Planets and Solar System

"A planet is a celestial body that revolves around a


central star and does not shine by its own light " (Grolier,


1992).   The only planetary system that is known to man is our


solar system.   It is made up of nine planets which range in size


and make-up.   The nine major planets in our solar system are


Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and


Pluto.   There are also many other minor planets which are also in


our solar system, but they are unimportant compared to the nine


major planets.   In this paper I will discuss the planets and how


they are each unique.


    Mercury which is the planet that is closest to the sun is


the first planet I will discuss.   Mercury is the smallest of the


inner planets.   It is speculated that the heat from the sun made


it impossible for the gases present to become part of the


planetary formation.   The surface of Mercury is extremely hot.


It is approximately 470 degrees celsius on the surface and is


thought to be even hotter at the two " hot spots."   These " hot


spots " are on opposite ends of the equator.   It is the heat of


the surface that makes it impossible for Mercury to have any type


of atmosphere.


    Mercury orbits the sun once every 88 days and has a true


rotation period of 58.6 days.   " It is the closest planet to the


sun and therefore orbits faster than any other planet "


(Thompson/Turk, 542, 1993).   It is said that Mercury rotates


three times for every two trips around the sun, so that during





                                                              Planets   3


every alternate perihelon passage the same face points directly


at the sun.   " Geologically, the most remarkable features of


Mercury are compressional cliffs or faults, just the sort...