The solar system consists of heavenly bodies. Among those heavenly bodies, there are nine planets which encircle the massive star called the Sun. Mars and Jupiter are two of the said planets. How are they similar? Do they manifest any differences?
The nine planets are distinguished in two categories: the inner or terrestrial planets, and the outer or jovial planets (Cameron 46). Mars is an inner or terrestrial planet. This is because inner planets are determined by their similarities to planet Earth, in terms of density and size (Cameron 46). The other planets included in this category are Mercury, Venus and Earth.
The planet Mars was named after the Roman god of war (Frey 166). It is the fourth planet. In fact, its distance from the Sun is 1.5 times that of the Earth (Frey 166-7). The mean distance between the Sun and Mars was 227,900,000 kilometers. This would then mean that Mars receives more 40 percent more sunlight in the summer when it is closest to the Sun. Its winters would also be extreme, when the Sun is at its farthest.
It is a relatively small planet, only about half of Earth’s size. Among all the other planets, Mars has more common characteristics with Earth. The rotation and inclination of the red planet resembles that of Earth’s (Frey 167). In terms of density, its composition was found to be that of rocky compounds. However, Earth and Mars are set apart by certain compounds, since the latter contains lesser content of iron but a greater amount of lightweight materials. In addition, the atmosphere of Mars is rather thin, making surface observation possible. Among the four terrestrial planets, planets Earth and Mars are the only ones with satellites. It was in 1877 when Asaph Hall discovered two bodies encircling the planet (Frey 167). Those satellites were named Phobos and Deimos. Of the two, Phobos is larger.
In the late 17th century, by observing the motion of surface features, it was discovered that the rotation period of Mars is a mere 37 minutes longer than that of Earth (Frey 167). Its rotation axis is at an angle of an estimated 24?. Hence, like the Earth, Mars also undergoes seasonal changes, thanks to the amount of sunlight it receives on a certain hemisphere. However, compared to the Earth, Mars has more severe winters and summers, as was mentioned earlier.
The size of Mars presents a difficulty in terms of the observation of its surface details from Earth. The atmospheres of both planets cause clouding, which exacerbate the difficulty in the resolution of surface features. Take the case of martian canals, for instance. In 1876, an Italian priest called Pietro Secchi initially discovered the canals. A year later, Giovanni Schiaparelli released a map wherein names where given to the “recognized bright and dark features,” which included “straight linear features” that both he and Secchi referred to as canali (Frey 167). What the two Italians wanted to convey was that what they saw were channels, but it was misinterpreted to be canals. The translation dilemma was never intended, but it offered a false notion of artificial construction (Frey 167).
The surface of Mars undergoes changes along with the seasons (Frey 167). The most eminent example would be that of the polar caps. The caps immediately shrink from its winter size the moment spring comes in. Then, when summer gives way to autumn, it resumes to its original size.
Maria is the term used to refer to the darker areas (Frey 167). These also manifest changes when seasons change. The change is in the color, as these areas become darker when the polar cap decreases. Recent studies have revealed that this change is color is attributed to the winds. These winds causes the minute, incandescent dust on the rocks to be blown away. It is a known fact through telescopic observations that dust indeed blows about in the martian surface. In addition, orange deserts are the source of dust storms, which are responsible for the planet’s signature red color.
The composition of the atmosphere of Mars is predominantly carbon dioxide (Frey 167-168). In 1940, it was already established that in Mars, oxygen and water vapor were scarce (Frey 168). It was not until much later when the composition of the martian surface was accurately determined. While oxygen and water vapor were found in small amounts, there was also the presence of nitrogen and argon. The atmospheric pressure was measured as 7.5 millibars at sea level (Frey 168).
