Planets And Solar System
Planets and Solar System The Planets and the Solar System Planets 2 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 of wrinkles that might form in the
crust if the interior of the planet shrank slightly (Morrison, 74, 1993). It is
speculated that it was the solidification of Mercury's metallic core that caused
this global shrinkage. Mercury is also . . . enriched in metal or depleted of
rock (Morrison, 74, 1993). It is also believed that some of the inner core of
Mercury is still in a fluid state. Scientists also believe that Mercury's
surface is made partially of silicate rock. The best way to describe Mercury is,
. . . small, heavily cratered and airless (Morrison, 71, 1993).
Venus is the
second closest planet to the sun and is said to . . . most closely resemble
Earth in size, density, and distance from the sun (Thompson/Turk, 542, 1993).
Venus is known to most scientists as the sister planet to the Earth. It is
called this because it closely resembles the Earth's mass, density and diameter.
The only thing different is that Venus is shrouded in thick clouds that
completely hide the surface of the planet (Grolier, 1992). The surface
temperature is also much warmer than that of Earth. Venus completes one
revolution around the sun in 224.7 days. This makes the Venusian day equal to
117 earth days. It is thought that this slow rotation may be the reason why
Venus has no magnetic field. Planets 4 The atmosphere of Venus made up of 98%
carbon dioxide and 2% Nitrogen. This atmosphere also has the presence of helium,
neon and argon. This is yet another thing which makes Venus different from
Earth. The surface of Venus is quite a bit like that of the Earth. The surface
has volcanoes and smooth plains. Much of the volcanic activity on Venus takes
the form of Basaltic eruptions that inundate large ares, much as the mare
volcanism flooded the impacted basins on the near side of the moon (Morrison,
93, 1993). One thing that differs from Earth is that there is no water liquid on
the Venusian surface. Some of the scientific data that follows was taken out of
Cattermole's book. The mean distance from the sun is 108.20 Km. The equatorial
diameter is 12,012 Km and the equatorial rotation is 243 days. Finally the mass
of Venus is 4.87*10^24 (Cattermole, 63, 1993). Venus, although different than
Earth, is still our sister planet. Mars is the fourth furthest away from the sun
and is recognized by its reddish color. Mars is also very much like the Earth.
More than any other planet in the solar system, Mars has characteristics that
make it an Earth-like world (Grolier, 1992). One thing that is very similar to
Earth is the rotation period. Mars rotation period is only thirty seven minutes
longer than the Earth's. This would explain why Mars has significant seasonal
changes just as Earth does. It is believed that the Planets 5 difference between
winter and summer on Mars is even greater than on Earth. Mars is extremely hard
to understand due to the effect of blurring that is caused by the two
atmospheres of Mars.
