Wiping Off all Life From Earth is Not Easy

Image credits: International Business Times/Creative Commons

An asteroid pelting towards Earth could certainly wipe all of humanity. But is this the whole truth?
The after effects of an asteroid disaster would have more devastating consequences. Occurrences of Tsunamis, earthquakes and vast clouds of dust could block the sun’s light eventually leading to crop failure, mass extinction and end the world. This could be potentially worse than the asteroid impact itself.

HOW MUCH ENERGY WOULD BE REQUIRED?

An astrophysical phenomenon must be powerful enough to boil away the Earth’s oceans for it to strip the Earth of itself. Scientists calculated the amount of energy it would take to bring all Earth’s water above the boiling point as 6 x 1026 joules which is about a million times more than total annual energy consumption by humans, or a quadrillion (1015) times the energy needed for the space shuttle to lift off.

THAT’S A LOT OF ENERGY!

It would take the energy given off by three powerful events: the impact of an asteroid the size of Vesta or Pallas, exploding stars known as supernovae and highly energetic explosions in outer space known as gamma ray bursts to really cause mass eviction of all of Earth.

It has long been thought that an asteroid wiped the dinosaurs off the face of the earth. Since then we have had more asteroid activity and hence it is one of the most familiar out of the three. By examining the asteroid impacts on Earth, we can extrapolate the data to obtain the rate of mass extinction which comes up to be 1017 years—far longer than the life of the universe. The odds of which are very, very unlikely to ever happen.

Supernovae, the massive explosions of stars release huge amounts of energy of the order of 1044 joules, which has the potential to boil our oceans. For Earth, sterilization would occur in the presence of a supernova 0.013 light years from it. This is because, the energy delivered to a planet rapidly drops off the further it is from a supernova. For Earth, the closest star (apart from the sun) is the Proxima Centauri which is 4.25 light years away thus not posing a problem.

Gamma ray bursts on the other hand have enormous amounts of energy focused into jets of radiation. For gamma ray bursts to sterilize a planet, it would have to have an origin of about 42 light years and be within the beam. Not satisfying the conditions, Earth is at no risk of being wiped out by either of the phenomenon.

EARTH’S LAST SURVIVOR

Scientists have been researching on what is known to be the toughest species inhabiting the Earth. Known as the Tardigrade or “water bear”, these microscopic eight-legged creatures can survive almost any harsh environment. Living in water, they can survive temperatures as cold as -272°C and as hot as 150°C, can live for days in the vacuum of outer space and can also withstand pressure up to six times that at the bottom of the ocean and levels of radiation thousands of times the lethal human dose.

This is due to an unknown mechanism which allows them to repair their DNA. Scientists speculate that they wouldn’t be able to survive prolonged exposure to severe heat and cosmic radiation without water—or endless time in space.

Tardigrades
False color microscopic image of a Tardigrade. Image credits: Shutterstock

Given how tiny the chances are of any of these apocalyptic events happening scientists predict it is really hard to sterilize a planet.

According to David Sloan, a cosmologist at the University of Oxford in the United Kingdom, these findings give us a chance to broaden our search for creatures on alien worlds and a range of places where we should be looking for alternate forms of life. That’s because the sturdiest organisms on Earth—not only tardigrades, but also microorganisms that thrive in extreme conditions—may resist a wide range of catastrophes, including human made ones such as global warming or nuclear wars.

With time we can figure out what phenomenon could possibly lead to mass extinction and how best to avoid the same fate as the dinosaurs!

Source Nature SpringerLink

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