WHY ONLY EARTH HOSTS LIFE IN OUR SOLAR SYSTEM ? (By Sanjeevi Ramamoorthy)
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Size of the Observable Universe is > 90 Billion Light Years ( Age of Universe is only 13.8 Billion Years). We are yet to calculate the size of Total Universe. It is being estimated that there are 200 billion Galaxies in the observable universe and each and every galaxy is having more than 100 billion Stars and 99 % of these stars have at least 1 Planet in it's orbit. But, why we are still not able to find any alien life so far?What makes earth so unique to host a complicated life form like Humans?
WHAT IS LIFE?
There is no consensus among scientist community regarding the definition for Life. All we know / Assume is that All Life (as we know) had evolved from the Last common Universal Ancestor (LUCA) which is estimated to have lived approx around 3.8 Billion Years Ago.
What science doesn't know is that whether this LUCA had originated on earth or some where outside ( Interstellar Cloud / Molecular Cloud / Intergalactic Medium).
Life as we know requires following three things to get evolved on its own / from LUCA
1. One Solvent ( not Necessarily Water) in Liquid Form. ( Life on earth use water as solvent)
2. One Oxidation Agent ( Co2 / O2 / etc.,)
3. One Energy Source ( Sun / Tidal Warming / Geo Thermal Energy etc.,)
Myth of Goldilocks zone / Cir cum Stellar Habitable Zone:
Researchers hypothesized that planets in the Goldilock Zone / Habitable Zone ( particular region around star where Solar Radiations allows water to be present in liquid Form) are more likely to host complex life forms like Humans. Is it So? Then Why Mars & Venus are hostile to any kind of Life in our Solar System?
If liquid can only be present in Habitable Zone, how Titan ( Saturns Largest Moon) has ocean of Hydro Carbon on its surface) and Enceladus ( Satrun's 6th Largest Moon) & Europa ( Jupiter's Moon )have sub surface ocean of Liquid Water?
Scientists strongly suspect that Mars was once hosting life like earth ( 2 Billion Years Ago) and water was flowing on its surface like earth. Then what happened in between which made it as barren land? Will earth also face same fate like Mars?
Why Venus which absorbs less sunlight than earth ( Fact!!!!!) is so warm and hostile to life?
(Nova Documentary on Alien Planets)
SO WHAT MAKES EARTH SO UNIQUE TO HOST LIFE?
Answer to this question is to find out what went wrong with Mars & Venus.
WHY MARS HAS LOST ITS LIQUID WATER?
Planets need dense atmosphere to hold water in liquid form on its surface. But, atmosphere of Mars is less than 1% thick than earth. OOPS!!!!!!!!! Why? How Mars Lost most of its atmosphere resulting in the evaporation of liquid water from its surface?
Culprit is the Solar Wind. Solar Wind is the stream of particles ( Proton, Electron & Neutrons) released from upper atmosphere of our sun. It has the tendency to react with atmosphere of the planets and will slowly erode it away into the outer space. But, How earth Survived this fate?
Earth survived because of its magnetosphere produced by liquid lava flowing inside our earth. This magnetosphere reflects 99.99 % of solar wind into outer space protecting our atmosphere which keeps water in liquid form on our earth.
Mar's Magnetosphere is not strong enough to reflect all solar wind into outer space because of its small size compared to earth. Planet Need critical mass ( roughly 1 Earth Mass) in order to produce strong magnetic field to protect its atmosphere from dangerous Solar Wind.
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Mars Lost of most of its atmosphere to solar wind which led liquid water to either freeze or evaporate resulting in waste barren land. EARTH SURVIVED FROM THIS FATE BECAUSE OF ITS SIZE.
If Size really matters for planet Habitability, how our twin planet Venus which weighs almost same as earth has become hostile to any life form.
WHY VENUS HAS NO LIFE?
Story of Venus is totally opposite to Venus. Density of its atmosphere is 99 times thicker( 99 Bar Pr) than earths atmosphere ( 1 bar Pressure). This dense Atmosphere is strong enough to keep liquid water on its surface and its mass is also more than enough to produce strong magnetic field to protect its atmosphere from solar wind. Then Why It has become hostile for any life form?
Answer is because of "Green House Effect". Even though, it absorbs less sun light than earth, its mean surface temperature is 470 Deg C which makes the evolution of complex life almost impossible ( Microbes may still live there). How Earth escaped from this fate?