In 1965, the flyby spacecraft Mariner 4 initially attained a closer observation of the planet Mars. According to Frey, “the carbon dioxide atmosphere was found to be exceptionally thin, only 1/100 that at sea level on the Earth (168).” It was determined that there was no magnetic field. The pictures obtained by the aircraft confirmed the existence of huge craters. However, the discovery of the Mariner 4 only observed 1 percent of the surface; the observation did not suggest that there were canals or geologic activity, nor was there evidence of life. In the end, it was found that Mars resembled Moon more than the Earth.
By 1969, there were other flyby aircrafts who produced pictures of the planet, only this time the quality of the shots were more detailed (Frey 168). The craters were again seen, but this time the pictures exhibited how eroded they are. It is a testament to the occurrence of erosion due to wind-blown dust. The thinness of the atmosphere necessitates that wind velocities need to be that of several kilometers per hour to lift particles of the ground. At these speed, it results to a sand-blasting effect, which shows how erosion occurs. Continuous erosion is proven by the featureless terrain seen on Mars. Moreover, chaotic terrain was the term used to refer to the areas of jumbled blocks (Frey 168).
Two orbiter spacecrafts were sent in the 1970s that marked an entirely new period of exploration in Mars (Frey 168). In 1971, it was the Mariner 9; in 1976, there were Viking 1 and 2. The advantage of orbiter spacecrafts to flyby spacecrafts was that the former is enabled to provide a map of the planet’s surface in its entirety, and could achieve repetitive observation throughout the change of seasons.
When the orbiter spacecrafts’ observation finally obtained a detailed description of the entire planetary surface, the similarity between Mars and the Earth and Moon was verified. In 1971, Mariner 9 saw that among the dust, there existed the peaks of four enormous volcanoes (Frey 168). The largest of these volcanoes is called Olympus Mons. It is also identified as the biggest mountain in the solar system (Frey 167). Its height is 25 kilometers; the base width is estimated to be more than 500 kilometers. Its crater, also known as the summit caldera, has a width of 65 kilometers. There are no volcanoes in the Moon, but these formations are present in both Earth and Mars. Therefore, both planets undergo the process of molten lava flowing out unto the surface, which result in volcanic formations. Nonetheless, the creation of volcanoes also set the two planets apart. The Earth’s surface is characterized by plate motion, causing the formation of volcanoes to be spread out in the ocean floor (Frey 168). On the other hand, Mars does not experience plate motion; this means that the volcanic material cannot be spread out, placing the volcanoes in one place. In fact, the volcanic formations are notably in the two regions of Mars where there is an uphill crust. Near the locations of the volcanoes, an apparent crack in the crust of Mars is found. The rift valley is characterized by several canyons, those which measures 100 kilometers at width and more than 100 kilometers at length (Frey 169). The distance was also determined to be about 5,000 kilometers (Frey 169). Now rifting is characteristic of the foundation of tectonic plates. However, the planet Mars may have had too low of a temperature to enable the existence of moving plates, ones which cause earth quakes and volcanic eruptions (Frey 169).
Despite the geologic resemblance to Earth, Mars has more similarities with the Moon in terms of appearance. The surface of both Moon and Mars are characterized by raised structures, as both have highlands and craters; their marias and plains also resemble each other.
The martian surface has been exposed to several processes that is responsible for altering its features. One of which is liquid water erosion (Frey 169). Long channels which resemble the dried up rivers were found to exist in Mars. The structure of these channels seemed similar to those of Earth’s dead streams in deserts (Frey 169). These channels are indicators of liquid water erosion. These cannot possibly be the result of lava or glacial erosion, since those two processes would produce a different kind of channel structure.
The aforementioned channels are also indicators of the drastic change in martian climate (Frey 169). According to Frey, “the low atmospheric pressure would cause any subsurface water to boil into vapor upon reaching the surface. Once in the atmosphere, it would tend to circulate to the poles and freeze out (169).” The creation of these channels necessitates a thicker atmosphere and a more humid climate; in addition, the crater counts on the channels hint that they are several hundred years old (Frey 169).
