The Collaborative International Dictionary of English v.0.48:

Descending \De*scend"ing\, a.
   Of or pertaining to descent; moving downwards.
   [1913 Webster]

   Descending constellations or Descending signs (Astron.),
      those through which the planets descent toward the south.


   Descending node (Astron.), that point in a planet's orbit
      where it intersects the ecliptic in passing southward.

   Descending series (Math.), a series in which each term is
      numerically smaller than the preceding one; also, a series
      arranged according to descending powers of a quantity.
      [1913 Webster]