Our Earth is by far the most beautiful object in the universe discovered so far. The question that naturally comes to mind is, are there other planets like the Earth somewhere out there? While recent observations of the other planets in our Solar System have shown that those are not just bland, cookie-cutter spheres in space, they are still much less sophisticated than the Earth.
The most significant distinguishing characteristic of the Earth is the tremendous amount of liquid water. 70% of it is covered in liquid water, a must have ingredient for life. There is water everywhere throughout space, but usually not in a liquid form, and in much lower quantities.
The Earth has a hard surface to walk on. Most other planets in the universe appear to be like spheres of liquid, like Uranus and Neptune.
The Earth has just the right stuff in the atmosphere, for life on it to breathe. Mars, for example, has a rocky surface you can walk on, but its atmosphere is made of carbon dioxide, stuff we breathe out.
The Earth has just the right temperature. Whereas, say Venus, on top of an atmosphere of carbon-dioxide, also has clouds of sulfuric acid engulfing the planet. The surface temperature caused by such an atmosphere is about 900°F.
The Earth is at just at the right distance from the Sun for life to survive. Had we been a little closer, we would evaporate. Had we been a little further, we would freeze to death.
So, those were some of the factors that make the Earth very unique. The odds of finding something that would match the Earth on all of those parameters, is next to impossible. That doesn't mean scientists would stop looking, however. Rest assured, every year, billions of dollars will continue to be spent by earth's science centers, in hopes of finding an earth-like planet somewhere out there, and hopefully some sort of life on that planet.
But really, a major reason so much time and money is spent looking for an earth-like planet, is in hopes that there would also be some intelligent beings roaming that planet, who could maybe help us out with our health problems, and maybe help us in other ways. Another reason, is so we have another place to migrate to when the Earth meets its apocalypsis. From a biblical point-of-view though, the Earth was created to be unique, and it's very likely that it is the most sophisticated object in the universe. If you believe in God, you really don't need aliens either, to help you solve your problems, or to explain how life on Earth originated.
Sources:
Lisle, Jason. Taking Back Astronomy. Green Forest, AR: Master, 2006. Print.
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