In the Comfort Zone

The third planet from the sun, our Home; what made it so special? So ideal for the plethora of simple and complex organisms including us who can contemplate on “what makes Earth special”?


We have an atmosphere with right density, right pressure; the right temperature, and an ideal fluid to support life. But, is that all that makes Earth the right place for life to emerge? There is just one more essential parameter (which has made the other parameters possible). The distance from sun! A little nearer it would have been too hot, a little further too cold. Doesn’t that imply that for any given star if planets or moons happen to fall in this right place , then life might evolve on them? This region is called the Habitable zone or Goldilocks zone (after the same Goldilocks from “Goldilocks and three bears” who would have been part of your bedtime story as a kid) . But its not just the correct spot from a star that’s is essential for supporting life, but also the right location in the galaxy (galactic habitable zone). Near enough to the galactic center to have enough metals (to make it a rocky planet like ours) and far enough to remain protected from the high frequency radiations that is lethal to life forms similar to us (carbon based).

What makes such places hospitable? Simple! The perfect (or near perfect) temperature which can support liquid water, the one fluid that has changed or rather written the history of our planet. So when looking for earth-like life forms, it is such zones in the universe that should be the starting point for the search.
The above statement may be an oversimplification. For even on our own planet we have come across creatures called the extremophiles, living in deep hot sulphur filled vents, underneath ice sheaths in Antartica, in the darkest regions of ocean where no light penetrates; where one would have never imagined a possibility of existence of life. But even in these organisms survival has been possible because of liquid water( they have developed ways to keep water in liquid state within them).
Scientists studying the possibility of extraterrestrial life are trying to find and explore these comfort zones, where conditions seem to be like that on earth. Recently existence of a rocky planet in such a habitable zone has been observed for one of the close star (just 20 light years away) called Gliese 581.


The fourth planet from the star lies in the outskirts of this region. Intially the planet Gliese 581 d was thought to be too cold for supporting life, but around April 2009 it was confirmed that it lies on the border of habitability. All it needs to do now is make some green house gases, raise its temperature to become suitable for supporting life.

So as Goldilocks famous line goes (and reason why the name was given):
"This porridge is too hot," Goldilocks exclaimed.
So she tasted the porridge from the second bowl.
"This porridge is too cold."
So she tasted the last bowl of porridge.
"Ahhh, this porridge is just right!" she said happily.
And she ate it all up.
It has to be ‘just right’ nothing less, nothing more.