A planet is a celestial body that revolves around a central star and does notshine by its own light ” (Grolier, 1992). The only planetary system that isknown to man is our solar system. It is made up of nine planets which range insize 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 manyother minor planets which are also in our solar system, but they are unimportantcompared to the nine major planets.
In this paper I will discuss the planets andhow they are each unique. Mercury which is the planet that is closest to the sunis the first planet I will discuss. Mercury is the smallest of the innerplanets. It is speculated that the heat from the sun made it impossible for thegases present to become part of the planetary formation. The surface of Mercuryis extremely hot.
It is approximately 470 degrees celsius on the surface and isthought to be even hotter at the two ” hot spots. ” These ” hotspots ” are on opposite ends of the equator. It is the heat of the surfacethat makes it impossible for Mercury to have any type of atmosphere. Mercuryorbits 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 anyother planet ” (Thompson/Turk, 542, 1993). It is said that Mercury rotatesthree times for every two trips around the sun, so that during Planets 3 everyalternate perihelon passage the same face points directly at the sun. “Geologically, the most remarkable features of Mercury are compressional cliffsor faults, just the sort of wrinkles that might form in the crust if theinterior of the planet shrank slightly ” (Morrison, 74, 1993). It isspeculated that it was the solidification of Mercury’s metallic core that causedthis global shrinkage. Mercury is also ” .
. . enriched in metal ordepleted of rock ” (Morrison, 74, 1993). It is also believed that some ofthe inner core of Mercury is still in a fluid state.
Scientists also believethat Mercury’s surface is made partially of silicate rock. The best way todescribe Mercury is, ” . . .
small, heavily cratered and airless “(Morrison, 71, 1993). Venus is the second closest planet to the sun and is saidto ” . . . most closely resemble Earth in size, density, and distance fromthe sun ” (Thompson/Turk, 542, 1993).
Venus is known to most scientists asthe sister planet to the Earth. It is called this because it closely resemblesthe Earth’s mass, density and diameter. The only thing different is that Venus” is shrouded in thick clouds that completely hide the surface of theplanet ” (Grolier, 1992). The surface temperature is also much warmer thanthat of Earth. Venus completes one revolution around the sun in 224. 7 days.
Thismakes the Venusian day equal to 117 earth days. It is thought that this slowrotation may be the reason why Venus has no magnetic field. Planets 4 Theatmosphere of Venus made up of 98% carbon dioxide and 2% Nitrogen. Thisatmosphere also has the presence of helium, neon and argon. This is yet anotherthing which makes Venus different from Earth.
The surface of Venus is quite abit 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 thatinundate large ares, much as the mare volcanism flooded the impacted basins onthe near side of the moon ” (Morrison, 93, 1993). One thing that differsfrom Earth is that there is no water liquid on the Venusian surface. Some of thescientific data that follows was taken out of Cattermole’s book. The meandistance from the sun is 108.
20 Km. The equatorial diameter is 12,012 Km and theequatorial 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 reddishcolor. Mars is also very much like the Earth. ” More than any other planetin 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 rotationperiod. Mars rotation period is only thirty seven minutes longer than theEarth’s.
This would explain why Mars has significant seasonal changes just asEarth does. It is believed that the Planets 5 difference between winter andsummer on Mars is even greater than on Earth. Mars is extremely hard tounderstand due to the effect of blurring that is caused by the two atmospheresof Mars. Scientists do know, however, that Mars is relatively small and thatchanges take place in the surface features when the seasons change. It is alsoknown that dust storms are prevalent and leaves the surface of Mars covered by ared 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 hundredKm per hour are required to raise the dust particles during a dust storm, andthese fast- moving particles erode structures with a sand-blasting effect “(Grolier, 1992). Therefore, the surface is basically plain-like and covered withlarge 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 degreesK. Mars also has its share of volcanoes. Most of these volcanoes are shieldvolcanoes. The surface is littered with winding channels that resemble riverchannels that have dried up over time. Scientists believe that water onceexisted and caused the formation of these channels. It is said that, ” Marsremains the best candidate for life in the solar system outside of theEarth,” and that is what makes Mars so interesting to scientists.
Jupiteris the fifth planet and is the most massive of all Planets 6 the planets in thissolar system. ” Its mass represents more than two-thirds of the total massof all the planets, or 318 times the mass of the Earth. Jupiters density isquite 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 cloudlayers. The wind activity on Jupiter is quite fierce and moves in jet streamsparallel to the equator. The weather on Jupiter is still very hard forscientists to understand. There is not enough information to truly understandhow the weather is on this planet. Jupiter is most known by the normal citizenby the rings it has.
These ” rings are very diffuse. The ring particlesmust generally be about as big as the wavelength of light, that is, only a fewmicrons ” (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 knownfor its rings and when viewed has a yellow or grayish color. The color is fromthe gaseous atmosphere and the dust particles in that atmosphere.
The atmosphereis mostly a clear hydrogen-helium atmosphere. There are also traces of methane,phosphine, ethane, and acetylene. This atmosphere is much different than that ofthe Earth’s. Saturn orbits the sun with a period of 29. 4577 tropical years.
Itis 1. 427 billion Km away from the sun and is therefore a cold planet. It has anequatorial diameter of 120,660 Km which Planets 7 makes it the second largestplanet in our solar system. The next planet is Uranus. The main problemscientists have with Uranus is that, “the lack of visible surface featuresmeans that it is difficult to measure the rotation period of Uranus”(Hunt/Moore, 388, 1983).
Uranus has an equatorial diameter of 51,000 Kmwhich is almost four times as much as Earth. The atmosphere is mostly methanegas and therefore the planet has a red tint or a blueish green color. Uranusalso 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 thegaseous planets in our solar system. Its atmosphere is much like Uranus’sbecause it is mostly helium and hydrogen. It also contains methane. Neptune hasa diameter of 49,500 Km and a mass 17. 22 times that of the Earth.
It has anaverage density of 1. 67 /cm^3 (Grolier, 1992). Neptune also has rings like itsother gaseous partners, but they are very faint. Not a great deal is known aboutNeptune. It is widely studied by scientists and that makes it an importantplanet.
The final planet, which is also the smallest, and the furthest away fromthe sun is Pluto. This planet is very hard to see therefore not a lot is knownabout its physical characteristics. Scientists do know that it has a thinmethane atmosphere. Little is known about this planet because it is so far awayfrom the Earth and the sun. Scientists are always learning new things and moredata will arise in the future. Planets 8 As one can see the planets of mostimportance are the ones closest to the sun and Earth.
Little is known about thefar off planets therefore it is hard to give them full recognition. Much isknown about Mercury, Venus, Earth, Mars, Jupiter and Saturn. The other threeplanets are not as well known as these six are. Whether more planetary systemsexist doesn’t really matter. There are still plenty of things we don’tunderstand about our own solar system.
Scientists will have their work cut outfor them in the future. Each and every planet has distinct differences and thathelps show us how truly great God is. The planets will never fully be understoodand will always be a great topic of discussion. BibliographyCattermole, P. (1995).
Earth and Other Planets. New York: Oxford UniversityPress. Grolier Electronic Publishing, Inc. (1992). Hunt, G.
& Moore, P. (1983). Atlas of the Solar System. Chicago: Rand Mc Nally & Company.
Morrison, D. (1993). Exploring Planetary Worlds. New York: Scientific AmericanLibrary. Thompson, G. & Turk, J.
(1993). Earth Science and the Environment. New York: Saunders College Publishing & Harcourt Brace College Publishers.
