Planet Pluto Research Paper

The word planet is derived from the ancient Greek word planetes, or “wanderers.” Though the visible planets of that time did appear to be wandering in the sky, the science of Astronomy has broadened this term as well as our understanding of what, in fact a planet is. By modern definition, “planet” is described as a celestial body other than a star, which orbits a star. Our Solar System orbits the center of our home galaxy, the Milky Way, and has a rich and varied structure. It consists of the Sun, four small inner planets, four outer gas giant planets, and the distant, but small planet Pluto. These planets do not wander erratically; instead they are inherently orbiting the Sun. The delineation of these planets do not end at their identification, rather they are subcategorized as
being either Terrestrial Planets or Jovian Planets, with the notable exception of Pluto, which is neither.
Terrestrial Planets are the four innermost planets closest to the sun, respectively Mercury, Venus, Earth and Mars.
These are the planets that most resemble the Earth, although Earth is the only known planet with the ability to sustain life. All four planets are rocky in composition have metal cores and solid surfaces. Due to this fact, they gain their name terrestrial from the Latin word terra, meaning "land" or "earth." All the terrestrial planets orbit the Sun and rotate on their own axes in the same direction, with the exception of Venus which rotates counterclockwise.
The Jovian planets, Jupiter, Saturn, Uranus, and Neptune are the four planets furthest from the Sun. These planets are regarded as jovian due to the “jupiterlike” qualities they possess. In contrast, they all differ greatly from the Terrestrial Planets in regards to size, composition and density. In addition, unlike the rocky, “earthy” Terrestrials, Jupiter, Saturn, Uranus and Neptune are far larger in size and far less dense which is primarily due to their elemental composition. The Jovian Planets are comprised of lighter elements and are gaseous by nature , which is why they are also known as the gas
giants.
To gain a better understanding of these nine planets, there is need to visit them individually. Earth’s Solar system has four terrestrial planets: Mercury, Venus, Earth and Mars. Terrestrial planets are those planets which are similar to Earth. As a whole, they are generally closest to the Sun; contain fewer moons, smaller in diameter, and have a thinner atmosphere. The terrestrial planets are largely composed of solid, rocky surfaces, have a central metallic core made up of mostly iron and are surrounded by silicate mantle. Additionally, terrestrial planets have canyons, craters, mountains and volcanoes. Terrestrial planets are similar in composition but vary in atmosphere, temperature and size. It is believed by some that there could have been more terrestrial planets at one time, but they have since been destroyed. To aid in this research, NASA has proposed a project that would detect terrestrial planets outside our solar system, called, Terrestrial Planet Finder .
Mercury is the closest planet to the Sun and is made up of mostly iron. It has virtually no atmosphere which contributes to it having the greatest temperature range of all the planets. On Mercury, temperatures can reach as high as 950 degrees Fahrenheit in the day and can fall as low as 120 degrees Fahrenheit at night. Mercury is only one third the size of the Earth and has an unusual rotation about the sun. It rotates on its axis one and a half times for each orbit around the sun; meaning that there are only three days in every two years on Mercury.