Recently, a nearby earth-like twin was found in outer space—perhaps capable of harboring life. The planet is called Gliese 581g, and is 20 light years from Earth (about 120 trillion miles). In width, it is about 20% to 30% or so bigger than the Earth, but weighs about 3 to 4 times more. What is exciting is that the planet is inside the Goldilocks zone—meaning it is not too close to its sun (where water would boil) or too far (where water would turn to ice), but just right to have liquid water, one of the most precious substances in the Universe. We take liquid water for granted, but it is extremely rare in our solar system, found only on Earth and perhaps under the ice cover of the moons of Jupiter. Liquid water is the “universal solvent,” capable of dissolving most chemicals, including the hydrocarbon chemicals, like DNA, which make life possible.
So far, almost 500 extra-solar planets have been found in space, but almost all are unsuitable for life as we know it because of their size. Most of these planets orbit extremely close to their mother star or in highly elliptical orbits, both of which make a Goldilocks zone with Earth-like planets highly likely.
Gliese 581g will soon to be joined, perhaps later this year or next year, to scores of other Earth-like planets that will likely be found by the Kepler and Corot satellites currently in space. By analyzing the slight dip in sunlight as a planet moves across the face of its mother star, satellites may give us the best opportunity to find hundreds of earth-like twins in space. Refer to my previous blog post "U.N. to Establish Protocols for When We Make Contact With Aliens" to see photographs of the Kepler and Corot satellites.
Soon, we will have an existential shock looking at the night sky. We will wonder if anyone is looking back at us. We will look at the familiar constellations and realize that some of these stars have Earth-like twins, perhaps even liquid oceans and maybe even life. Most likely, an Earth-like planet, if it has life at all, will have microbial life. Yet that leaves open the small possibility that the planet may harbor intelligent life. If so, what might we find?