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In contrast, the Lunar distance (LD or ), or Earth–Moon characteristic distance, is a unit of measure in astronomy. More technically, it is the semi-major axis of the geocentric lunar orbit . The lunar distance is on average approximately 385,000 km (239,000 mi), or 1.28 light-seconds ; this is roughly 30 times Earth's diameter or 9.5 times ...
Finding Greenwich time while at sea using a lunar distance. The lunar distance is the angle between the Moon and a star (or the Sun). In the above illustration the star Regulus is used. The altitudes of the two bodies are used to make corrections and determine the time. In celestial navigation, lunar distance, also called a lunar, is the ...
The semi-major axis of the geocentric lunar orbit, called the lunar distance, is approximately 400,000 km (250,000 miles or 1.28 light-seconds), comparable to going around Earth 9.5 times. [178] The Moon makes a complete orbit around Earth with respect to the fixed stars, its sidereal period, about once every 27.3 days.
Lunar distance: 0.0026 — Average distance from Earth (which the Apollo missions took about 3 days to travel) — Solar radius: 0.005 — Radius of the Sun (695 500 km, 432 450 mi, a hundred times the radius of Earth or ten times the average radius of Jupiter) — Light-minute: 0.12 — Distance light travels in one minute — Mercury: 0.39 —
Proposition 17a in al-Tusi's medieval Arabic version of the book On Sizes states that the ratio of the distance of the vertex of the shadow cone from the center of the Moon (when the Moon is on the axis [that is, at the middle of an eclipse] of the cone containing the Earth and the Sun) to the distance of the center of the Moon from the center ...
The observed angle must be corrected for the effects of refraction and parallax, like any celestial sight. To make this correction, the navigator measures the altitudes of the Moon and Sun (or another star) at about the same time as the lunar distance angle. Only rough values for the altitudes are required.
[19] [20] Planned orbit for the NASA Lunar Gateway in circa 2024, as a highly-elliptical seven-day near-rectilinear halo orbit around the Moon, which would bring the small space station within 3,000 kilometers (1,900 mi) of the lunar north pole at closest approach and as far away as 70,000 kilometers (43,000 mi) over the lunar south pole. [21 ...
Modern Lunar Laser Ranging data can be fit with a 1 cm weighted rms residual. The center of Earth to center of Moon distance is computed by a program that numerically integrates the lunar and planetary orbits accounting for the gravitational attraction of the Sun, planets, and a selection of asteroids. [36] [23]