Life Beyond Earth: Explorin­g Extrater­restrial Existenc­e

Although there are currently no discovery of extraterrestrial life (life outside of Earth) on other planets, studies show that life may have previously and may currently exists on other planets.

To begin, as of right now the search for life still continues. According to a chemistry article, it states, “To date though, no evidence of life – ancient or otherwise – has been found (Nina, 2018).” To explain, as of right now no life has been found. The closest galaxy to the Milky Way galaxy is Andromeda, which is 2,538,000 light years away (Scudder, 2013). Since there isn’t any vehicle, machine, or any rocket that can travel at the speed of light, there isn’t anyway, that we can get there (Scudder, 2013).

Even if a vehicle would travel at the speed of light, then it would take over 2, 000, 000 years to get there (Scudder, 2013). That means, as far as we are concerned, traveling to other galaxies and exploring them is out of reach.The farthest object that was ever sent out by humans, is a little outside of our solar system (Rothstein, 2015). Because right now no objects that humans have made have been out of our solar system, this limits to finding life through exploration to only our solar system (Rothstein, 2015). The farthest that any human have gone outside of Earth to the moon during the Apollo 17 mission in December 1972 (Rothstein, 2015).

Due to the fact that the farthest we had ever traveled is to the moon, that means we have never been able to explore other planets and this hinders our ability to find life (Rothstein, 2015). Telescopes have been used to observe other planets outside of our solar system, but these telescopes can only detect planets based on the shadows they cast (Seti, 2013).

They can’t take pictures, meaning that there is no way one can even examine the surface of planets to detect life (Seti, 2013). In other words, since we don’t have the technology needed to closely examine planets outside of our solar system, the possibility of finding life out there is significantly reduced (Seti, 2013).

To continue, now knowing that astronauts and scientist are limited to our solar system in the search for life, which planets are habitable? For Mercury, it is uninhabitable because it is either way too hot or cold to sustain life, reaching temperatures of 427 degrees celsius and as low as negative 180 degrees celsius (“Life on Mercury.” 2015). Additionally, it has no atmosphere that protects it from the harsh sun radiation, which has a detrimental effect on life and can prevent life from existing on its surfaces (“Life on Mercury.” 2015).

As for Venus, it contains 99 percent CO2, and because that carbon dioxide absorbs sunlight, the temperatures on Venus reach up to 600 degrees Celsius, making it far too hot to sustain life (UCSB Science Line, 2014). For the outer planets, gas giants don’t have any surfaces to even allow life to begin, let alone evolve (Trosper, 2014). This leaves Mars as really the only possibly habitable planet.

Not only is Mars only a few months away from Earth, making it reachable, it also has water (in the form of ice and water vapor) on its surface. None of the other planets meets these seems suitable for life (Seti, 2013). Close up images from a spacecraft, the US Mariner 4 and data collected by observation through a telescope showed that billions of years ago, Mars had the conditions to sustain life (Nina, 2018).

This included its abundance of chemical compounds necessary to establish life, liquid water, and energy from volcanic activity that allowed chemical reactions to be possible (Nina, 2018). However, the only mission that was in search of life on Mars was Viking (Seti, 2013). The viking mission included sending two spacecrafts on Mars in search of microbial life (microorganisms) in the soil (Seti, 2013).

The search found no samples of life actually existing there (Seti, 2013). As of right now, no life was found in the soil of Mars, but microbial life may still exists under its surface (Seti, 2013). However, in another mission, scientist sent the rover also known as Curiosity if Mars is habitable. Curiosity couldn’t drill deep enough into the soil to find any evidence that life can exists below Mars surfaces if any (Seti, 2).

No humans have ever reached Mars, so as of right now, no life have been discovered due to its difficulty of finding it in the first place.

Moreover, in order to explore the possible planets that can sustain life, one needs to understand what makes a planet habitable. For a planet to be habitable is it has to be in a certain area from the sun so that life could be sustained (Faris, 2018). This area should be in an area where rocky planets can form; should be close enough to the sun, but also far enough so that liquid water could be sustain; and should be out of the way from anything harmful such as a supernova (Faris, 2018).

This area is called the habitable zone (Faris, 2018). Another condition that a planet must meet to sustain life is having water (Greicius, 2017). All life and every organisms need water to survive (Greicius, 2017). For this reason, water is considered essential for life (Greicius, 2017). Additionally, because all life forms requires some sort of molecules to function, a main criteria is that planets must have some sort of atmospheric composition that have molecules for those functions (Faris, 2018).

Whether it is oxygen for respiration or carbon dioxide for photosynthesis, a planet must have molecules that life can use to survive (Faris, 2018). Not only do planets need to have molecules to sustain life, but planets should have atmospheres that absorb ultraviolet radiation from the sun and keep that heat (Farsi, 2018). Atmospheres on Earth include greenhouse gasses that protect living organisms from harmful rays from the sun (Faris, 2018).

Furthermore, with the understanding of the basic needs for life to be on planets, one can now look at the planets that may be habitable. Firstly, Kepler-186f, discovered on the April of 2014, is a planet that is in an habitable zone of another star and contains liquid water (Kramer, 2014). Then, On May 2016, researchers found seven Earth-sized exoplanets orbiting the TRAPPIST-1 dwarf star (Faris, 2018).

The densities of each planet may indicate that they are rocky planets, but some of them may contain water (Faris, 2018). On August 2016, Proxima b, a rocky planet in another solar system was discovered. It has a little more mass than Earth and can sustain liquid water on its surface (Kettley, 2017). On February 17 of 2017, another solar system with 7 Earth-sized planets were found revolving around a star (Nina, 2018).

At least three of these planets were in an area where liquid water of be on their surface without evaporating or freezing (Nina, 2018). On October of 2017, Astronomers uncovered 20 new and potentially habitable planets (Kettley, 2017). One of these major discoveries (of the potentially habitable planets) include planet KOI-7923.01 (Kettley, 2017). KOI-7923.01 is a little smaller than Earth and take 395 days to orbit (Kettley, 2017).

It is a cold tundra and is warm enough to sustain water (Kettley, 2017). All these planets possible may contain life especially since they are all habitable, but with our current technology, no life have been found on these planets.

Observations from NASA’s Kepler space telescope shows that just about every star in the universe holds planets (Wall, 2015). Out of these planets, many of them are habitable (Wall, 2015). Scientists estimates a range of 50 billion to 800 billion planets that are in the habitable zone of just the Milky Way (Faris, 2018). Of that, about one percent or around (500 million to 8 billion) are estimated to be located in the habitable zone of their respective sun (Faris, 2018).

However, inhabitable planets doesn’t necessarily contain life. Although planets may be habitable, it doesn’t mean there is actually life there. A chemistry world article states, “Mars (and other planets) being habitable, it turns out, doesn’t mean it actually has a habitat (Nina, 2018).” Planets may be habitable, but there may not be any life, but even if it is habitable, it doesn’t really have a specific area for that organisms to live there (Nina 2018).

In addition, throughout research, scientist may have found signs of life on mars. Over the past half century astronomers observed sight seasonal color variations on Mars which these variations coinciding with the availability of water, which have been interpreted as evidence for plant life (Sagan, 2015). This means that planet life could potential exists on Mars and all we need to do is search harder.

Another indication of life is a rock that came from Mars, which is known as, ALH8400 (“Life on Other Planets?”, 2002). Analysis of this these rocks shows that there may be fossilized bacteria on the meteorite (“Life on Other Planets?”, 2002). The simplest explanation of these fossils is that it Mars may have or currently inhabits bacteria (“Life on Other Planets?”, 2002).

Further, NASA's Curiosity rover has found carbon-containing organic molecules and "fixed" nitrogen, basic ingredients necessary for Earth-like life, on the Martian surface (Wall, 2015). On the other hand, although the ALH84001 rock had organic compounds that may be from fossilized bacteria, these organic compounds may be from natural processes on Mars (“Life on Other Planets?”, 2002).

Despite the fact that there may be signs that Mars contains life, there isn’t any definitive proof.

Further, a study showed that theoretically, life should exist on other planets. Throughout the universe, there are cosmic dust particles formed by stars and these particles slowly start to move away due to a wind or a massive star explosion (“Cosmic Dust Demystified,” 2016). While the cosmic dust particles float around in the universe, they start to gather together (Sagan, 2015).

As more and more cosmic dust gather together, they form a cosmic dust cloud, which is primarily made of hydrogen and helium, and a mixture of other elements. In this cloud, there will be regions that are less dense and more dense (Sagan, 2015). The less dense particles are pulled towards the denser region because of gravity (Sagan, 2015). Then as the center of this cloud condenses (Sagan, 2015).

The entire cloud will start to rotate faster and faster due to the conservation of angular momentum, which is the idea that as the mass of an object increases, the speed of an rotating object must also increase (Sagan, 2015). As more and more matter collides with the nucleus, the temperature of the cloud will continue to rise (Sagan, 2015). After millions of years, the temperature of the center of the cloud will reach about 15 million degrees (Sagan, 2015).

During the formation of planets, heavier elements sink to the center of the planet, leaving hydrogen and helium as the atmosphere surrounding the planet (Sagan, 2015). Some planets don’t have atmosphere since the star’s radiation pressure blows away this atmosphere (Sagan, 2015). Other times, planets are able to retain their atmosphere (Sagan, 2015). Since the planets formed consists of mostly hydrogen, it must also contain hydrogen compounds (Sagan, 2015).

The most abundant are hydrogen compounds of carbon, nitrogen, and oxygen (Sagan, 2015). These hydrogen compounds include methane, CH4, ammonia, NH3, and water vapor, H20 (Sagan, 2015).

The basic elements in planets result in possible formation of life. The “six main elements associated with life on Earth (include): carbon, nitrogen, oxygen, phosphorus, sulfur and hydrogen (“Exoplanet Exploration: Planets Beyond Our Solar System: Life Signs.” 2017). When hydrogen, methane, ammonia, and water vapor; which are the elements and compounds that are noted earlier; are mixed together with supplied energy, organic compounds are produced (Sagan, 2015).

Lipid membranes (layers of lipids) and DNA (formed by nucleic acids) combined to form the first cells (Carr, K.E., 2018). In simpler terms, natural elements could potentially form into nucleic acids and lipids, which become cells when they combine. Most and almost all chromosomes, genes, and enzymes, which are all important components of life, are also composed of nucleic acids and proteins (Sagan, 2015).

Everything that makes up life are made up from these common elements. A scientist known as Fox used naturally occurring elements and heat to create organic molecules that are essential to life (Sagan, 2015). In his experiment, all molecules produced were life based (Sagan, 2015). The temperatures he used to create these molecules could easily be supplied by radioactive heating of the crust of the planet (Sagan, 2015).

There is evidence that such radioactive heating is a normal part of the early evolution of all planets (Sagan, 2015). To borate, if heat is all that is required for organic compounds to be created and sustain life, that means that the possibility of life forming is highly possible (Sagan, 2015). The only thing that needed to happen was get all these molecules (the compounds that are needed to form life) together and bodies of liquid could just do that (Sagan, 2015).

In conclusion, the search for life on other planet still continues. Ever since life on Earth has originated 3.8 billion years ago, life have always been on this planet and have further developed. But because life can exist on planet Earth, why can’t it exist on other planets? After many explorations and observations of other planets, no life have yet been discovered, but with the findings of so many habitable planets and the research done, the idea of life on other planets doesn’t seem too far of a stretch.

Despite the fact that life haven’t been discovered on other planets, that doesn’t mean there isn’t any life out there, life may still exists on other planets. As we are concerned right now, new explorations such as the mission of exploring mars and the continued search of finding signs of life are to follow, but right now the fact of the matter is, no life have been discovered.

Work Cited Page

American Institute of Physics (AIP). “Cosmic Dust Demystified.” ScienceDaily, ScienceDaily, 27 Sept. 2016,

“Exoplanet Exploration: Planets Beyond Our Solar System: Life Signs.” NASA, NASA, 24 Jan. 2017, exoplanets.nasa.gov/the-search-for-life/life-signs/.

Faris, J.C. “Life on Other Planets Is Possible with These 3 Main Requirements.” Daily News, 7 Feb. 2018,

Greicius, Tony. “Our Living Planet Shapes the Search for Life Beyond Earth.” NASA, NASA, 15 Nov. 2017,

Kershner, Kate. “How Many Planets in Our Universe Could Support Life?” HowStuffWorks Science, HowStuffWorks, 8 Mar. 2018, science.howstuffworks.com/planets--universe-support-life.htm.

Kettley, Sebastian. “Are There Other Planets like Earth? Nasa Reveals Planets for Aliens and Human Life.” Express.co.uk, Express.co.uk, 7 Nov. 2017,

Khan, Amina. “The Search for Life on Other Planets Could Get a Boost from Biosignatures.” Los Angeles Times, Los Angeles Times, 25 Jan. 2018,

Kramer, Miriam. “Found! First Earth-Size Planet That Could Support Life.” Space.com, Space.com, 17 Apr. 2014,

“Life on Mercury.” Universe Today, 25 Dec. 2015,

“Life on Other Planets?” Age and Origin of the Solar System, 31 Jan. 2002, Earthguide.ucsd.edu/virtualmuseum/litu/10_1.shtml.

Nina. “Life on Other Planets.” Chemistry World, 19 Jan. 2018,

Rothstein, Dave. “What Is the Farthest in Space That We Have Gone? (Beginner).” Home - Curious About Astronomy? Ask an Astronomer, 22 June 2015, curious.astro.cornell.edu/about-us/150-people-in-astronomy/space-exploration-and-astronauts/general-questions/932-what-is-the-farthest-in-space-that-we-have-gone-beginner.

Sagan, Carl. “Life on Other Planets?” The University of Chicago Magazine, 7 Nov. 2015, mag.uchicago.edu/science-medicine/life-other-planets.

Scudder, Jillian. “What Are the Arguments for and against Aliens?” Astroquizzical, 18 July 2013, astroquizzical.com/astroquizzical/what-are-your-arguments-for-and-against-aliens.

Search for extraterrestrial intelligence (SETI). “FAQ (Frequently Asked Questions).” The Birth of SETI Institute | SETI Institute, 17 May 2013,

Trosper, Jaime. “Should We Look For Life on Gas-Giants?” Futurism, 1 May 2014, futurism.com/life-on-gas-giants/.

UCSB Science Line, 1 Mar. 2006, scienceline.ucsb.edu/getkey.php?key=1214.