Physical Data & Dynamical Constants
Selected physical characteristics of planets, planetary satellites, comets and asteroids
are available.
Links to these data are provided in each body's corresponding section below.
In addition, we provide a table representing
astrodynamic constants
(both defining and derived) useful in the field of solar system dynamics.
Radar astrometry for selected solar system bodies is
also provided on a separate page.
Planets
Selected physical parameters
for the planets such as
mass,
mean radius,
density,
absolute magnitude,
geometric albedo,
surface gravity,
and escape velocity
are available in a
table with references.
Planetary Satellites
Selected physical parameters
such as GM, mean radius, mean density, magnitude,
and geometric albedo are available for some
planetary satellites.
These parameters are presented in a
table with references.
In addition, there is a
JPL lunar constants and models technical document
available in PDF format.
Comets and Asteroids
Physical parameters for asteroids
are not well known primarily because
these bodies are so small and there are so many.
The only parameter determined for nearly all asteroids is the absolute magnitude (H)
which can be used to obtain a very rough estimate of an asteroid's size.
However, a few asteroids have other parameters determined including
rotation period,
geometric albedo,
colors (B-V, U-B, I-R),
spectral taxonomic type,
mass (GM),
and bulk density.
Physical parameters for comets
are even less well known than those for asteroids.
Not only are comets difficult to observe because they are small,
but while close enough to observe, they are typically active and thus
their surface is obscured by a coma of gas and dust.
Known physical parameters for any given small body are
available via our small-body database browser.
Alternatively, you can generate custom tables of physical (and other) parameters
for sets of small-bodies using our custom
small-body database search engine.
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