Earth escaped from this fate because of " Plate Tectonics" ( Movement of Tectonic Plates under earth surface which creates earth quakes and continental drift). These Plate tectonics help planets to trap Green House Gases ( Methane, Water Vapour, Co2) from its atmosphere into subsurface.
Recent Studies have found that "Plate Tectonics" are missing on Venus ( Reason is still unknown.). Venus had failed to trap the Green House Gases from its atmosphere due to the absence of plate tectonic activities resulting in the so called " Run away Green House Effect".
So Second Factor which makes earth so unique from other planets is its "Plate Tectonics".
But these two factors are not major factors. Hebble Telescope have found thousands of earth like planets at our Milkyway Galaxy in the Habitable Zone of the Stars. How our mother earth is different from these new planets?
PRESENCE OF JUPITER:
It seems Weird. How Planet Jupiter can help earth to host life? It can... Planets need relatively Calm Period for complex life to get evolved since process of biological evolution is very slow. Humans had evolved only before 2.5 Lakhs year ago. It took 3.8 billions of years for our earth to create intelligent life like Humans from the Last Universal Common Ancestor. If earth had collided with any bigger asteroid in this period, humans would have not evolved at all.
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History teaches us that just 10 KM size Asteroid is more than enough to kill 95 % life on earth instantly. Dinosaure which ruled this world for almost 20 crores years have been wiped out by just a small 10 KM size asteroid. ( Please read my old post titled " How Extinction of Dinosaur helped Human Evolution").
BUT WHAT IS THE ROLE OF JUPITER IN PREVENTING ASTEROIDS?
There is something called Asteroid Belt in between Mars & Jupiter. Jupiter is Very Big Planet in our solar system ( 470 times our earth). Its Huge Gravity only helps to arrest all these irregular & Huge Size ( upto 900 KM) asteroids in between mars and jupiter. In the absence of planet like jupiter in our solar system, there is lot of probability for our earth to get collided with these asteroids. Infact, our moon was created from one of such collision only.
(Asteroid Belt)
SO PRESENCE OF THE JUPITER IS ONE OF THE MAIN REASONS WHICH KEEPS US ALIVE.
SO SOME OTHER INTERESTING QUESTIONS ARE
1. Whether Moons Like Titan (Saturn's Largest Moon), Encaludus (Saturn's 6 th Largest Moon) and Europa ( Jupiter's Moon ) can host life?
2. What is the future of Earth?
3. Will earth survive Red Giant Phase of Sun?
Lets discuss in the Part 2 of this Article
.jpg)
Size of the Observable Universe is > 90 Billion Light Years ( Age of Universe is only 13.8 Billion Years). We are yet to calculate the size of Total Universe. It is being estimated that there are 200 billion Galaxies in the observable universe and each and every galaxy is having more than 100 billion Stars and 99 % of these stars have at least 1 Planet in it's orbit. But, why we are still not able to find any alien life so far?What makes earth so unique to host a complicated life form like Humans?
WHAT IS LIFE?
There is no consensus among scientist community regarding the definition for Life. All we know / Assume is that All Life (as we know) had evolved from the Last common Universal Ancestor (LUCA) which is estimated to have lived approx around 3.8 Billion Years Ago.
What science doesn't know is that whether this LUCA had originated on earth or some where outside ( Interstellar Cloud / Molecular Cloud / Intergalactic Medium).
Life as we know requires following three things to get evolved on its own / from LUCA
1. One Solvent ( not Necessarily Water) in Liquid Form. ( Life on earth use water as solvent)
2. One Oxidation Agent ( Co2 / O2 / etc.,)
3. One Energy Source ( Sun / Tidal Warming / Geo Thermal Energy etc.,)
Myth of Goldilocks zone / Cir cum Stellar Habitable Zone:
Researchers hypothesized that planets in the Goldilock Zone / Habitable Zone ( particular region around star where Solar Radiations allows water to be present in liquid Form) are more likely to host complex life forms like Humans. Is it So? Then Why Mars & Venus are hostile to any kind of Life in our Solar System?
If liquid can only be present in Habitable Zone, how Titan ( Saturns Largest Moon) has ocean of Hydro Carbon on its surface) and Enceladus ( Satrun's 6th Largest Moon) & Europa ( Jupiter's Moon )have sub surface ocean of Liquid Water?
Why Venus which absorbs less sunlight than earth ( Fact!!!!!) is so warm and hostile to life?
(Nova Documentary on Alien Planets)
SO WHAT MAKES EARTH SO UNIQUE TO HOST LIFE?
Answer to this question is to find out what went wrong with Mars & Venus.
