Scientists do know, however, that Mars is relatively small
and that changes take place in the surface features when the seasons change. It
is also known that dust storms are prevalent and leaves the surface of Mars
covered by a red haze. Mars has a very thin atmosphere which is composed of
carbon dioxide, nitrogen, argon, water vapor and oxygen. Mars also has no
magnetic field. Because the atmosphere of mars is so thin, wind velocities up to
several hundred Km per hour are required to raise the dust particles during a
dust storm, and these fast- moving particles erode structures with a
sand-blasting effect (Grolier, 1992). Therefore, the surface is basically
plain-like and covered with large craters. There are also some areas where the
rock is jumbled. The poles of Mars are iced over and the temperature is about
160 - 170 degrees K. Mars also has its share of volcanoes. Most of these
volcanoes are shield volcanoes. The surface is littered with winding channels
that resemble river channels that have dried up over time. Scientists believe
that water once existed and caused the formation of these channels. It is said
that, Mars remains the best candidate for life in the solar system outside of
the Earth, and that is what makes Mars so interesting to scientists. Jupiter is
the fifth planet and is the most massive of all Planets 6 the planets in this
solar system. Its mass represents more than two-thirds of the total mass of all
the planets, or 318 times the mass of the Earth. Jupiters density is quite low
at 1.3 g/cubic cm. The atmosphere of Jupiter contains water, ammonia, methane
and carbon. It is thought by scientists that there are three cloud layers. The
wind activity on Jupiter is quite fierce and moves in jet streams parallel to
the equator. The weather on Jupiter is still very hard for scientists to
understand. There is not enough information to truly understand how the weather
is on this planet. Jupiter is most known by the normal citizen by the rings it
has.
These rings are very diffuse. The ring particles must generally be about as
big as the wavelength of light, that is, only a few microns (Grolier, 1992).
That is why these rings are faint or diffuse. The rings are what Jupiter is
known for. Saturn is a planet which is also known for its rings and when viewed
has a yellow or grayish color. The color is from the gaseous atmosphere and the
dust particles in that atmosphere. The atmosphere is mostly a clear
hydrogen-helium atmosphere. There are also traces of methane, phosphine, ethane,
and acetylene. This atmosphere is much different than that of the Earth's.
Saturn orbits the sun with a period of 29.4577 tropical years. It is 1.427
billion Km away from the sun and is therefore a cold planet. It has an
equatorial diameter of 120,660 Km which Planets 7 makes it the second largest
planet in our solar system. The next planet is Uranus. The main problem
scientists have with Uranus is that, the lack of visible surface features means
that it is difficult to measure the rotation period of Uranus (Hunt/Moore, 388,
1983). Uranus has an equatorial diameter of 51,000 Km which is almost four times
as much as Earth. The atmosphere is mostly methane gas and therefore the planet
has a red tint or a blueish green color. Uranus also has rings but unlike Saturn
these rings have almost no small particles. Scientists are not as concerned with
this planet. Neptune is the last of the gaseous planets in our solar system. Its
atmosphere is much like Uranus's because it is mostly helium and hydrogen. It
also contains methane. Neptune has a diameter of 49,500 Km and a mass 17.22
times that of the Earth. It has an average density of 1.67 /cm^3 (Grolier,
1992). Neptune also has rings like its other gaseous partners, but they are very
faint. Not a great deal is known about Neptune. It is widely studied by
scientists and that makes it an important planet. The final planet, which is
also the smallest, and the furthest away from the sun is Pluto. This planet is
very hard to see therefore not a lot is known about its physical
characteristics. Scientists do know that it has a thin methane atmosphere.
Little is known about this planet because it is so far away from the Earth and
the sun. Scientists are always learning new things and more data will arise in
the future. Planets 8
