Terrestrial and Jovian Planets Our solar system contains nine planets, which are broken down into 2 classifications known as terrestrial planets and jovian planets. The terrestrial planets are composed primarily of rock and metal. They also generally have high densities, slow rotation, solid surfaces, no rings, and few satellites. These planets include Mercury, Venus, Earth, and Mars. On the other hand, the jovian planets are composed primarily of hydrogen and helium.
These criteria would admit a few of the larger asteroids and probably some of the Kuiper belt objects as well, but adding a requirement for a planet to have a minimum diameter of 1,000 km would remove the larger asteroids from contention while retaining Pluto. Below are some brief reasons as to why Pluto may not be considered a planet with my rebuttal. Pluto is small compared to the other planets. Pluto is about half the size of the next smallest planet, Mercury. However, there is no scientific reason whatsoever to pick the size of Mercury as being the size of the smallest object to be called a planet.
Mercury Named for the wing-footed messenger of the Roman gods, Mercury races around its orbit at a dizzying speed of 30 miles (48 kilometers) per second, making the Mercurial year only 88 Earth days long. In contrast, one rotation around its axis—or a single day—takes almost 59 Earth days. Geology Mariner 10 gave us a wealth of information about Mercury when it approached the planet in 1974 and 1975. Because Mercury has no water and barely any atmosphere, no erosion has taken place on its surface. We see Mercury much the way it was soon after it formed.
Neptune, the planet farthest from the sun in our star system, is only 30 AU from the sun, compared to the 650 of the newly discovered planet. The binary star formation theory deals with this problem of ... ... middle of paper ... ...earth. References Bailey, V. (2013, 12 05). Ua astronomers discover planet that shouldn't be there. UA News.
Many scientists theorize that Pluto might actually have once been a moon of Neptune. It is believed that Pluto originally came from outside of our solar system and was accidentally caught in the Sun’s gravity, pulling the dwarf planet into our solar system. So, Pluto would have been far from the typical classified planet, especially when it comes to the size. Therefore Pluto’s status of dwarf planet comes a great deal from its small size, so ... ... middle of paper ... ...it which brings a literal definition to dwarf planet. As well, the orbit of Pluto is angled, ovular, and it crosses the path of other objects, something a true planet would not be able to do.
However its rotation takes 243 Earth days, making a day longer than a year (“Planet Venus Facts”)! Other than Uranus, Venus is the only planet to rotate from East to West (“Planet Venus Facts”). Venus’s atmosphere is extremely dense (Feather and Zike 77). Many of the clouds surrounding the small planet are composed mainly of sulfuric acid (“Planet Venus facts”). The air itself is 96% carbon dioxide and oxygen has not been detected and the pressure on the surface is 92 times that of Earth’s atmosphere (Coffey, “Atmosphere of Venus”).
Saturn is the 6th planet in order distance from the sun. It cannot approach the planet Earth closer than 1,190,000,000 kilometers. Its brightness is due to its large size. Saturn's equatorial diameter is 120,660 kilometers, but its globe is kind of flattened, and the polar diameter is only 108,000 kilometers. The mass of Saturn is 95.17 times that of the Earth, and the escape velocity, which is the velocity which once attained it will enable the object to "coast" away from the planet, is 32.26 kilometers per second, more than three times that of the Earth.
Pluto Come wander with me, she said, Into regions yet untrod; And read what is still unread In the manuscripts of God. - Longfellow Although Pluto was discovered in 1930, limited information on the distant planet delayed a realistic understanding of its characteristics. Today Pluto remains the only planet that has not been visited by a spacecraft, yet an increasing amount of information is unfolding about this peculiar planet. The uniqueness of Pluto's orbit, rotational relationship with its satellite, spin axis, and light variations all give the planet a certain appeal. Pluto is usually farther from the Sun than any of the nine planets; however, due to the eccentricity of its orbit, it is closer than Neptune for 20 years out of its 249 year orbit.
The size of Venus is very much like that of Earth, just a little bit smaller (Coffey…Size). The color of Venus is actually a bright white color, most of the yellowish orange pictures you see are false color images used to show the features of the surface (Cain). “Scientists say that no one really discovered Venus since it is visible to the naked eye”, due to it being the second brightest object in the sky (Discovery). So there isn’t an actual date for its discovery. In 1610 Galileo was the first to observe Venus, but ancient people were most likely aware that it was there because it is the first “star” you see before sunset and the last “star” you see before sunrise (Galileo).
Mercury Mercury is the second smallest planet in the solar system and is closest and innermost planet to the sun. Did you know that the sun warms Mercury? It is 36 million miles from the sun and takes 88 days to circle it, and Mercury takes 59 Earth days to spin once on its axis. But Mercury does not have any gases. Mercury is very hot in its surface, the temperatures range from: 430 degrees Celsius through 130 degrees Celsius.