WHY MARS HAS LOST ITS LIQUID WATER?
Planets need dense atmosphere to hold water in liquid form on its surface. But, atmosphere of Mars is less than 1% thick than earth. OOPS!!!!!!!!! Why? How Mars Lost most of its atmosphere resulting in the evaporation of liquid water from its surface?
Culprit is the Solar Wind. Solar Wind is the stream of particles ( Proton, Electron & Neutrons) released from upper atmosphere of our sun. It has the tendency to react with atmosphere of the planets and will slowly erode it away into the outer space. But, How earth Survived this fate?
Earth survived because of its magnetosphere produced by liquid lava flowing inside our earth. This magnetosphere reflects 99.99 % of solar wind into outer space protecting our atmosphere which keeps water in liquid form on our earth.
Mar's Magnetosphere is not strong enough to reflect all solar wind into outer space because of its small size compared to earth. Planet Need critical mass ( roughly 1 Earth Mass) in order to produce strong magnetic field to protect its atmosphere from dangerous Solar Wind.
Mars Lost of most of its atmosphere to solar wind which led liquid water to either freeze or evaporate resulting in waste barren land. EARTH SURVIVED FROM THIS FATE BECAUSE OF ITS SIZE.
If Size really matters for planet Habitability, how our twin planet Venus which weighs almost same as earth has become hostile to any life form.
WHY VENUS HAS NO LIFE?
Story of Venus is totally opposite to Venus. Density of its atmosphere is 99 times thicker( 99 Bar Pr) than earths atmosphere ( 1 bar Pressure). This dense Atmosphere is strong enough to keep liquid water on its surface and its mass is also more than enough to produce strong magnetic field to protect its atmosphere from solar wind. Then Why It has become hostile for any life form?
Answer is because of "Green House Effect". Even though, it absorbs less sun light than earth, its mean surface temperature is 470 Deg C which makes the evolution of complex life almost impossible ( Microbes may still live there). How Earth escaped from this fate?
Earth escaped from this fate because of " Plate Tectonics" ( Movement of Tectonic Plates under earth surface which creates earth quakes and continental drift). These Plate tectonics help planets to trap Green House Gases ( Methane, Water Vapour, Co2) from its atmosphere into subsurface.
Recent Studies have found that "Plate Tectonics" are missing on Venus ( Reason is still unknown.). Venus had failed to trap the Green House Gases from its atmosphere due to the absence of plate tectonic activities resulting in the so called " Run away Green House Effect".
So Second Factor which makes earth so unique from other planets is its "Plate Tectonics".
But these two factors are not major factors. Hebble Telescope have found thousands of earth like planets at our Milkyway Galaxy in the Habitable Zone of the Stars. How our mother earth is different from these new planets?
PRESENCE OF JUPITER:
It seems Weird. How Planet Jupiter can help earth to host life? It can... Planets need relatively Calm Period for complex life to get evolved since process of biological evolution is very slow. Humans had evolved only before 2.5 Lakhs year ago. It took 3.8 billions of years for our earth to create intelligent life like Humans from the Last Universal Common Ancestor. If earth had collided with any bigger asteroid in this period, humans would have not evolved at all.
History teaches us that just 10 KM size Asteroid is more than enough to kill 95 % life on earth instantly. Dinosaure which ruled this world for almost 20 crores years have been wiped out by just a small 10 KM size asteroid. ( Please read my old post titled " How Extinction of Dinosaur helped Human Evolution").
BUT WHAT IS THE ROLE OF JUPITER IN PREVENTING ASTEROIDS?
There is something called Asteroid Belt in between Mars & Jupiter. Jupiter is Very Big Planet in our solar system ( 470 times our earth). Its Huge Gravity only helps to arrest all these irregular & Huge Size ( upto 900 KM) asteroids in between mars and jupiter. In the absence of planet like jupiter in our solar system, there is lot of probability for our earth to get collided with these asteroids. Infact, our moon was created from one of such collision only.
(Asteroid Belt)
SO PRESENCE OF THE JUPITER IS ONE OF THE MAIN REASONS WHICH KEEPS US ALIVE.
SO SOME OTHER INTERESTING QUESTIONS ARE
1. Whether Moons Like Titan (Saturn's Largest Moon), Encaludus (Saturn's 6 th Largest Moon) and Europa ( Jupiter's Moon ) can host life?
2. What is the future of Earth?
3. Will earth survive Red Giant Phase of Sun?
Lets discuss in the Part 2 of this Article
