Ever thought about why life is only present on Earth? In such a huge universe with millions of galaxies, why is life only detectable on Earth till now? With billions of stars, planets, asteroids and other celestial bodies around us, why are we only present on Earth? Certain characteristics make life possible on Earth.
Only because the Earth has an abundance of life, new questions regarding the possibility of life somewhere else come up. The sample size of life currently is just one. Without confirmation of aliens or life somewhere else, we can’t know what other planets have in store for us!
This article is going to talk about various questions. Why life is present only on Earth? What are the chances of life on other planets in our solar system? Can other planets also have a life? Which planets can have the existence of life?
What makes life possible on Earth?
Life on Earth requires living conditions like an atmosphere, the presence of water, a temperature worth living and many more crucial factors. Although life may be possible on other planets in our solar system or outside it, that life still hasn’t been discovered. To support life, a planet or any celestial body requires special conditions for making it habitable.
Earth provides us with everything for the existence of life. It has a suitable atmosphere with different gases like oxygen and carbon dioxide. It is also required by green plants to prepare their food. It is at the perfect distance from the Sun for us to live.
If we would have been on any other planet say, Venus, we would have been scorched to death. A little closer to any star, the water will evaporate and there ends the possibility of life. If the planet is too far from a star, it is too cold to live.
Water is a crucial ingredient for life. Any part of life requires water for its existence. Any potentially inhabited planets will have some presence of water for life. The presence of water requires all such conditions stated above.
So, all these requirements go hand in hand and are necessary for the existence of life. That is why Earth is the only known planet till now that has life, only because all these required ingredients are present here.
What are the odds of life emerging on Earth?
For Earth to have the only technological species to be ever existing in this entire universe, the probability of a given habitable planet ever developing a species must be less than 2.5*10^-24. So, for Earth to have been the only habitable planet hosting a species must be less than 1.7*10^-11. This is around 1 in 60 billion.
Is life possible on any other planets?
The enormity of the universe can’t be explained properly. We are just a part of one of the millions of galaxies named the Milky Way. This Milky Way has millions of solar systems and ours is just one of them.
With respect to this size, scientists believe that there surely will be planets somewhere in the universe that may be having life on them. But on the contrary, it is highly unlikely to form life forms of the same type as that of Earth.
Scientists have been looking forward to find life on other planets of our solar system. For the past 50 years, research has been going on. Among the most probable candidates are Venus and Mars. Missions to Venus revealed that its infamous atmosphere is made up of high percentages of carbon dioxide which make the planet too warm to support life.
With recent explorations about Mars, various situations have been analysed. But no direct evidence of life has been found and the thin atmosphere doesn’t protect the planet from Sun’s Radiations.
Are Earth-like biospheres very rare?
Having some of the living conditions on a planet is considered a great deal. Having an entire biosphere that is like that of our Earth is quite difficult. Even if it is there, the possibility of finding that anonymous planet is quite less.
Recent studies have suggested that conditions like that of Earth on any other planet might be much rarer than we thought. The study focussed on finding conditions that suit photosynthesis, which could develop further life on a planet.
For the study, the amount of light falling on different planets and stars was studied. The levels of energy that could be squeezed out were studied for the possibility of photosynthesis. Studies revealed that most of these possible lively planets were red dwarfs.
But they had super-fast winds which would wipe away their atmosphere. Other planets which could hold onto their atmospheres, were so cold that the possibility of photosynthesis was highly unlikely.
Brighter stars could continuously churn out energy for the process but their longevity is an issue. They aren’t likely to live for billions of years for the presence of complex life like that of Earth. A star half as bright as Sun could support photosynthesis but a complete biosphere like Earth would be a huge difficulty.
With this study and more studies, till now there are no such sweet spot planets that would be capable of supporting photosynthesis to turn the planet like Earth.
Are there any planets that can support life?
Although the answer to what are the chances of life on other planets in our solar system remains a mystery to us, scientists and researchers have identified some planets which could have traces of life or could possibly support it.
Here is the list of some of the planets which could have life on them.
1. Europa
The home to some of the largest oceans in the solar system, Europa is around 90 percent of the size of the Moon. Most of the water on Europa lies under the surface, but the heating due to Jupiter keeps a large amount of water as liquid. This could make life highly possible. So, Europa has water and also has heat energy from the gravitational field of Jupiter.
So, what are the chances of life on Europa? The answer isn’t clear yet because the presence of chemical ingredients for reactions isn’t confirmed yet. For more data-based researches, missions targeted for Europa are in the planning stages. European Space Agency and NASA are planning to launch a space mission for a closer look at Europa in 2022.
2. Enceladus
Jupiter, Saturn and their moons are top contenders for searching life. One of them is Enceladus. It was assumed to be an icy airless body but the Cassini mission raised flags against it. Just like Europa, it is also believed to heat from inside out due to the gravitational forces of Saturn.
