[dropcap size=small]O[/dropcap]ur planet earth is a little over 4.5 billion years old. First form of life aroused on earth nearly 3.8 billion years ago. With over a billion species that ever existed on earth, 99% are extinct. A series of mass extinction events have occurred throughout the history of earth. Some are even more devastating than the most well known Cretaceous-Tertiary (or K-T) which wiped out the dinosaurs from the earth. [highlight color=#ff0000 ]The timeline of humans on earth started around 0.2 million years ago and it is possible that in a distant future any mass extinction event could wipe out humans from the earth.[/highlight]
Asteroidal impacts, super volcanic eruptions, climate changes – there are many theories about the occurrence of mass extinctions that may have occurred or may occur on earth.
Here are some of the most popular theories that predict how a global catastrophe may occur naturally in future and events that could end the world –
[button color=”green” size=”big” alignment=”center” rel=”nofollow” openin=”samewindow” ]1. Asteroids[/button]
Everyday around 100 tons of meteoroids strike the earth. Some in form of dust, gravel and some in from of big rocks. These meteoroids get burnt in atmosphere and are also known as shooting stars. An extinction level asteroid could be very small as compared to earth. [highlight color=#ff0000 ]An asteroid of size 5-15 km which is negligible as compared to size of earth is enough for a global catastrophe as an asteroid that wiped the dinosaurs 65 million years ago is estimated to be of this size.[/highlight] The odds of hitting such an asteroid is very less as it hits the earth every billion years.
Asteroid Apophis, which is the size of three and a half football fields is predicted to pass extremely close to our planet in year 2029. However, there is a chance that this close pass might shift its orbit slightly which could increase the probability of hitting the earth in its next pass in year 2036. But according to the calculation, the odds are one in a million so we can rule out this possibility and feel safe.
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[button color=”blue” size=”big” alignment=”center” rel=”nofollow” openin=”samewindow” ]2. Super Volcanic Eruption[/button]
The last super volcanic eruption occurred 75,000 years ago and it changed the life on earth forever. The atmosphere was covered with ash and dust blocking the sunlight, resulting in falling of earth’s temperature by 21 degrees. Most of the human population was killed leaving just few thousands.
The Yellowstone Caldera is a super volcano situated in Yellowstone National Park in USA. This super volcano is about 45 miles wide and erupts every 600,000 years. Last time it erupted was 640,000 years ago. So it is overdue. If this super volcano erupts, one thousand cubic kilometres of lava will pour out of it. [highlight color=#ff0000 ]The whole atmosphere will be covered with the ash, making the global temperature to fall down and will bring the Nuclear Winter[/highlight]. It could truly be a mass extinction event.
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[button color=”black” size=”big” alignment=”center” rel=”nofollow” openin=”samewindow” ]3. Rogue Black Holes[/button]
Milky Way is said to contain a super massive black hole at its centre and all the stars and planets have a slight interaction with it.[highlight color=#ff0000 ] It is also believed that millions of smaller rogue black holes exist in the halo of milky way and even if one of them comes close to our solar system, it could disrupt the planetary orbits and will suck everything inside.[/highlight] These black holes are very hard or we can say impossible to detect as even light cannot escape through a black hole.
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[button color=”grey” size=”big” alignment=”center” rel=”nofollow” openin=”samewindow” ]4. Gamma Ray Burst[/button]
Credits – www.nasa,gov
Gamma ray bursts are brief intense explosions of high frequency electromagnetic radiations which give out as much energy as sun will give in its entire lifetime. Gamma ray bursts by giant exploding stars called hyper novas or by collision of neutron stars. [highlight color=#ff0000 ]If earth is caught in the path of any such event, the radiation will burn our atmosphere and will destroy the ozone layer, making our planet vulnerable to UV rays and could trigger mass extinction.[/highlight]
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[button color=”white” size=”big” alignment=”center” rel=”nofollow” openin=”samewindow” ]5. Solar Flare[/button]
Sun is on an eleven year cycle of solar activity. After every eleven years, solar activity on the surface of earth is maximum and it ejects large solar flares and CME (Coronal Mass Ejection). These solar flare causes harmless phenomenon on earth like Northern Lights or Auroras. [highlight color=#ff0000 ]But if these solar flares are large enough, they can disrupt all the communication systems and burn the power grids, leaving behind complete communication and power blackout; and in this age of technology, it will be difficult for our civilization to survive.[/highlight]
