قانون ِ کاسینی qânun-e Cassini
*Fr.: loi de Cassini*
Any of the three empirical laws governing the rotational dynamics of the
→ *Moon*:
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*. |