So far, we have yet to find life beyond Earth, but we’re still searching.
Are we alone?
The search for life beyond Earth is just beginning, but scientists have already found promising clues. Many planets in our galaxy have similarities to Earth. But we still don’t know for sure if they harbor life.
For millennia, humans have wondered about the stars. Now, we know that the stars beyond our Sun are home to many planets, some of which are similar in size to Earth; this raises many new questions: Which of these planets harbors life? How did life get started on Earth? And how long will it last?
Where is everybody?
The universe’s eerie silence has been dubbed the Fermi paradox. Physicist Enrico Fermi famously asked, “Where is everybody?” Even at slow travel speeds, the billions of years that the universe has existed should have allowed intelligent, technological lifeforms to traverse the galaxy. So why is the cosmos so quiet?
In the past two decades, exoplanet discoveries have filled in a few of the terms in the much-debated Drake equation, which could one day tell us how many intelligent civilizations we can expect to find. However, most of its terms remain blank, such as the fraction of planets with life, with intelligent life, and with detectable technology. Nevertheless, the equation suggests that we might one day arrive at an answer, which is at least a little more hopeful than Fermi’s silence.
How will we know if we’ve found life beyond Earth?
JWST, launched in 2021, could be the first to peer into the atmospheres of Earth-sized exoplanets. JWST or a similar spacecraft in the future could pick up signs of an atmosphere like our own, such as oxygen, carbon dioxide, and methane. These gases are a strong indication of possible life. Future telescopes might even be able to detect signs of photosynthesis, the process by which plants convert light into chemical energy or gases or molecules that suggest the presence of animal life. The presence of atmospheric pollution on an exoplanet could be a sign of intelligent, technological life.
The best we may be able to do is estimate the probability of life on other planets. However, an exoplanet with a 95% probability of life would be a game-changer of historic proportions. It would provide strong evidence that we are not alone in the universe. And it would open up a new chapter in our search for extraterrestrial life.
What are the methods we can use to find life beyond Earth?
In our neighborhood, we might find life beneath the Martian surface or in the dark, subsurface oceans of Jupiter’s moon, Europa. We might also be able to eavesdrop on the communications of extraterrestrial civilizations or capture evidence of “technosignatures,” which are traces of technology that could be detected from afar.
Technosignatures could include things like artificial radio emissions, pollution, or even the presence of megastructures such as Dyson spheres. However, these are all long shots.
The most likely way to find life beyond Earth is to look for it in the atmospheres of exoplanets. By splitting up the light from these atmospheres into a rainbow spectrum, we can read it like a bar code and identify the gases and chemicals present. This method, called transit spectroscopy, could reveal the presence of gases linked to life, such as oxygen, carbon dioxide, and methane.
Where should we search for extraterrestrial life?
Astronomers have confirmed the existence of over 4,900 exoplanets in our galaxy, and they believe that there are likely trillions more.
One of the best tools that scientists have to narrow down the search for habitable worlds is the concept of the habitable zone.
The habitable zone is the Goldilocks zone, where temperatures are just right for liquid water to exist.
Liquid water is essential for life as we know it, so the habitable zone is a good place to start looking for other planets that could support life. However, other factors would also need to be considered, such as the planet’s size, atmosphere, and the stability of its star. A planet that is too small or too large would not be able to hold onto liquid water, and a planet with an atmosphere that is too thin or too thick would not be able to support life as we know it.
A stable star is also important, as a star that is prone to erupting in sterilizing flares would make it difficult for life to survive.
Why we Looking?
The question of whether life exists beyond Earth has profound implications for our understanding of the universe and our place in it. The answer will change us forever, revealing whether we are alone in the universe or if life is abundant elsewhere. The search for life beyond Earth is also shedding light on our own origins and place in the universe.
The years and decades ahead will bring us ever closer to finding a mirror image of our own planet Earth: a small, rocky world with clouds, oceans, and an atmosphere that could contain signs of life. The gases in this atmosphere, such as oxygen, carbon dioxide, and methane, may not seem significant on their own, but together they could be a strong indicator of life.
Such a world might be hundreds of light-years away, and it may never be within our reach. However, the molecular evidence we can read in its atmosphere, using ever more advanced technology, could give us the answer we have been waiting for since the dawn of humanity: we are not alone.
At the end, I would like to say; life can be unexpectable. Extremophiles, which can survive in hot springs, deep-sea vents, and radioactive zones, show us that life can exist in unexpected places.
This idea suggests that extraterrestrial life may also be extremophiles. We do not know for sure what the meaning of life is, anywhere in the cosmos.
