essay 2 revised

The Two Different Kinds Of Planets In Our Solar System

            On Aug 24, 2006, Pluto was officially stripped of its planetary status, thus confirming it as a dwarf planet. The reason is because it did not meet the new qualifications to be a planet in our solar system. This now only leaves us with eight planets that orbit our star we call the sun. Even though all these heavenly bodies in our solar system are classified as the same thing, planets, they differ in many ways. The two types of planets in the solar system, terrestrial and Jovian planets are located in different areas in relation to the sun, have a unique composition, and have different satellites in their orbits due to the planets unique mass and gravitational pull.

One of the big differences between Jovian and terrestrial planets is the distance from the sun. All terrestrial planets are relatively much closer to the sun as opposed to Jovian planets. The outer most terrestrial planet is Mars, and it is, at the most, 154.8 million miles away from the sun, and it can be as close it is 128.4 million miles away. The closest Jovian planet is Jupiter, and that is, at the most, 506.9 million miles away and it can be as close as 460.4 million miles away (Garlick 74-114), which is still a very big difference from mars. This is just an idea of how much the distance differs. The reason is the formation of the solar system, if there is two clouds of gas and dust from the sun (one is far away and cold while the other is close and hot), the gases from the inner cloud will be lost before it collapses, but the outer cloud on the other hand will expand and collapse, in the end the terrestrial planets end up being mainly composed of metals and rock while the Jovian planets end up being mainly composed of gases and liquid (Howe). Also because the outer planets are outside the frost line, temperatures are cooler and hydrogen compounds are able to condense into ices (Wolf). This is how distance can play the difference between the two types of planets.

The atmosphere and composition also make these planets different. Venus and Mars have an atmosphere that is compose of mainly carbon dioxide which is 95% on Venus and 96% on Mars, Venus and Mars also have nitrogen which is 3.2 percent on Venus and 2.7% on Mars (Garlick 74-114), Earth is the only planet with oxygen in the atmosphere which makes up 21% of the atmosphere and 78% is nitrogen, and Mercury virtually has no atmosphere (Hamilton). Besides Mercury, carbon dioxide and nitrogen make up the atmosphere for most of the terrestrial planets. Hydrogen and helium make up most of the atmosphere for the Jovian planets, for Jupiter and Saturn it makes up 90% or more of the atmosphere, and the remaining 10% or less is helium, Uranus and Neptune have about 80% hydrogen, 15 to 18% helium and the remaining 2 to 3 % is methane (Spence 54-75). Just the composition of the atmosphere for Jovian and Terrestrial planets differs greatly. As for the rest of the composition, the main difference between these two types of planets is; Jovian planets have relatively no solid parts in the composition, it is mainly gas and liquid, and terrestrial planets are mainly rocks and other solid material (Strobel). This is how the composition and atmosphere of the Jovian and Terrestrial planets differ.

The terrestrial planets have very few satellites, otherwise known as moons. This is because the terrestrial planets lack in size compared to the gas giants, therefore, they have less of a gravitational pull on the objects around them. There are only three moons that the terrestrial planets have; Mars has two of them, Phobos and Deimos ("Astronomy 161"), while the other moon on the terrestrial side orbits Earth. The greater masses of the Jovian planets give them a much stronger gravitational pull so they tend to pick up more satellites. Jupiter has the most known satellites, it has an incredible 61 moons (Curtis), Saturn itself has 31 moons like Jupiter some of them haven’t even been named yet. Neptune has 13 moons, and Uranus has 27 moons (Robbins). All together the Jovian planets have an amazing 132 known moons, while the terrestrial planets only have 3 moons. That is a big difference and it is all because of how massive the Jovian planets are compared to the smaller terrestrial planets.

So even though all eight of these heavenly bodies in our solar system are categorized as virtually the same thing “planets,” that does not mean they are. The distance, composition, and gravitational pull on objects around them are just some of the main differences, and this is perhaps why scientist gave our eight planets two different categories Jovian and terrestrial.