- ...
*Principia*.^{2.1}
- An excellent discussion of the historical
development of Newtonian mechanics, as well as the physical and
philosophical assumptions which underpin this theory, is
given in Barbour 2001.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.

- ... (acceleration).
^{2.2}
- A
*scalar* is a physical quantity that is invariant under
rotation of the coordinate axes. A *vector* is a physical quantity that transforms in an analogous manner to
a displacement under rotation of the coordinate axes.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.

- ... Sun.
^{5.1}
- Precession can be either prograde (in the same sense as
orbital motion) or
*retrograde* (in the opposite sense). Retrograde precession is often called *regression*.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.

- ... 1995).
^{6.1}
- Actually, the Earth's rotation period relative to the distant stars is called a
*stellar day*,
whereas a sidereal day refers to the Earth's rotation period relative to the vernal equinox (which is a misnomer, because ``sidereal'' means stellar.) A sidereal day is approximately
ms less than a solar day, so the distinction between the two is irrelevant for most purposes.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.

- ... elements.
^{10.1}
- In mathematical terminology, two curves are said to osculate when they touch one another so as to have a common tangent at the point of contact. From the Latin
*osculatus*, ``kissed.''
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.

- ... years.
^{11.1}
- This precession rate is about
times greater than any of the planetary perihelion precession
rates discussed in Sections 5.4 and 10.3.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.

- ... month.
^{11.2}
- A
synodic month, which is
days, is the mean period between successive new moons.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.