What is "descending constellations"

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

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.