The polar regions are also proof that Mars have undergone quite a change in climate. The polar ice has a layered terrain underneath, which is only visible where erosion has made a sloping ridge eminent or caused a cut in the valleys (Frey 169). Bright and dark materials also interchange in a series of layers of about 50 meters thick. The interchanged pattern denotes the variation in deposit of dust and ice over long periods of time, and suggests that these occur due to slow changes in the polar climate (Frey 169).
It was the Viking Lander which was responsible for the first accurate details of Mars, regarding its surface and atmospheric conditions (Frey 169). In July 20, 1976, Viking 1 descended into Chryse Planitia (“plains of gold”). During and after the descent, the atmospheric structure was measured twice (Frey 169). The atmosphere was found to consist of the following elements: 95 percent carbon dioxide, 2 to 3 percent nitrogen, 1 to 2 percent argon and very little amounts of oxygen and water vapor, as was mentioned earlier (Frey 169). There is no ozone layer that could block out the ultraviolet light. There is rarely water vapor near the winter polar cap. However, where Viking 1 descended, in the summer hemisphere, it was found that water vapor is present in such a minute amount, lesser than that found in Earth’s driest places. Further observation suggested that in the past, the planet’s atmospheric pressure was higher than it is at present, as was written above regarding the dried-up channels.
Temperatures also changed depending on the time of day (Frey 169). The temperature after dark was -123° F and at daytime, it was -20º F (Frey 169). The temperature -197º F was measured during winter. Much to the surprise of the scientists, the winds were only moderate, ranging from 6 to 8 mph with occasional gusts of 30 to 40 mph (Frey 169). Another thing that added an element of surprise was the sky color. They expected a dark blue hue, but were instead greeted by a light pinkish gray sky (Frey 169). This color is due to the dust particles floating in the atmosphere.
Viking 2 descended on Mars on September 3, 1976 (Frey 169). However, it ceased operation earlier than its predecessor; Viking 1 ended its run on November 13, 1982, while Viking 2 was done by April 2, 1980 (Frey 169). Viking 2 landed on a site which was a plain, but which there were presence of rocks. This landing site was called Utopia, about 7,500 kilometers from the Chryse. In Utopia, there were many rocks and contains more water vapor than in Chryse. It is also characterized by a reddish color, due to the existence of iron oxide (Frey 169). The soil of Mars can be likened to basaltic lava, only that it has high contents of iron, but is scarce with regards to aluminum (Frey 169). The iron was found in an oxidized state; further analysis hinted that it also consists of superoxides, peroxides, and ozonides (Frey 169). These compounds were deemed responsible for the color of the martian deserts. These compounds were also said to have been formed by water vapor and its exposure with ultraviolet light.
Terrestrial planets like Mars are distinguished by their rocky compositions. Now these very same planets have lost their lighter elements due to their closeness to the Sun. On the other hand, the outer or jovial planets retain theirs. This is the reason why jovial planets are larger, and has the capacity to maintain light gases, like hydrogen, in their atmosphere (Cameron 48). One of these jovial planets is Jupiter.
Jupiter is the planet next to Mars, the fifth from the Sun. Unlike Mars, Jupiter is gigantic. In fact, it is the biggest planet in the solar system (Cameron 48). Its mass is equal to 318 times that of the Earth (Greenberg 471). If the planet is larger than it is, it could have been a star. This is because the temperature and pressure at the center of such a huge planet could cause a nuclear fusion (Greenberg 471). Jupiter is massive, but is still relatively small compared to the Sun. It is a thousand times smaller than the Sun’s size. “The planet’s fast axial rotation—once every 9 hours 55.5 minutes—causes it to be considerably flattened: the equatorial diameter is 142,800 kilometer, but the distance from the north to south pole is only 133,500 kilometers (Greenberg 471).” The distance between Jupiter and the Sun is 778.3 million kilometers, about more than 5 times the distance between Earth and Sun. It takes 11.9 years for Jupiter to orbit the Sun.
