Second Largest Planet In The Solar System example essay topic

Jupiter is the fifth planet from the Sun and the first of the five outer planets or Jovian's (gas planets) in our Solar System. Jupiter is the largest planet of them all, with a diameter of 142 000 km, it can fit 11 Earths across it's diameter, and about 1,000 inside it. Jupiter is so big that it can be seen from Earth without a telescope, and it is one of the brighter objects in the sky. Jupiter's swirling, ever changing clouds of red, yellow and orange gases have long been one of the most intriguing mysteries of space.

Only recently, through the findings of several American space probes, have astronomers begun to fully unravel the secrets of the clouds. Jupiter orbits the Sun at a comfortable distance of at least 778,000,000 km (480,000,000 mi. ), making one full rotation of the Sun every 12 (11.870) years. Every ten hours on Earth, Jupiter completes another turn on its axis, spinning more than twice as fast as Earth and making its days less than half as long as ours. This is the reason why Jupiter's clouds are ever changing; the rapid rotation causes the winds here to whirl at speeds of up to 250 miles per hour, at a hostile temperature of -250 C. Jupiter's actual surface remains somewhat of a mystery. Astronomers believe that it is composed first of a deep liquid hydrogen ocean, that covers the entire surface of the planet-probably at a depth of 10,000 miles or more.

There probably is no surface until the planet's rocky, iron core. The temperature here is believed to be a sweltering 50,000 F, a lot hotter than the outer regions! Italian astronomer Galileo Galilei first discovered Jupiter's Great Red Spot in the 17th century with his new invention, the telescope. This massive hurricane itself is three times the size of the Earth. Though the Great Red Spot does not move or change shape, it will be faint at times, and at other times it will be significantly brighter. On July 18, 1994, twenty-one pieces of the comet Shoemaker-Levy-9 collided with Jupiter, creating large red splotches in Jupiter's atmosphere-each one the size of Earth.

The enormous explosion was estimated to have the power of 6 million megatons or 6 trillion tons of TNT. "That's six hundred times the explosive power of every nuclear weapon stockpiled on Earth", said astronomer Eugene Shoemaker, one of the co-discoverers of the comet. These explosions stirred up persistent storms in Jupiter's atmosphere that could induce long lasting changes. Jupiter's 4 Largest Moons Jupiter has 16 known natural satellites, 12 of which are of small diameter. The four largest moons, known as the Galilean moons, were named for their discoverer-Galileo, who spotted them with a low-power "spy-glass" telescope in 1610. Our first close-up look at the moons came from the Voyager 1 space probe, which was launched in 1977.

Ganymede is two and one half times the size of Earth's moon and has a dark, heavily cratered surface of rocky soil, splotched with white patches of ice. It is also the second most distant of the four moons and the largest satellite in the solar system (it is also larger than Mercury and Pluto! ), with a diameter of 5276 kilometres, or 3,279 miles. Callisto is covered with craters made by giant meteors that hurtled into the moon, smashing into and melting the ice on the surface. The water formed ripples around the craters as the waves froze.

Callisto is second largest of the 4 moons with a diameter of 4,820 km (2,995 miles) and the farthest moon from Jupiter; it is also the least geologically active. Europa is just a bit smaller than our own moon (3,126 km/1,942 mi.) and looks smooth and white from afar, covered by one large ocean of ice, 40 to 60 miles thick. Despite certain dark valleys several hundred kilometres to several thousand long, filled with material from the inside of the moon -- Europa could possibly be the smoothest object of any in the Solar System. Io is the only moon in the solar system with active volcanoes, which erupt a liquid sulphur that changes colour when it cools. With each eruption, Io spews clouds of gas and dust into space. It is believed that these volcanoes are energized by the tidal effects of Jupiter's enormous mass.

Saturn Saturn, the second largest planet in the solar system, is the least dense. Its mass is 95 times the mass of the Earth and its density is 0.70 gram per cubic centimeter, so that it would float in an ocean if there were one big enough to hold it. Saturn radiates more energy than it receives from the Sun, about 80% more. However, the excess thermal energy cannot be primarily attributed to Saturn's primordial heat loss, as is speculated for Jupiter. Saturn's diameter is 120,660 kilometers (74,978 miles) but 10% less at the poles, a consequence of its rapid rotation.

Its axis of rotation is tilted by 27 degrees and the length of its day is 10 hours, 39 minutes, and 24 seconds. Saturn is composed primarily of liquid metallic hydrogen (about 80%) and the second most common element is believed to be helium. Saturn's atmospheric appearance is very similar to Jupiter's with dark and light cloud markings and swirls, eddies, and curling ribbons; the belts and zones are more numerous and a thick haze mutes the markings. The temperature ranges from 80^0 K to 90^0 K (176^0 F to -203^0 F). Winds blow at extremely high speeds on Saturn. Near the equator, the Voyagers measured winds of about 500 meters per second (1,100 miles per hour).

