lunar orbit

lunar orbit (plural lunar orbits)

1. The orbit of the Moon around the Earth. [from 17th c.]
   • 1690, John Partridge, Merlinus liberatus‎, page 43:

     From the present position of the lunar orbit, it does not appear that any very striking occultations will happen in this country during the present year; [...]

   • 1755, Philosophical Transactions of the Royal Society of London‎, page 389:

     But whereas the plane of the lunar orbit, which is always inclined to the plane of the ecliptic in an angle of about 5 degrees, never continues in a constant position [...]

   • 1855, Samuel Elliott Coues, Arithmetical Calculations of the Elements of the Orbit of the Moon:

     With these preliminary explanations, the reader will be prepared for the discussion of the relation of the eccentricity of the lunar orbit to its inclination to the plane of the ecliptic.

   • 1865, Alexander Hamilton Howe, A Theoretical inquiry into the physical cause of epidemic diseases:

     The lunar orbit and the solar orbit do not coincide, but intersect each other at an angle of 5°8'48". The place where the lunar orbit intersects the solar orbit is called the "Lunar Node."

   • 1967, D. L. Mootchnik, J. Kork, Lunar Orbit Mission Analysis:

     If the lunar orbit is assumed circular, then the rotation rate and the earth-moon distance are constant [...]

2. The orbit of an object around the Moon. [from 20th c.]

   Synonym: selenocentric orbit

• US space programs such as the Apollo program have restricted usage of this term to sense 2 although the word selenocentric orbit is more precise for that sense.