The flybys conducted by the mission found water vapour, salty reservoir and organics. It is also believed that Enceladus also has a global ocean under its surface. Due to its small size, explorations from Earth isn’t much possible and no evidences of life have been found.
3. Titan
In 1980, NASA’s Voyager 1 mission visited the region around Saturn and studied its moon, Titan. Data suggested that its atmosphere was mostly nitrogen, some methane and some amounts of hydrocarbons. Titan is also supposed to have liquid water under its surface but it is much thicker than Titan. Just like other moons, it is suspected to have life but with no conclusive evidences to support it.
4. Mars
The topmost contender for the existence of life, Mars is our neighbour. It is the most explored planet in our solar system. The harsh and thin atmosphere of Mars cannot protect the planet from the radiations of the Sun. But researches and missions are at a high pace for learning more about it and whether there are chances of life on Mars or not?
5. Kepler-442b
It is around 60 percent of the mass of the Sun and orbits an orange dwarf. Around double the mass of Earth, it is roughly 1200 light-years away. It is a potential contender for supporting the process of photosynthesis.
On Earth, photosynthesising reactions occur at lights of 700-nanometre wavelength. With wavelengths of around 800 nanometres, some alien plant could possibly perform photosynthesis.
Extensive comparison of life-supporting phenomenon on different planets in our solar system
| S. No | Planets | Atmosphere | Size | Presence of Water | Presence of Heat for reaction |
| 1. | Europa | Although it has an atmosphere consisting of oxygen, it isn’t the same as that of oxygen. It is maintained by charged particles that hit the cold and icy surface. | It is 1900 miles in diameter. It is much smaller than Earth’s moon. | Largely the surface is icy but it has a deep ocean. Beneath the surface, liquid water is believed. | Due to the gravitational forces of Jupiter, heating is present. |
| 2. | Enceladus | Cassini found a layer of water vapour surrounding the moon. | It is a small moon and has a diameter of just 500 km. | Showers of water have been confirmed by the Cassini mission. | Due to the gravitational forces of Saturn, heating is present. |
| 3. | Titan | The atmosphere of Titan is majorly formed of nitrogen, with some percentages of methane and other hydrocarbons. | Titan has a diameter of 5150 km. | Titan is also supposed to have liquid water under its surface but the surface is much thicker than Titan. | Just like other moons, Titan also gets heated up due to the gravitational forces of Saturn. |
| 4. | Mars | Mars has a much thinner atmosphere as compared to Earth. More than 95% of it is formed of carbon dioxide and less than 1% is oxygen. | It has a diameter of 6779 kilometres. It is just slightly larger than half the size of Earth. | Nearly all the water found on Mars exists as ice but small quantities are also available in the thin atmosphere. | Mars gets its heat from the Sun. |
| 5. | Kepler-442b | Till now, not much is known about the atmosphere of Kepler-442b. | It is a super-Earth meaning it is greater than the Earth. it has a diameter of nearly 17000 km. | A zone on the planet is said to have liquid water on the surface. | The planet orbits a K-type star named Kepler. The planet gets its heat from this star. |
Conclusion
As we discover more worlds unknown to us, there is a possibility that we might find a planet with conditions like that of Earth. The more we would study space, the more we would get closer to the answer of ‘what are the chances of life on other planets in our solar system’. The continuous urge of humans to keep exploring and discovering new worlds will surely drive us to another planet like Earth. Till the time, all we know is that we are the only creatures and we are only present on Earth.
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Frequently Asked Questions
Q- How did life begin on Earth?
Ans – According to scientists, RNA or a similar molecule, was the first molecule to emerge on Earth. IT self-replicated and began the process of evolution which led to the formation of more life forms.
Q- Who were the first humans?
Ans – The first humans were Homo Habilis or handymen. They lived about 2 million years ago in the regions of Eastern and Southern Africa.
Q- How did early humans survive the tough life of the Ice Age?
Ans – Through the period of the Ice Age, the development of Homo Sapiens took place as humans started adapting to the harsh climate. They also developed new tools such as a needle and developed land bridges for spreading across different regions.
Q- How was the Earth created?
Ans – Earth was created around 4.5 billion years ago by the accretion from the solar nebula. Volcanic outgassing created the primary atmosphere followed by oceans. The early atmosphere had almost no oxygen.
Q- What if there was another Earth on the other side of the sun?
Ans – There can’t be any other celestial body hidden from us on the other side of the Sun as the law of gravitation would make the body known to us.
Q- Can we breathe on Titan?
Ans – Titan’s atmosphere contains 90% of nitrogen. For humans to breathe, oxygen is required. Titan is very poor in oxygen content meaning that there isn’t any oxygen available for breathing purposes.
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