Apsides
APSIDES and APSE, in mechanics, either of the two points of an orbit which are nearest to and farthest from the centre of motion. They are called the lower or nearer, and the higher or more distant apsides respectively. The "line of apsides" is that which joins them, forming the major axis of the orbit.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)
