It’s The End of the World As We Know It.

Don’t worry, you should feel fine.  This isn’t going to be a doomsday treatise that keeps in line with such films as Deep Impact, Sunshine, or Armageddon. There are no reports of gamma ray bursts heading our way for me to report on; no Planet X slowly cruising towards us on a collision course like in Melancholia.  No, the end of Earth as we know it will be far less immediate than any Hollywood story currently out there or in development.  The raw deal according to a recent article published in Astrobiology by Andrew Rushby is that the Earth has spent about 70% of its lifetime in the Sun’s habitable zone and in time will be consumed by the expanding growth of the sun. But let’s not give away all of our possessions just yet.  The end of the world won’t exactly happen any time soon.

It’s now believed that between 1.5 and 2.25 billion years the Earth will be wiped out as we know it.  This will happen because as the Sun will have fused all of its hydrogen atoms into helium, and nuclear fusion will cease. Without the outward energy of the fusion in the Sun’s core, theSun will contract. This contraction will trigger the start of nuclear fusion of Helium, this new blast of energy will push the outer layers of the sun farther than before. The Sun will be considered a red giant star.  As it enlarges it will begin consuming the orbital paths of Mercury, Venus, and possibly even Earth.  Even if the Earth isn’t consumed by the Sun the oceans will boil away and the atmosphere will burn up. So, that means even on the off chance that zombies and vampires rule the Earth in the future their reign will come to an end as the Sun balloons out into the inner orbits.  Sayonara!  Nothing’s going to ride out that.

The significance of this recent study helps astrobiologists find more likely candidates for life sustaining planets.  If we take into consideration that a planet needs water to sustain intelligent life then the planet we’re looking for has to be the right size to hold an atmosphere, the right kind of density, the right kind of temperature, and of course we have to consider the age of the planet.  The exoplanet also has to exist inside what is called a habitable zone. This means the planets proximity to the star can’t be too far away or it will be too cold for liquid water to exist; it can’t be too close or it will be too hot for liquid water to exist.

Keep in mind scientists have to consider how long a planet has been within this habitable zone for it to develop signs of life: a planet forms, 1 to 2 billion years to form microscopic life, another 3 or so billion years for the development of man, add in some time for the development of technology.  Now, according to Rushby and his associates, they have to consider the long term sustainability of the star itself.  With all this information to consider it will help astrobiologists narrow down the number of planets that they consider to actually have life sustaining qualities.

Sources: http://online.liebertpub.com/doi/full/10.1089/ast.2012.0938

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