution every 8.85 Earth years, or 3,232.6054 days, as it rotates slowly in the same direction as the Moon itself (direct motion) – meaning precesses eastward by 360°. the axes of the ellipse change direction. This orbital precession is called apsidal precession and is the rotation of the Moon's orbit within the orbital plane, i.e. The orientation of the orbit is not fixed in space but rotates over time. Top: polar view bottom: equatorial view Earth's lunar orbit perturbations The mean angular movement relative to an imaginary observer at the Earth–Moon barycentre is 13.176° per day to the east ( J2000.0 epoch). The variance in the Moon's orbital distance corresponds with changes in its tangential and angular speeds, as stated in Kepler's second law. The largest possible apparent diameter of the Moon is the same 12% larger (as perigee versus apogee distances) than the smallest the apparent area is 25% more and so is the amount of light it reflects toward Earth. An event referred to as a " supermoon" occurs when the full Moon is at its closest to Earth (perigee). Since nearer objects appear larger, the Moon's apparent size changes as it moves toward and away from an observer on Earth. The equation of the ellipse yields an eccentricity of 0.0549 and perigee and apogee distances of 362,600 km (225,300 mi) and 405,400 km (251,900 mi) respectively (a difference of 12%). The orbit of the Moon is a nearly circular ellipse about the Earth (the semimajor and semiminor axes are 384,400 km and 383,800 km, respectively: a difference of only 0.16%). Ĭomparison of the Moon's apparent size at lunar perigee– apogee. The Moon's orbit around Earth has many variations ( perturbations) due to the gravitational attraction of the Sun and planets, the study of which ( lunar theory) has a long history. The properties of the orbit described in this section are approximations. ![]() ![]() 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°. The Moon differs from most satellites of other planets in that its orbit is close to the ecliptic plane instead of to its primary's (in this case, Earth's) equatorial plane. ![]() With a mean orbital velocity around the barycentre between the Earth and the Moon, of 1.022 km/s (0.635 miles/s, 2,286 miles/h), the Moon covers a distance approximately its diameter, or about half a degree on the celestial sphere, each hour. On average, the distance to the Moon is about 385,000 km (239,000 mi) from Earth's centre, which corresponds to about 60 Earth radii or 1.282 light-seconds. Earth and the Moon orbit about their barycentre (common centre of mass), which lies about 4,670 km (2,900 mi) from Earth's centre (about 73% of its radius), forming a satellite system called the Earth–Moon system. The Moon orbits Earth in the prograde direction and completes one revolution relative to the Vernal Equinox and the stars in about 27.32 days (a tropical month and sidereal month) and one revolution relative to the Sun in about 29.53 days (a synodic month). While angles and relative sizes are to scale, distances are not. Diagram of the Moon's orbit with respect to the Earth.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |