Appendix A - Solar System Data

Summary

And he that calls on thee, let him bring forth

Eternal numbers to outlive long date.

William Shakespeare, Sonnet XXXVIII

Introduction

This appendix contains lists of important astronomical constants, information about the use of the Julian date, orbital data, and physical properties of the known planets and satellites, as well as limited information about some of the minor bodies that make up the solar system.

The data are taken from a number of sources including The Astronomical Almanac for the Year 1995 (HMSO, 1994), The Explanatory Supplement to the Astronomical Almanac (Seidelmann, 1992), and the article by Yoder (1995) and the references therein. The data from the first of these publications is reproduced with permission from HMSO. Other sources of data are indicated in the appropriate sections.

Astronomical Constants

In 1976 the International Astronomical Union (IAU) defined a system of astronomical constants. The IAU system has units of length (the astronomical unit), mass (the mass of the Sun), and time (the day). If the units of length, mass, and time are the astronomical units of these quantities then the astronomical unit of length is the length for which the Gaussian gravitational constant k has the value 0.01720209895. In effect, if the gravitational constant G is expressed in the astronomical units of length, mass, and time then k² = G. Some of the 1976 IAU constants are given in Table A1.1.