Definition of apsis in English:

apsis

Line breaks: apsis
Pronunciation: /ˈapsɪs
 
/

noun (plural apsides /-diːz/)

  • Either of two points on the orbit of a planet or satellite that are nearest to or furthest from the body round which it moves.
    More example sentences
    • In particular there was, according to Aryabhata I, a basic period of 4320000 years called a mahayuga and it was assumed that the sun, the moon, their apsis and node, and the planets reached perfect conjunctions after this period.
    • He noted that if the bob was drawn back and released then it followed an elliptical path, and moreover the major axis rotated in the direction of revolution exactly as did the apsides of the moon's orbit.
    • For the moon, the line of apsides completes one revolution around the sky in a period of 8.85 years.

Derivatives

apsidal

adjective
More example sentences
  • The trajectory is a half ellipse with its apsidal axis coinciding with Q1Q2, and the trajectory conic is the well-known Hohmann's ellipse.
  • Both the apsidal axis and the moon’s nodal axis rotate.
  • By latus component we mean the component of the orbital velocity in the direction perpendicular to the apsidal axis of the orbit.

Origin

early 17th century (denoting the orbit of a planet): via Latin from Greek apsis, hapsis 'arch, vault', perhaps from haptein 'fasten, join'.

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