Solar System Planets The earth is only one small planet in an extremely large system of planets, satellites, asteroids, meteors and comets that revolve around the sun. This system is referred to as the solar system. A planet is defined as a “celestial body that revolves around a central star and does not shine by its own light ” (Grolier,1992). The only planetary system known to our civilization is our solar system. It is made up of nine planets that differ greatly size and physical characteristics.
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. Following are descriptions of the differences that each of the nine planets have. The first planet to be discussed is Mercury. Mercury is the planet that is closest to the sun at an average distance of about 58 million km, or about 36 million miles. It takes 58.7 days for Mercury to rotate.
The planet rotates one and one half times during each revolution. Mercury has a density and composition close to that of Earth and, like Earth has a magnetic field. This magnetic field is produced from the planets outer core, which is said to be liquid iron. This liquid iron generates a magnetic field with its movement. The atmosphere is extremely thin and contains sodium and potassium. The photographs that have been taken of Mercury’s surface show the planet having craters and steep cliffs.
The temperatures on Mercury reach amazingly high levels of about 430 C, which is about 810 F on the side facing the sun and about -180 C, or about 290 F on the side facing away from the sun. It is speculated that these high temperatures, resulting from the planets proximity to the sun made it impossible for the gases present to become part of the planetary formation or for Mercury to have any type of atmosphere. 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. Venus is known as the sister planet to the Earth. One differences is that Venus is shrouded in thick clouds that completely hide the surface of the planet. 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 a day on Venus equal to 117 earth days. It is thought that this slow rotation may be the reason why Venus has no magnetic field. The atmosphere of Venus made up of 98% carbon dioxide and 2% Nitrogen. This atmosphere also has the presence of helium, neon, and argon.
The surface of Venus is quite a bit like that of the Earth. Cloud particles on Venus are mostly concentrated sulfuric acid. Water and water vapor are very uncommon on Venus. Many scientists hold the opinion that Venus, being close to the sun, was subjected to a kind of extreme greenhouse effect. This effect caused any oceans to evaporate into the atmosphere.
Another viewpoint that is held is that Venus had very little water to begin with. The surface has volcanoes and smooth plains. Much of the volcanic activity on Venus takes the form of Basaltic eruptions that inundate large areas, much as the mare volcanism flooded the impacted basins on the near side of the moon. Because of the distances of the orbits of Venus and Earth from the sun, Venus can never be seen for than three hours before sunrise or three hours after sunset. When Venus is viewed through a telescope, it shows phases like the moon.
Venus rotates very slowly on its axis, in a direction that is opposite to that of Earth. Cloud particles on Venus are mostly concentrated sulfuric acid. Water and water vapor are very uncommon on Venus. Many scientists hold the opinion that Venus, being close to the sun, was subjected to a kind of extreme greenhouse effect.
This effect caused any oceans to evaporate into the atmosphere. Another viewpoint that is held is that Venus had very little water to begin with. Higher-level winds circle the entire planet at 360 km/hr., or 225 mph. However, even with these high velocity winds, near the planets surface more than half of Venus’s tremendously dense atmosphere is practically still.
From the surface up to 10 km, or 6 mi. altitude, wind speeds are only about 3 to 18 km/hr, or about 2 to 11 mph. In the upper atmosphere, the night side of Venus is extremely cold. Day-side temperatures are 40 C, or 104 F but night-side temperatures are -170 C, or 274 F. Scientists theorize that strong winds blow from the day side toward the near vacuum that is caused by the low temperatures on the night-side. Venus has huge active volcanoes, large solidified lava flows, and a vast number of meteorite craters.
The composition of Venus’s dense atmosphere apparently prevents smaller meteorites from crashing into the surface of the planet. A great deal of tectonic activity has taken place on Venus, at least in the past. 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 “. Venus is often referred to by 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. 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 similarity that Mars shares with Earth is the rotation period. Mars rotation period is only thirty-seven minutes longer than Earth’s. This explains the seasonal change similarity that Mars shares with Earth.
It is said that the differences between winter and summer on Mars is more extreme than that on Earth. Mars is extremely hard to analyze and study due blurred effect that is a direct result of the two atmospheres of Mars. Scientists have been able to discover that Mars is fairly small and that changes take place in the surface features upon seasonal changes. The red haze that covers Mars is a result of dust storms.
The thin atmosphere of Mars is composed of carbon dioxide, nitrogen, argon, water vapor and oxygen. Mars is only one of the planets that does not have a 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.
The poles of Mars are iced over and the temperature is about 160 – 170 degrees. Mars shares the volcano characteristic with Venus. The surface is covered 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, and what compels them to gain access to its surface as they once did the moon.
Jupiter …