If Mars shared many similar qualities with Earth and Moon, Jupiter is also likened to another heavenly body, the Sun. It was speculated that the formation of Jupiter is the same as the Sun. This planet may have been created by a the breakdown of a early nebula, due to its gravity. If the said nebula was smaller, the compacted dust particles caused by the nebula’s cooling would have combined. The moment the “embryo” (the name for Jupiter’s core) settled in a sufficient size, its inherent gravity then drew the surrounding gases from the nebula (Greenberg 472). The composition of Jupiter is also similar to the Sun. Jupiter consists mostly of hydrogen and helium. Due to the warm temperature, underneath the atmosphere, there is no solid surface to speak of. The only thing that characterizes the surface is a steady shift from gas to liquid (Greenberg 472). In fact, one-fourth of the way into Jupiter, the pressure and temperature increases so much that the liquid turns metallic. Physicists have determined that this is the result of outer electrons being removed from molecules (Greenberg 472).
The composition of the atmosphere of Jupiter consists of ammonia, methane, and small amounts of water. Aside from these, other organic compounds are also present. In the field of astronomy, it has been long speculated that Jupiter is characterized by tri-layered clouds. It was said that the distance between the cloud layers were an estimated 30 kilometers. The lowest level was found to consist of water, while the middle layer contains ammonia and hydrogen sulfide (Greenberg 472). The highest level of clouds is mainly ammonia. Among all the clouds, the blue ones are of the lowest altitude and warmest temperature. It is followed by brown, white and red clouds, respectively. The colors can be attributed to a chemical imbalance; compounds like sulfur, phosphorus and other organic compounds are responsible for such colors (Greenberg 472). Greenberg notes that the imbalance was caused by either particle collisions, fast flow due to temperature changes of lightning (Greenberg 472). In 1979, when the two Voyager spacecrafts passed through Jupiter, it was observed that lightning do strike on the planet.
Like Mars, winds are also present in Jupiter. These winds move in vertical gushes which is parallel to the equator. The speeds are of different directions and latitudes. “The latitudes of the zonal jets correlate well with positions of broad, alternately colored bands of orange brown and whitish clouds seen by Earth-based telescopes (Greenberg 472).” Again, the colors are due to the gases, some of which ascend and descend.
The weather in Jupiter is not accurately comprehended. Storms are created and diminished, some of which last longer than others (Greenberg 472). Some storms find themselves in the middle of other strong winds and are torn apart. However, there are those that endure the storms, like the white spots and the Great Red Spot. The Great Red Spot is a massive hurricane system with a counterclockwise rotation and a revolution that occurs one in six days (Greenberg 472).
Unlike Mars, Jupiter has a magnetic field. The magnetic field that Jupiter produces is equal to that of the Earth’s core and is about 4,000 times greater than the Earth’s. “It is roughly dipolar, like a bar magnet, with its axis offset by 10,000 kilometers from the center of the planet and tipped 11º from Jupiter’s rotation axis (Greenberg 472).” As the planet turns on its axis, the magnetic field shakes with the electrically charged particles (Greenberg 472). This would then cause radio emission. There exists gas of charged particles which are tied within the magnetic field. These particles, called plasma, rotates along with the planet (Greenberg 473). The magnetic field is then referred to as the magnetosphere. This magnetosphere measures at least 20 Jovian radii away from Jupiter; this would entail an enormous area of radiation (Greenberg 473). Some of the particles found here have great speeds, reaching thousands of kilometers per second (Greenberg 473).
The satellites of Jupiter, specifically Io, gather electrons which are found perpendicular in their orbits (Greenberg 473). Io creates electric currents, which is probably responsible for the radio bursts from the direction of Jupiter that is received on Earth (Greenberg 473). The elimination of sodium and sulfur ions and atoms may also be attributed to the said particles from Io. These atoms and ions then form a cloud in the shape of a dough nut. This cloud would then encircle Jupiter in the orbit of Io. The composition of this cloud can be thrown off by Io’s volcanism and the electromagnetic exposure in the magnetosphere. According to Greenberg, “High-energy particles from the Io plasma torus spiral in along magnetic field lines to Jupiter’s atmosphere, where they stimulate the auroral light emissions seen by the Voyager spacecraft (473).”
