The inner planets are relatively small and made primarily of rock and iron. The asteroids orbit the sun in a belt beyond the orbit of Mars, tumbling and sometimes colliding with one another. Made mostly of rock and iron, the asteroids may be the remnants of a planet that never formed. The outer planets, with the exception of Pluto, are much larger and made mainly of hydrogen, helium, and ice. Many astronomers believe that Pluto was and interstellar wanderer that was captured by the Sun's gravity and was not an original part of the solar system.

The orbits of the planets are ellipses with the sun at one focus, though all except mercury and Pluto are very nearly circular. The orbits of the planets are all more or less in the same plane that is called the ecliptic. The ecliptic is inclined only seven degrees from the plane of the ecliptic with and in

The planet that is closest to the Sun is Mercury. It is about 36 million-miles from the Sun and its period of revolution is 88 days. Mercury is surprisingly dense, apparently because it has an unusually iron core. With only a transient atmosphere, Mercury has a surface that still bears the record of bombardment by asteroidal bodies early in its history. Mercury passes through phases similar to those of the moon as it completes each revolution around the Sun. It has such a thin atmosphere that in a single day it reaches temperatures of up to 750*F. At night, it gets as cold as -300*F. This planet can only be seen for a short time before or after sunset. Mercury is the second smallest planet in the solar system, having a diameter of about 3,000 miles. Its mean density can compare to the earth. Its small mass and proximity to the Sun prevent it from having an appreciable atmosphere. The surface of Mercury is lots like that of the moon.

The asteroids are small rocky bodies that move in orbits primarily between the orbits of Mars and Jupiter. Numbering in thousands, asteroids range in size from Ceres, to microscopic grains. Some asteroids are perturbed, or pulled by forces other than their attraction to the Sun, into eccentric orbits that can bring them closer to the Sun. If the orbits of such bodies intersect that of Earth, they are meteors and recovered fragments are termed meteorites. Laboratory studies of meteorites have revealed much information about primitive conditions in our solar system. The surfaces of Mercury, Mars, and several satellites of the planets show the effects of an intense bombardment by asteroidal objects early in the history of the solar system. On Earth that record has eroded away, except for a few recently found impact craters.

Saturn is the sixth planet from the Sun. It is also the second largest in mass, but has the largest equatorial distance. Winds on Saturn can reach up to 1,100 miles per hour. Saturn is less dense than water by 30%. Saturn's orbit lies between those of Jupiter and Uranus, its average distance from the Sun is about 886 million miles, almost twice that of Jupiter. Saturn appears in the sky as a yellow, starlike object of the first magnitude. When viewed through a telescope, it is seen as a golden sphere, crossed by a series of lightly colored bands parallel to the equator. Saturn is covered with a thick atmosphere composed mainly of hydrogen and helium, with some methane and ammonia. Its temperature is believed to be about 270*F. Saturn rivals Jupiter, with a much more intricate ring structure and more satellites. One of Saturn's moons, Titan, has an atmosphere thicker than that of any other satellite in the solar system.

Jupiter is the first of the "Gas Giants", and the fifth planet from the Sun. Its "Great Red Spot" is its most well known feature. If Jupiter was hollow, you could fit over 1,000 earths inside it. Jupiter's orbit lies beyond the "asteroid" belt at a average distance of 483.6 million miles from the Sun. Jupiter is the first planet of the outer planets. The atmosphere of Jupiter is composed mainly of hydrogen, helium, methane, and ammonia. The atmosphere appears to be divided into a number of light and dark bands parallel to its equator and shows a range of complex features, including a storm called the Great Red Spot. Located in the Southern Hemisphere the storm rotates counterclockwise and has been observed ever since 1664. Also in the Southern Hemisphere are three white ovals that formed in 1939. According to Scientists Jupiter has no solid rock surface. Jupiter radiates about four times as much heat energy as it receives from the sun, imply

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Approximate Pages = 10 (250 words per page double spaced)