The winds blow primarily in an eastward direction. Saturn's Rings Saturn's spectacular ring system is unique in the solar system, with uncountable billions of tiny particles of water ice (with traces of other material) in orbit around the planet. The ring particles range in size from smaller than grains of sugar to as large as a house. The main rings stretch out from about 7,000 kilometers (4,350 miles) to above the atmosphere of the planet out to the F ring, a total span of 74,000 kilometers (45,984 miles). Saturn's rings can be likened to a phonograph, rings within rings numbering in the hundreds, and spokes in the B rings, and shepherding satellites controlling the F ring. The main rings are called the A, B, and C rings moving from outside to inside.

The gap between the A and B rings is called the Cassini Division and is named for the Italian-French astronomer, Gian Domenico Cassini, who discovered four of Saturn's major moons and the dark, narrow gap, "Cassini's Division", splitting the planet's rings. Saturn's magnetic field has well-defined north and south magnetic poles, and is aligned with Saturn's axis of rotation to within one degree. Saturn's Moons Saturn has 18 recognized moons and there is evidence for several more. The five largest moons, Tethys, Dione, Rhea, Titan, and Iapetus, range from 1060 to 5150 kilometers (650 to 3,200 miles) in diameter. The planet's outstanding satellite is Titan, first discovered by the Dutch astronomer Christiaan Huygens in 1656. Titan Titan is remarkable because it is the only known moon in the solar system that has a substantial atmosphere-largely nitrogen with a minor amount of methane and a rich variety of other hydrocarbons.

Its surface is completely hidden from view (except at infrared and radio wavelengths) by a dense, hazy atmosphere. The diameter of Titan is 5,150 kilometers (3,200 miles) and it is the second largest satellite in the solar system after Jupiter's Ganymede. Titan is larger than the planet Mercury. Titan's surface temperature is about -175^0 C (-280^0 F) and its surface pressure is about 50% greater than the surface pressure of the Earth. After the Voyager I flyby in 1980, scientists hypothesized that Titan may have an ocean of liquid hydrogen covering its surface. However, in 1990 it was shown that Titan's surface reflects and scatters radio waves, suggesting that the satellite has a solid surface with the possibility of small hydrocarbon lakes or ponds on the surface.

Uranus Uranus, the first planet discovered in modern times by Sir William Herschel in 1781, is the seventh planet from the Sun, twice as far out as Saturn. Its mean distance from the Sun is 2,869 million kilometers (1,783 million miles). Uranus's equatorial diameter is 51,810 kilometers (32,200 miles). The axis of Uranus is tilted at 97 degrees, so it orbits around the Sun nearly on its side.

Due to Uranus' unusual inclination, the polar regions receive more sunlight during a Uranus year of 84 Earth years. Scientists had thought that the temperature of its poles would be warmer than that at its equator, but Voyager 2 discovered that the equatorial temperatures were similar to the temperatures at the poles, -209^0 C (-344^0 F), implying that some redistribution of heat toward the equatorial region must occur within the atmosphere. The wind patterns are much like Saturn's, flowing parallel to the equator in the direction of the planet's rotation. Ninety-eight percent of the upper atmosphere is composed of hydrogen and helium; the remaining two percent is methane. Scientists speculate that the bulk of the lower atmosphere is composed of water (perhaps as much as 50%), methane, and ammonia. Methane is responsible for Uranus blue-green color because it selectively absorbs red sunlight and condenses to form clouds of ice crystals in the cooler, higher regions of Uranus' atmosphere.

It was also discovered that the planet's magnetic field was 60 degrees tilted from the planet's axis of rotation and offset from the planet's center by one-third of Uranus' radius. It may be generated at a depth where water is under sufficient pressure to be electrically conductive. The Uranian Rings Voyager 2 also expanded the body of information pertaining to the rings and moons of Uranus. Voyager's cameras obtained the first images of nine previously known narrow rings and discovered at least two new rings, one narrow and one broadly diffused, bringing the total known rings to eleven. It was found that a highly structured distribution of fine dust exists throughout the ring system.

The outermost (epsilon) ring contains nothing smaller than fist-sized particles. It is flanked by two small moons discovered interior to the orbit of the Uranian moon Miranda. The moons exert a shepherding influence on the epsilon ring and on the outer edges of the gamma and delta rings. All of the rings lie within one planetary radius of Uranus' cloud tops. Most of Uranus' rings are narrow, ranging in width from 1 to 93 kilometers (0.6 to 58 miles) and are only a few kilometers thick. The Uranian rings are colorless and extremely dark.

The dark material may be either irradiated methane ice or organic-rich minerals mixed with water-impregnated, silicon-based compounds. There is evidence that incomplete rings, or "ring arcs", exist at Uranus. Neptune Little was known about Neptune until August 1989, when NASA's Voyager 2 became the first spacecraft to observe the planet. Passing about 4,950 kilometers (3,000 miles) above Neptune's north pole, Voyager 2 made its closest approach to any planet since leaving Earth twelve years prior. The spacecraft passed about 40,000 kilometers (25,000 miles) from Neptune's largest moon, Triton, the last solid body that Voyager 2 will have studied. Nearly 4.5 billion kilometers (3 billion miles) from the Sun, Neptune orbits the Sun once in 165 years, and therefore has made not quite a full circle around the Sun since it was discovered.