Even though the size of Jupiter is not enough to cause nuclear burning, it is still capable of producing heat, thanks to the density of its own gravity. To this day, Jupiter generates twice as much heat as the sunlight it receives. When satellites were initially created around Jupiter, the heat it generated was much stronger. Hence, the nearer the satellite to Jupiter, the rockier its composition. The farther it is located, the colder it is. If Mars has two satellites, Jupiter has four. In 1610, Galileo discovered the four satellites of Jupiter. The satellites, which are also called the Galilean moons, are named Callisto, Ganymede, Europa and Io (Greenberg 473). These moons are considered to be a tiny solar system of sorts, because of its diversity and size (Greenberg 473). The two inner satellites are Io and Europa, which both have rocky compositions (Cameron 49). The two big outer satellites are Ganymede and Callisto, which have lower densities and indicative of ice content (Cameron 49).
Ganymede is the biggest satellite in the entire solar system. Its name was derived from the the young Trojan who was chosen by Zeus to be the god’s cup bearer (Arnett 1). Its diameter was measured to be 5,262 kilometers. It is bigger than Mercury in terms of diameter, but Mercury has more mass (Arnett 1). Io, on the other hand, is one of the rare celestial objects like Earth and Neptune’s moon Triton, which exhibit active surface features (Greenberg 473). Europa is also believed to have an ocean underneath its surface. Aside from the four Galilean moons, Jupiter has other small satellites and rings. Amalthea is the name of the largest satellite within Io’s orbit. It has an irregular shape and its surface is marked by a dark reddish appearance, and is gradually exposed to the magnetic particles of Jupiter. Jupiter has eight other satellites.
Unlike Mars, Jupiter has rings, and these rings are dispersed. Despite the planet’s size, its rings are only the size of the wavelength of light (Greenberg 473). These small particles are predisposed to the effects of Jupiter’s electromagnetism, which cause them to tumble toward the planet. This is why it is presumed that there exists many greater sized objects that encircle Jupiter which are exposed to “interplanetary micrometeoroids (Greenberg 473)” and even “volcanic ejecta from Io (Greenberg 473).” It is from these objects that the particles from the rings are derived. Jupiter is larger than Saturn, but its rings are less prominent. In fact, the rings of Jupiter are invisible from the Earth (Greenberg 472).
If Mars had spacecrafts Viking 1 and 2 to observe it, Jupiter has Voyager 1 and 2. Both spacecrafts witnessed lightning and auroras on Jupiter’s night side (Greenberg 472).
Both planets have barely anything in common, and their differences prove to be eminent. Despite being next to each other in the positioning of the planets, they are poles apart in terms of their composition and other fundamental characteristics. Mars is an inner, terrestrial planet. Jupiter is an outer, jovial planet. Mars is small, while Jupiter is the biggest planet. The former has no magnetic field, and the latter has. Mars has two satellites, Deimos and Phobos. Jupiter has the Galilean moons, and other smaller satellites. Mars has a solid surface to speak of, Jupiter has none. Mars do not have rings, Jupiter has some. The differences are plenty, but there is one crucial similarity they share: they belong to the same vast solar system that we are a part of, and thanks to modern technology, we have the opportunity to know about them.
Arnett, B. The Nine Planets. 31 Oct. 1997. 17 Dec. 2007 <http://www.nineplanets.org/ganymede.html>.
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Frey, Herbert. “Mars (planet).” Lexicon Universal Encyclopedia.
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Greenberg, Richard. “Jupiter (planet).” Lexicon Universal Encyclopedia.
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