The Outer Planets

The Outer Planets

Danica Male

Physical Science

Dr. Khilstrom

October 22, 2012

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The universe is a huge and complex place. Our galaxy alone is comprised of many different planetary objects. Our Earth is special in that it is the only place that we know of where life exists. However, there are still many interesting facts about the other components of our galaxy. One of the most fascinating parts of our galaxy, is our planets. We have eight major planets in our solar system. These eight planets are separated into two parts, based on their characteristics. The first four planets are the inner planets. These are Mercury, Venus, Mars, and Earth. The last four planets make up the outer planets and are comprised of Jupiter, Saturn, Uranus, and Neptune. The four outer planets are interesting because they are so unlike our earth. These are classified together because of their size, gaseous makeup, and low densities.

The four outer planets all have similar compositions. One thing that they have in common is their size. These planets are the largest by far, with their cores being larger than most of the inner planets themselves. These rocky, metallic cores were formed and “swept up” gases. The cores would attract gases (mainly hydrogen and helium) from early planetary nebula until the sun ignited. Once the sun ignited, it is thought that the solar winds blew away the rest of the gases (Hewitt, Suchocki, and Hewitt 718). Even with their massive size, the planets are not very dense because they are comprised mostly of gases. These planets all also have a ring system. Some of the planets rings are more visible than others, for example Saturn, however even if harder to see; all of these planets have a ring system.

Jupiter is the largest planet. It was the first to develop and therefore had the longest amount of time to collect gases before the sun ignited. It is also the brightest of all

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the stars, and shines yellow. It rotates at an extremely fast rate and spins around its axis in about ten hours. However all parts do not rotate at the same time. The equatorial regions spin faster than the rest, but only by a few minutes (Hewitt, Suchocki, Hewitt 719). The atmospheric pressure of Jupiter is one million times that of Earths, and is also eleven times greater in diameter than the Earth. One surprising fact is that even though Jupiter is so big in comparison to the Earth, it is only about three hundred times the mass of Earth. For such a big planet, it would be easy to assume that the mass was significantly greater than this, however since Jupiter is made up of mostly gases, it’s density is very low. Its core is where it gets most of its weight which is fifteen times the size of the earth and composed of nickel, and iron primarily. Jupiter has a large magnetic field due to the level of electron conduction that occurs in its liquid hydrogen atmosphere. Jupiter also had over sixty moons. The largest of these moons is Europa. Europa has an ice surface, but warm water underneath that. Because of this composition, and other features of this moon, it is speculated that if life were to be found anywhere else; it would be here (Hewitt, Suchocki, Hewitt 719).

The second largest of the outer planets is Saturn. Saturn is the second largest and the second heaviest next only to Jupiter. It is also a very bright planet, shining brighter than all but two stars. It’s diameter is ten times that of the Earth, and it weighs one hundred times Earth. Saturn is made up of primarily hydrogen and helium gas, and has the lowest density of all planets. Saturn’s density is less than waters, which means that if there were a bathtub large enough, Saturn would float (Hewitt, Suchocki, Hewitt 720). Saturn also spins at a rapid rate. It spins on its axis in about 10.2 hours. Because of its

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low density and its rapid spin, it produces polar flattening. This is why Saturn appears to be more oblong than it is round. Saturn is special in the sense that its ring system is extremely pertinent. It is the easiest to see of the ring systems, and therefore makes Saturn appear differently than the rest of the planets. There are 4 distinct rings; although in total there are more, but they are harder to distinguish. These concentric rings are made up of rocks and ice. These rocks and ice are believed to be the remains of a moon that never formed. These rocks and ice are also special because they maintain their own orbit, separate from Saturn. Saturn has over fifty moons, with its largest moon being Titan. NASA landed on Titan and the photos show a landscape very similar to that of the Earth’s. However, when more closely investigated it was found that although it appeared the same, the materials were very different (for example lakes are filled with liquid methane instead of water). For this reason, it is expected that no life form exists here.

Uranus is the third outer planet. This planet can barely be seen by the naked eye, and therefore wasn’t even discovered until 1781. Uranus has four times the diameter of Earth and is barely denser than water. Using the bathtub analogy again, Uranus would not be able to remain afloat. One thing that makes Uranus unique is it’s strange tilt. Uranus is tilted 98 degrees perpendicular to its orbital plane which means that is lies on its side (Hewitt, Suchocki, Hewitt 721). There is no internal source of heat on Uranus which makes the planet extremely cold, and therefore not a good source for life. The discovery of Uranus actually led to the discovery of Neptune through its perturbations.

Neptune is the last of the outer planets. Its diameter is 3.9 times Earth’s, 17 times as large, and 1/3 as dense. It is made up also of primarily hydrogen and helium, but also

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some methane and ammonia which gives it a blue glow (Hewitt, Suchocki, Hewitt 721). Neptune has crazy wind power. This planet has the strongest winds in all of the solar system that travel at 2,100 km/hr. It seems puzzling to scientist that a planet so cold can produce such strong winds but it is speculated that the winds are so strong due to a lack of friction. The cold temperature coupled with the flow of fluid gasses may reduce friction enough that it is easier to generate such strong winds (Cain, Universe Today). There has only been one mission to Neptune from the Voyager 2 in 1989. There are tentative plans to return to Neptune, although nothing has been firmly put into place. If they were to return to Neptune the Neptune Orbiter would launch in 2016 and take 14 years to travel to Neptune. Once there it would be sent into orbit to study weather, moons, and the ring system. Although they have been talked about, it is still not a guaranteed mission. (Cain, Universe Today).

One peculiar case is the case of Pluto. Pluto used to be the 9th planet is our solar system, but within the last decade it has been demoted. It is no longer considered to be a planet, but dubbed a “dwarf planet”. The official definition of a planet is an object that orbits the sun, and it large enough to become round due to the force of it’s own gravity, and it must dominate the neighborhood around it’s orbit. Pluto was demoted because it doesn’t dominate its “neighborhood”. Pluto has a moon called Charon which is half the size of Pluto. For all other planets, the planet is significantly larger than it’s surrounding moons. Pluto’s orbit is also messy. Other planets “sweep up” asteroids and comets, but Pluto does not. The qualifications of a dwarf planet are better met by Pluto, and the

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qualities needed to be considered a true planet are very rare. It is not thought that another true planet will be discovered too easily (Inman, National Geographic News).

Whatever the case, the planets are astounding. Although all of these planets have things in common, they are also very different and each unique. It is great to learn about the planets. I feel humbled learning about things that massive and far away. It makes my life feel slightly insignificant, but also grateful to live in this world like I do. I feel very blessed to call myself a child of this awesome Creator that we worship. To end with a quote by Louis Pasteur that sums up my feelings about the subject, “The more I study nature, the more I stand amazed at the work of the Creator.”

Works Cited

1. Hewitt, Paul G., John Suchocki, and Leslie A. Hewitt. Conceptual Physical Science. Boston: Pearson, 2012. Print.

2. Inman, Mason. "Pluto Not a Planet, Astronomers Rule." National Geographic. National Geographic Society, 24 Aug. 2006. Web. 20 Oct. 2012. <http://news.nationalgeographic.com/news/2006/08/060824-pluto-planet.html>.

3. Cain, Fraser. "Interesting Facts About Neptune." Universe Today. N.p., 8 Dec. 2008. Web. 20 Oct. 2012. <http://www.universetoday.com/21999/10-interesting-facts-about-neptune/>.