Is Earth Unique or Is Life Common Across the Universe?

illustration of gliese 581g

NEW YORK – The discovery of Gliese 581g, an alien planet orbiting in the habitable zone of its parent star, has added new fuel to the debate over the uniqueness of Earth and whether life exists elsewhere in our universe. The Gliese 581g finding ignited the scientific community because the exoplanet was found in the habitable zone of its star – a region where a planet's range of temperatures could sustain liquid water on its surface. This area is also known as the Goldilocks zone, because surface temperatures are neither too hot nor too cold, meaning liquid water and other potentially life-supporting conditions could be found on the exoplanet.  "On Earth, where there is liquid water, there is life," 

In order to determine the conditions required to nurture and sustain life on other planets, understanding our home planet is a good place to start. 

So, is life unique to Earth, or could it be common in our universe? And if it is common, how close are we to finding extraterrestrial life? 

While some panelists disagreed on whether Earth itself is unique, they were more readily able to agree that finding some form of alien life – be it microbial or otherwise – is only a matter of time.
space.com