قانون ِ کاسینی
Fr.: loi de Cassini
Any of the three empirical laws governing the rotational dynamics of the
1) The Moon rotates uniformly about its polar axis with a
→ rotational period
equal to the mean → sidereal period
of its orbit about the Earth.
2) The → inclination of the Moon's equator to the
→ ecliptic is a
constant angle approximately 1.5°.
3) The → ascending node of the lunar orbit on the ecliptic
coincides with the → descending node
of the lunar equator on the ecliptic. This
law could also be expressed as: the spin axis and the normals to
the ecliptic and orbit plane remain coplanar
(Noyelles, 2009, Icarus, 202, 225).
Named after Jean-Dominique Cassini (1625-1712), French astronomer of Italian origin,
who established these laws in 1693 (Traité de l'origine et du progrès de l'astronomie),
; → law.