With an equatorial diameter of 49,528 kilometers (30,775 miles), Neptune is the smallest of our solar system's four gas giants. Even so, its volume could hold nearly 60 Earths. Neptune is also denser than the other gas giants-Jupiter, Saturn, and Uranus, about 64% heavier than if it were composed entirely of water. Neptune has a blue color as a result of methane in its atmosphere. Methane preferentially absorbs the longer wavelengths of sunlight (those near the red end of the spectrum) what are left to be reflected are colors at the blue end of the spectrum. The atmosphere of Neptune is mainly composed of hydrogen, with helium and traces of methane and ammonia.

Neptune is a dynamic planet even though it receives only three percent as much sunlight as Jupiter does. Several large, dark spots are prominent features on the planet. The largest spot is about the size of the Earth and was designated the "Great Dark Spot" by its discoverers. It appears to be an anticyclone similar to Jupiter's Great Red Spot. While Neptune's Great Dark Spot is comparable in size, relative to the planet, and at the same latitude (22^0 south latitude) as Jupiter's Great Red Spot, it is far more variable in size and shape than its Jovian counterpart. Bright, wispy "cirrus-type" clouds overlay the Great Dark Spot at its southern and northeastern boundaries.

Another spot, designated "D 2", is located far to the south of the Great Dark Spot at 55^0 S latitude. It is almond-shaped, with a bright central core, and moves eastward around the planet in about 16 hours. The atmosphere above Neptune's clouds is hotter near the equator, cooler in the mid-latitudes, and warm again at the South Pole. Temperatures in the stratosphere were measured to be 750 K (900^0 F), while at the 100 millibar pressure level, they were measured to be 55^0 K (-360^0 F).

Long, bright clouds, reminiscent of cirrus clouds on Earth, were seen high in Neptune's atmosphere. They appear to form above most of the methane, and consequently are not blue. At northern low latitudes (27^0 N), Voyager captured images of cloud streaks casting their shadows on cloud decks estimated to be about 50 to 100 kilometers (30 to 60 miles) below. The widths of these cloud streaks range from 50 to 200 kilometers (30 to 125 miles). Cloud streaks were also seen in the southern polar regions (71^0 S) where the cloud heights were about 50 kilometers (30 miles). Most of the winds on Neptune blow in a westward direction, which is retrograde, or opposite to the rotation of the planet.

Near the Great Dark Spot, there are retrograde winds blowing up to 1,500 miles an hour-the strongest winds measured on any planet. Pluto Pluto, the outermost and smallest planet in the solar system, is the only planet not visited by an exploring spacecraft. So little is known about it, that it is difficult to classify. Its distance is so great that the Hubble Space Telescope cannot reveal its surface features. Appropriately named for the Roman god of the underworld, it must be frozen, dark, and dead. Pluto's mean distance from the Sun is 5,900 million kilometers (3,666 million miles).

In 1978, light curve studies gave evidence of a moon revolving around Pluto with the same period as Pluto's rotation. Therefore, it stays over the same point on Pluto's surface. In addition, it keeps the same face toward the planet. The satellite was later named Charon and is estimated to be about 1,284 kilometers (798 miles) in diameter. Recent estimates indicate Pluto's diameter is about 2,290 kilometers (1,423 miles), making the pair more like a double planet than any other in the solar system. Previously, the Earth-Moon system held this distinction.

The density of Pluto is slightly greater than that of water. There is evidence that Pluto has an atmosphere containing methane and polar ice caps that increase and decrease in size with the planet's seasons. It is not known to have water. Pluto was predicted by calculation when Percival Lowell (1855-1916) noticed irregularities in the orbits of Uranus and Neptune. Clyde Tombaugh (1906-) discovered the planet in 1930, precisely where Lowell predicted it would be. The name Pluto was chosen because the first two letters represent the initials of Percival Lowell.

Pluto has the most eccentric orbit in the solar system, bringing it at times closer to the Sun than Neptune. Pluto approached the perihelion of its orbit on Sept. 5, 1989, and for the rest of this century will be closer to the Sun than Neptune. Even then, it can be seen only with a large telescope. Comets A comet is mostly a gaseous body of small mass and enormous volume that can be seen from earth for periods ranging from a few days to several months.

A comet head, on the average is about 80,000 mi. (130,000 km) in diameter, contains a small, bright nucleus (ice and frozen gases interspersed with particles of heavier substances) surrounded by a coma, or nebulous envelope of luminous gases. As the comet nears the Sun, the particles and gases are vaporized, forming a tail as long as 100 million mi. (160 million km) The point where the comet is closest to the Sun is called the perihelion. Pushed by the solar wind, the tail streams out away from the Sun. When the comet is farthest away from the Sun, it is called the aphelion.

Dutch astronomer J.H. Oort hypothesized in 1950 that a shell of more than 100 billion comets surrounding the solar system and moving very slowly at a distance of as much as 150,000 astronomical units (AU); a passing star, however, may cause a few to be launched closer to the Sun. In 1951, G.P. Kuiper proposed a region of minor planets just outside Neptune's orbit as a source of comets with short orbital periods.