Recently, scientists announced the discovery of a planet only four light years away from Earth located in the Alpha Centauri system. The planet is called Proxima Centauri, and it may be habitable. This discovery, along with recent discoveries of other potential exoplanets that can harbor life has led many leading astronomers to come to the conclusion, that we likely are not alone in the universe.
The estimates of potential earth-like planets vary among astronomers and exobiologists (those who study extraterrestrial life). NASA estimates conclude that there are probably more than 100 Billion Earth-like planets based on the assumption that our universe has 500 billion billion stars similar to our own. That figure contemplates conditions nearly identical to Earth for life to evolve on these planets. Evidence derived from new powerful telescopes, including Kepler’s exploration of the Milky Way, and various space probes in our own solar system have shown that the water is more common place that thought and the organic building blocks of life are abundant.
These estimates are generally based upon a formula of probability created by Astronomer Dr. Frank Drake in 1961. His “Drake Equation” sought to arrive at an estimate of the number of active, communicative extraterrestrial civilizations in the Milky Way galaxy. It was based on: N = The number of civilizations in The Milky Way Galaxy whose electromagnetic emissions are detectable. R* = The rate of formation of stars suitable for the development of intelligent life. f = The fraction of those stars with planetary systems. n = The number of planets, per solar system, with an environment suitable for life. f = The fraction of suitable planets on which life actually appears. f = The fraction of life-bearing planets on which intelligent life emerges. f = The fraction of civilizations that develop a technology that releases detectable signs of their existence into space. L = The length of time such civilizations release detectable signals into space.
Astronomers at the University of Auckland claim that there are actually around 100 billion habitable, Earth-like planets in the Milky Way. Multiplied by the 500 billion plus galaxies in the universe, they estimate around 50,000,000,000,000,000,000,000 (5×1022) habitable planets, or 50 sextillion in the universe. Of course, forms of life could potentially evolve without Earth-like eco-systems would exponentially change that estimate to even a greater number.
There are a variety of projects dedicated to the Search for Extraterrestrial Intelligence (SETI) now scanning space with state-of-the-art sensitive optical and acoustic technologies. Also, an interesting approach called Gravitational Microlensing is being used for detection of planets using techniques that measure the bending of light emitted by a star as a result of gravity from orbiting objects. With investments, innovation, and new tools, SETI is advancing rapidly in focus and function.
There are those who say with all the possibilities of life out there – where is it and why have we not yet discovered it? This is commonly called the “Fermi Paradox” based on scientist Enrico Fermi’s noting of the contradiction between the high probability that life that is predicted to be in our universe, and the lack of evidence that advanced life exists anywhere else but Earth. But as such a young civilization that only discovered electricity in a very recent era, there is not really much of a paradox to entertain. We are just at the doorstep of exploration and cannot not expect to know what we do not know yet. Man’s real quest for the stars has really just begun .
As mankind’s technology and computing capabilities continue to grow, so will our ability to explore in greater detail the expansiveness of space and the multitude of galaxies. What was yesterday’s science fiction is now today’s reality. Our imaginations are our only real limits. Someday, we may even have the capacity to travel beyond our dreams as humans, perhaps as cyborgs or replicating robotic probes. The discovery of Proxima Centauri in another small step is our pondering and understanding of what may be out there as we peer among the night sky.