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One of the most fundamental questions is “are we alone?” The answer to that question would shake the foundations of our understanding of the universe and our place within it. Much of our identity is framed on the presumption that we are a peculiarity. We see ourselves as the only intelligent species on the only planet that hosts life. We therefore make ourselves the center of the universe and elevate our position. The answer to “are we alone?” would shake the foundations of religion, philosophy and biology. Finding other planets like our own would shake the foundations of astronomy and geology.
Imagine you are a member of a primitive tribe, living on the plains thousands of years ago. You’ve led a sheltered life and your comprehension of the universe is defined only by your observations and the observations of your tribe. You strike out on your own across the plains to see what else is there. Imagine seeing your first bird and having your worldview shaken by the realization that there are forms of life that can fly. You continue onward and reach the shore. Imagine seeing your first fish and having your worldview shaken by the realization that there are forms of life that can swim.
We are almost that primitive in our understanding. We define life itself based upon our limited observation of it on our planet, Earth. All we really know about life is based upon observations of the life that formed on the planet Earth. From those observations, we conclude that life involves carbon and life requires water. So, we extrapolate that if we can find places where water and complex carbon-based molecules exist, then life may also exist. That may well be short-sighted. There may be life that doesn’t need water nor carbon. But, chemistry tells us that life is more likely to be based on carbon than on any other element. Carbon is the lightest, most abundant, element with four valence electrons in a shell capable of eight. That means a carbon atom can form four covalent bonds while nitrogen can form three and oxygen can form two. Carbon can also form double bonds, allowing strong (but not so strong the molecules can't change), complex, branching molecules. This means carbon is a light and abundant element capable of forming very complex and flexible molecules. Life is complex. Life needs to be flexible to survive. Water is also viewed as a near prerequisite for life. Water is a universal solvent. It can dissolve many substances, making it extremely valuable at transporting materials in and out of living cells.
So, we look for complex carbon molecules and we look for water and we look for temperatures at which that water can be a fluid. So far we’ve found no life and few places that might sustain life. But NASA has announced the discovery of a solar system that contains seven rocky worlds, all with the potential for water on their surface. Three of those seven planets are in the habitable zone (a region around the star with an environment much like the region where our planet Earth orbits). We have found multiple places, within a single star system, where life might exist.
Not only does this give us a great specific target to direct further study, but it raises our confidence in the idea that Earth is not only not unique in its form, but that planets of similar form might actually be quite common. We have scanned an almost infinitesimally small amount of our galaxy, looking for planets similar to Earth, and yet we’ve found multiple planets that might be like Earth. Maybe they are more like Mars or more like Venus, further study will tell, but with each additional discovery of small rocky planets, abundant in carbon, friendly to water and moderately irradiated by their star, confidence in their commonality exists.
Astronomer Frank Drake proposed an equation that has become known as the Drake equation: N = R* • fp • ne • fl • fi • fc • L.
The Drake equation proposes that if we multiply the rate of formation of stars suitable for the development of intelligent life by the fraction of those stars with planetary systems by the number of planets, per system, with an environment suitable for life by the fraction of suitable planets on which life actually appears, by the fraction of life bearing planets on which intelligent life exists, by the fraction of civilizations that develop a technology that releases detectable signs of their existence, into space, by the length of time such civilizations would continue to broadcast, we would arrive at the number of civilizations in the galaxy that could possibly be detected.
Much of that equation is, today, guesswork. We have no concrete ways to determine the numerical values. We have to speculate, and speculation is qualified by our observations. This discovery, announced today, gives us better confidence in putting a more optimistic number into that middle term ne.
In our own solar system, we know of one planet that certainly is suitable for life and two planets that at one time may have been suitable for life. Today, a discovery of another solar system with between three and seven planets that may well be suitable for life.
We need to continue to make similar discoveries to become more and more confident. Someday, soon, we may actually reach the point where we are comfortable saying that a star that could potentially support life is more likely than not to also have planets that could support life. Such an revelation would dramatically change the value of N in the Drake equation, giving us more and more confidence in the idea that we are not alone. We need to develop ways to better study this system (TRAPPIST-1). In one location in the sky, we have three to seven targets that could reveal information that would radically affect multiple branches of science and possibly the way we see ourselves in the universe.
This is pretty fricking cool. With an admitted slight bit of hyperbole, this is kind of like Darwin first seeing the Galapagos. We’ve found a place to turn our sights upon. We may determine that we can find no signs of life in that system. That would be disappointing, but still immensely valuable because it is more information to enhance our understanding.
What is the significance of NASA's Feb 22, 2017 announcement? originally appeared on Quora—the place to gain and share knowledge, empowering people to learn from others and better understand the world. You can follow Quora on Twitter, Facebook, and Google+. More questions:
- Discovery of 7 Earth-Like Planets Orbiting TRAPPIST-1 : What are the planets orbiting the TRAPPIST-1 system like?
- Exoplanets: Why are there so many potentially habitable exoplanets?
- Interstellar Travel: Will interstellar travel ever be possible or practical?
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