Habitability of Planets

Name: Jimmy Gao

Student ID: Z5078393

Topic13: Habitability of Planets

The topic of planet habitability, is one thats intrigued both astrologists and scientists alike. As a result, planet habitability has been closely studied in an attempt to extend and expand our knowledge on the potential existence of other habitable stellar objects, which may orbit a planetary system, such as the Solar System. Humanity has now been heavily focusing on the exploration of habitable exo-planets and its possibility, due to the environmental decay and the advent of new technologies of mankind. To ensure the viabilities of discovered planets, it’s important to provide a definition and understanding of what makes a planet habitable, consider the possibility and likelihood of habitable planets within our Galactic neighbourhood and finally if possible to research and study the discovered “habitable” planets, be it within our own galactic neighbourhood or beyond it.

Planet habitability is a reference to the measurement of a planet’s potential to develop and sustain life. In order to do so, habitable environments must provide “extended regions of liquid water, conditions favourable for the assembly of complex organic molecules, and energy sources to sustain metabolism”, outlined by NASA (D. J. Des Marais, 2008). The requirements needed to make a planet habitable can be classified into five important factors of temperature, water, atmosphere, energy and nutrients. (Dorminey, 2005)

The temperature determines a planet’s habitability, as it influences the chemical reactions for the sustainability of life. Low temperatures causes the reaction between chemicals to become slower. As a result this puts a constraint on the chemical reactions needed to create the sustainability of life. So for a planet to be habitable the required temperature is to be around 5ºC to 40ºC. (Dorminey, 2005)

Another factor which is important for a planet to be habitable is the presence of water. Water is necessary for the transportation of chemicals within and, to and from cells, as well as enabling chemical reactions between these cells. Lack of water would result in shortages of chemicals to the cell, which is responsible for providing the energy and growth requirements. In contrast, the abundance of water is not problematic, as long as the water is not too toxic. So the optimal requirements for water is for the environment of the planet to provide water that’s easily accessible and on a regular basis when required. (Dorminey, 2005)

The presence of an atmosphere is vital for a planet to be habitably viable. An atmosphere refers to the shield of a planet’s surface, used to trap heat as well as the chemicals that’s produced for life (these chemicals include nitrogen and carbon dioxide). The atmosphere blocks out radiation, as well as particles from the outer space. A planet without an atmosphere would result in the exiting of the chemicals or gas molecules essential for life. This makes the planet useless as chemical reactions and required chemicals for survival wouldn’t be feasible. Atmospheres vary in level of thickness and composition, but the suggested atmosphere a planet should have to be habitable should resemble that of Earth. The atmosphere of Earth is the most efficient as its thickness allows it to keep the surface warm as well as providing adequate protection from radiation and small to medium sized meteorites. However, planets with extremely thick atmospheres show why planets with such vast amounts of atmospheric level are inhabitable. The four giant planets within the Solar System supports this, as the surface of these planets would be comprised of mainly greenhouse gases. (Dorminey, 2005)