Planetary comparison and characteristics

Planetary Comparison

The Earth and other planets in the Solar System: a comparative analysis

As the only planet known wherein life exists, the Earth contains characteristics and properties that make living organisms live and thrive along with non-living elements. These properties and characteristics distinguish the Earth from other planets in the solar system. In the same way that the Earth contains properties that make it conducive for supporting human life, the other planets in the solar system have properties that hinder it from making possible for humans and other organisms from living. This paper provides a comparative analysis of the Earth and other planets in the solar system, centering the discussion on each planet's properties and unique characteristics that make it distinct from other planets.

Apart from the fact that the Earth is the third planet from the Sun and the fifth largest planet in the solar system, is an oblate spheroid planet, and has an atmosphere and bodies of water, it is also composed of five parts: the atmosphere, hydrosphere, lithosphere, mantle, and core.

The atmosphere is the gaseous envelope of the Earth. It contains a mixture of gases, wherein the principal components are nitrogen (at 78%) and oxygen (21%). The remaining 1% of the gases is composed of argon, carbon dioxide, water vapor, hydrogen, ozone, methane, carbon monoxide, helium, neon, krypton, and xenon. This gaseous mixture was primarily generated from volcanic eruptions that have evolved through the years to create other mixtures of gases. The abundant supply of oxygen was due to the existence of life on Earth: as more living organisms thrived and survived, there has been a corresponding increase in oxygen. Other gases, meanwhile, came from factories, plants, and vehicles that consume energy and later converted to other forms of gases. Throughout the years, the amount of ozone present in the atmosphere increased with the continuous and increasing use of chlorofluorocarbons (CFCs). The increased presence of CFCs in the atmosphere destroys the stratosphere, the layer which protects the Earth from the sun's ultraviolet radiation. At present, the Earth's atmosphere has been experiencing radical changes, which also led to changes in planet's climate.

The Earth's hydrosphere is mainly comprised of oceans and secondarily with other bodies of water such as seas, lakes, and rivers. The hydrosphere is composed of about 1/4400 of the total mass of the Earth.

The third, fourth, and fifth parts are lithosphere, mantle, and core. The lithosphere is composed of oxygen, silicon, aluminum, iron, calcium, sodium, potassium, magnesium, titanium, hydrogen, and phosphorus. Apart from these elements, the lithosphere also contains trace amounts of carbon, manganese, sulfur, barium, chlorine, chromium, fluorine, nickel, strontium, and vanadium. However, these elements are not extant in their free state, but as compounds, forming the rocks that make up 99.5% of the lithosphere.

While the lithosphere contains the crust and the upper mantle, the lower part of the Earth contains the mantle and core. The mantle is primarily made up of olivine, a mineral that is found in volcanoes. It is easily converted into liquefied form because of the rapid rotation of the Earth, though in general, it exists in crystallized state. The core, the last part of the Earth, is known to be the hardest, having a thickness of 2,225 km and a density score of 10. The core is composed of iron, with small amounts of nickel. The inner core, meanwhile, has greater density, at 13, and temperature, at 6,650°C (or 12,000°F).

Compared against other planets in the solar system, the Earth contains just the appropriate amounts of gases, elements, and other properties that make human and other organism life possible.

Mercury, the planet closest to the Sun, has lesser mass and volume than the Earth, at a fraction of only 1/18. However, it is as dense as the Earth, although Mercury's surface is made up of more solid mass, specifically rough, porous, dark-colored rocks. Its atmosphere is made up of sodium and potassium, which accounts for the planet's density and very thin atmosphere. It was hypothesized that the core of Mercury is made up of liquid iron compound, as a result of the presence of magnetic field.

Venus, meanwhile, exhibits a unique characteristic for being the brightest and hottest planet in the sky, with the presence of sulfur in the clouds and with a temperature of 460°C. Apart from sulfuric acid in the clouds, the planet's atmosphere is also composed of carbon dioxide. Because of its the large percentage of carbon dioxide, scientists assumed that what little water contained in Venus were evaporated and condensed into its clouds, without precipitation, using up all water resources it has. Thus, life in Venus is not possible because of the lack of oxygen and water in it.

Among the planets, it is Mars that has been found to have potential to support human life because of its numerous similarities with Earth in terms of its properties. The planet has 1/3 of the Earth's surface, which is estimated to be as large only as the Earth's dry land. It is characterized by its predominantly cold weather, with the presence of ice caps in its surface, and dust storms during times of "summer" and "spring" (when Mars is closes to the Sun). It was also believed that Mars' interior is also composed of the crust, mantle, and core. Though it was not determined whether the composition of each interior layer is similar to Earth's, it is hypothesized to have a core mainly made up of iron and nickel. However, in contrast to the Earth, the Mars did not have plate tectonics, making its surface a solid piece of mass. Its atmosphere is mainly made up of carbon dioxide, nitrogen, and argon, with trace amounts of oxygen, carbon monoxide, and water vapor.