THE SOLAR SYSTEM
PLANETARY DATA – SATURNSidereal period 10,759.20 days
Rotation period (equatorial) 10h 13m 59s
Mean orbital velocity 9.6 km/s (6.0 miles/s)
Orbital inclination 2° 29’ 21”.6
Orbital eccentricity 0.056
Apparent diameter max. 20.9”, min. 15.0”
Reciprocal mass, Sun = 1 3498.5
Density, water = 1 0.71
Mass, Earth = 1 95.17
Volume, Earth = 1 744
Escape velocity 32.26 km/s (20.05 miles/s)
Surface gravity, Earth = 1 1.16
Mean surface temperature 180°C
Oblateness 0.1
Albedo 0.61
Maximum magnitude 0.3
Diameter (equatorial) 120,536 km (74,914 miles)
Diameter (polar) 108,728 km (67,575 miles) Saturn,photographed
by Charles Capen with
the 24-inch (61-cm) Lowell
refractor. The ring system
was then wide open. The
Cassini Division in the ring
system is well shown; there
is not a great amount of
detail on the disk – Saturn’s
surface is much less active
than that of Jupiter. Saturn from space:
October 1999, imaged
by the Wide Field and
Planetary Camera 2 from the
Hubble Space Telescope.
The divisions in the ring are
clear – including the Encke
Division near the outer edge
of Ring A.Our view of Saturn today is very different from that of
the astronomer R. A. Proctor in 1882, who wrote:‘Over a region hundreds of thousands of square
miles in extent, the flowing surface of the planet
must be torn by sub-planetary forces. Vast masses
of intensely hot vapour must be poured forth from
beneath, and rising to enormous heights, must
either sweep away the enwrapping mantle of cloud
which had concealed the disturbed surface, or must
itself form into a mass of cloud, recognizable
because of its enormous extent....[Yet] If over
a thousand different regions, each as large as
Yorkshire, the whole surface were to change from
a condition of rest to such activity as corresponds
with the tormented surface of seething metal, and
vast clouds formed over all such regions so as to
hide the actual glow of the surface, our most pow-
erful telescopes would fail to show the slightest
trace of change.’EarthD108- 151 UNIVERSE UK 2003CB 7/4/03 5:12 pm Page 109