Knowledge is constantly evolving, and its frontiers advance at ever-increasing rates. Less than 100 years ago, we believed that the Andromeda Galaxy, along with all known "spiral nebulae," were part of the Milky Way. The first planet outside our solar system—or exoplanet—was detected just 25 years ago, and today, more than 3,000 are known! Ironically, we know more about a galaxy over 2 million light-years away than we do about our cosmic neighbors.

Around us, at a distance of "just" 50 light-years, we can find thousands of stars. To reach them, we must travel for 50 years at the speed of light—a staggering 300,000 kilometers per second, which is more than a trillion kilometers per hour. In astronomical terms, if it were possible to travel at this speed, five decades would be like going "right there"—but in human terms, this "right there" is infinitely far from us.

In this neighborhood is the closest star to us, Alpha Centauri. It revealed the existence of an Earth-like exoplanet. Finding a new planet, even one in our Solar System, is no easy task—it requires cutting-edge technology, but also a good dose of persistence and patience. Discovering a new planet involves continuous observations of a star considered a potential host of planets for months on end, sometimes even years. In some cases, tiny changes in the star's brightness are recorded every time a planet passes in front of it. In others, the goal is to measure the "wobble" caused by the gravitational pull that the planets exert on their host star. In both cases, these effects only become evident after a long period of observing the system.

Another careful look at a star with no special appeal in the constellation Aquarius, a mere 40 light-years away, revealed no fewer than seven planets very similar to Earth. Among the new neighbors, three are located in a region conducive to maintaining liquid water, the ideal temperature for sustaining life. The next step will be to verify whether water actually exists.

And if it does exist, what could this mean for human civilization? A lot, because the chances of life existing on these planets are enormous! Life as we know it is based on water. Searching for life beyond Earth means searching for water on other planets. We might finally be able to answer the question that has remained unanswered for millennia: "Are we alone in the universe?"

This certainly doesn't mean we'll move to one of these planets in the coming years, decades, or even centuries. Interstellar travel at speeds close to the speed of light is still the stuff of science fiction. Currently, the furthest place we have a realistic chance of reaching is Mars, which is over 70 million kilometers away. The journey there is much shorter, but it still takes more than six months traveling at 60,000 kilometers per hour.

Mars, however, is "very close" in cosmic terms. Reaching the nearest star will require much more research and development effort from space agencies around the world. If we ever had a real chance of making interstellar travel, we would still face serious ethical dilemmas as a species. Who would we take first? What guarantees would we have of reaching the nearest habitable exoplanet without any accidents along the way—and could we guarantee the travelers' return? Will we be able to keep humanity alive and our planet habitable until we have these questions to address?

Humans have been driving changes in their surroundings for millennia, but never have these changes been so impactful and rapid; we are in the Anthropocene, a new geological epoch. These changes are making our planet an inhospitable environment for humans themselves in a short space of time and irreversibly. At the current rate, even before we conquer Mars, we will be doomed to face severe climate change that will ultimately bring hunger and thirst. An escape trip, whether to Mars or one of the newly discovered planets, is not on the list of possible solutions. Our planet has many similarities, but it remains unique, and the best thing to do is to ensure it doesn't become uninhabitable. As our grandmothers used to say: "Take good care of what you have!"