The empirical rule relating the approximate distances of the
→ solar system
→ planets from the → Sun.
The original formulation was:
a = (n + 4) / 10,
where a is the mean distance of a planet
from the Sun in → astronomical units
and n = 0, 3, 6, 12, 24, 48, 96, 192 (doubling for each successive planet).
The planets were seen to
fit this sequence quite well, provided the → asteroids
between → Mars and → Jupiter
are counted as one planet, as did → Uranus
discovered in 1781. However,
→ Neptune and the ex-planet
→ Pluto do not conform to the rule.
The question of
whether there is any physical significance to the “law,” i.e. some dynamical reason that
will explain
planetary orbit spacing has led to much discussion during the past two
centuries. Today, many astronomers are
very skeptical and consider this “laws” to be numerical coincidence.
See also: Named after the German mathematician Johann Titius (1729-1796), who
first found the law in 1766, and the German astronomer Johann Elert Bode (1747-1826),
who published it in 1772; → law.
