Is there another Earth in the universe?

If we have enough time, could we find another planet in the universe where we could survive as humans? 

We won’t know the final answer to this question unless we actually find it.  Not finding it doesn’t mean it’s not there;  it just means we have to keep looking.  But we can look at the pros and cons of our finally making a successful search.

On the optimistic side of the ledger is the fact that space is so huge that it is almost beyond human imagination to grasp.  And it’s an incredibly dynamic place, so the possibilities are immense.  For that reason, many scientists think the likelihood of there being other planets like our Earth is high.

We are also getting much better at spotting the tell-tale signs of planets orbiting around a star.  The gravity created by a planet pull creates a slight wobble in the path of light emitted by the star which modern-day telescopes are increasingly able to spot.  Especially if the telescope, like the Hubble telescope, is sending back images from deep outer space.  So new planets are being discovered almost everyday.

Unfortunately, almost all the planets in the universe, including all the other planets in our own solar system, are decidedly inhospitable for folk like us.  They are too hot, too cold, too dry, too rocky, bombarded by lethal radiation and other objects, big and small, smashing into them.  Most critically, many are without oxygen, hydrogen, and carbon, the very fabric of all life as we know it.

The scary possibility is that Earth, even in our vast Universe, is unique:

First of all, our solar system was formed five billion years ago when the universe was already more than eight billion years old.  We are located in a fairly old part of the universe where many stars had lived and died, leaving behind that precious cache of oxygen, hydrogen, and carbon. 

Then Earth has a magnetic centre, which most planets do not have.  This isn’t just valuable because it gives us a working compass and holds our magnets onto the refrigerator door.  Most critically, it diverts many of the lethal rays of the sun around the planet.

Earth has several big brothers that protect it from the bombardment of many of biggest loose chunks of material flinging around space.  Jupiter is our biggest protector, taking the blows that would otherwise run into us and disrupt the sustained development of life.

And as we all know, Earth has a supply of oxygen for us to breathe, and an ozone layer that  is an additional protection for life forms that don’t live immersed in the sea.  Earth wasn’t made with the oxygen we breathe.  In fact, it took two billion years for it to be developed by bacteria that expelled oxygen the way we now expel carbon-dioxide when we breathe out.  Nor was the ozone level was not deep enough to protect animal life until close to half a billion years ago when fish followed plant life onto solid ground.

There are those who ask if we might be able to re-engineer a nearby planet to make it hospitable for us.  They look particularly at Mars.  Could we hang a great solar blanket behind Mars to catch the rays of the Sun, thus warming it?  If we could, and if there’s water on Mars, would it be possible to bring in enough photosynthesizing plants to create an atmosphere of oxygen for us to breathe and grow food for us to eat?    One estimate is that this could conceivably be done within the next thousand years. 

The problems would be immense, but as we shall see in the next post, it would be a doddle compared to the problems that would have to be solved if we must actually leave our current galaxy to find an alternative to Earth.