From Earth to the Edge of the Universe: The True Scale of the Cosmos

Imagine discovering that there is a part of the universe that will never be visible to us any human being No matter how advanced technology becomes, or how many billions of years humanity survives, how powerful the telescopes of the future will be. There are regions of the cosmos whose light will never reach us. They exist, but will forever remain beyond our reach. This is one of the most intriguing conclusions of modern cosmology, and the most impressive part is It is that, to understand this mystery, we must begin exactly where we are now. Right now, as you watch this video, you are traveling through space. at an astonishing speed without even realizing it. The Earth rotates around its own axis at approximately 1,670 kilometers per hour at the Equator. At the same time, it orbits the Sun at approximately 107,000 kilometers per hour. Our Solar System is also traveling around the center of the Milky Way, at a distance of about at 828,000 kilometers per hour, and yet everything still appears completely motionless. This is merely the first demonstration of how our perception can deceive us when We strive to understand the true scale of the universe. The planet we live on seems gigantic. oceans, mountains, deserts, and continents give the impression that the Earth is practically infinite for those who live upon its surface. Even dedicating an entire lifetime to exploring it, it would be impossible to know every existing place. But it takes only a few steps back along the scale of the cosmos to realize that our planet occupies an almost invisible position. The first destination of this journey is a place that is extremely familiar—the Moon. Every night she appears in the sky, so close to our eyes that it seems possible Reach her easily. However, this sensation is merely an illusion created by perspective. The average distance between the Earth and the Moon is approximately 384,400 km. To better visualize this vastness, imagine lining up about 30 planets, Earth side by side. This would be, approximately, the distance separating the two celestial bodies. That is precisely why the Apollo missions required approximately 3 days reach the lunar surface. Even using some of the most powerful rockets ever built by humanity, Crossing this space has never been a simple task. Now imagine making the same journey using the fastest race car in the world, maintaining your maximum speed without stopping for a single second. Still, it would take more than 40 days to reach the Moon. It is at this moment that we begin to realize how difficult it is for our brain understand astronomical distances If the Moon is already so far away, Mars completely transforms this perception. The so-called Red Planet is, on average, about 225 million km away from Earth. although this distance varies depending on the positions of the planets in their orbits around the Sun. At times, they become relatively close. In others, separated by hundreds of millions of kilometers. When we finally send astronauts to Mars, they will be so far away that they will look back for the sky and summer, the Earth is just a small glowing dot lost in the darkness. A photograph captured by the Curiosity rover in 2014 recorded exactly this perspective. A tiny blue glow almost invisible among billions of stars. Yet there is an even more surprising detail. If an astronaut were walking across the surface of Mars and decided to turn on For your family on Earth, this conversation would never take place in real time. Since no information can travel faster than the speed of light, each message It would take approximately 3 to 21 minutes to reach the destination, depending on the position. of those two planets at that moment. Unlike a regular call, each question would be followed by a long silence before of the answer. For the first time in human history, conversing would mean waiting several minutes. between each sentence. Even so, Mars remains merely our cosmic backyard. Far beyond the orbit of known planets, there exists a small object crafted by hands humans who have continued their silent journey through space for nearly half a century. Launched in 1977, the Voyager spacecraft had the initial mission of exploring Jupiter and Saturn. No one could have imagined that she would end up starring in one of the greatest adventures in history. space exploration After fulfilling its primary objectives, the Voyager continued traveling ever farther away, becoming the man-made object to have reached the greatest distance from the Earth Today, she traverses the interstellar space, a region where the direct influence of the wind The sun virtually disappears. Even being tens of billions of kilometers away, it continues transmitting scientific data. precious to our planet. Yet perhaps its most fascinating aspect is not scientific. Next to the spacecraft, there is a golden disc known as the Golden Record. Nele, scientists gathered sounds from nature, music from different cultures, and images from Earth, representations of human anatomy, scientific records, and greetings in dozens of languages. It is an interstellar time capsule, created to present who we are in case any civilization Intelligent, I found this little messenger lost in the vastness of the cosmos. While you were finishing listening to this part of the story, Voyager 1 traveled several extra kilometers toward the unknown. And the most impressive thing is that, despite nearly 50 years of continuous travel, she It hasn't even fully left the most distant region of our solar system yet. It's hard to believe, but Voyager 1 is still far from completely leaving the domains do Sol. Far beyond the giant planets lies a vast frontier, practically invisible. the Oort cloud This immense sphere of frozen bodies surrounds the solar system and may extend for nearly a light-year in all directions. It is considered the nursery of numerous comets that occasionally visit the region. inside our system At current speeds, Voyager will take approximately 300 years just to reach This more distant region, and this is just the beginning. It will take approximately 30,000 years to cross it completely. To put this number in perspective, around 30,000 years ago, the last The Neanderthals disappeared from Earth. Whole civilizations were born, flourished, and vanished within that span of time. While the small probe continues its silent journey toward the unknown. It is at this point that we realize the units used so far no longer make sense. Kilometers and even astronomical units become too small to describe distances so absurd. From here on, astronomers begin using a new unit of measurement, the light-year, which represents The distance traveled by light in a single year, approximately 9.46 trillion kilometers. Even traveling at the incredible speed of light, it would still take more than one year to cross only this outer region of the Solar System. Beyond the Sun, we find our nearest stellar neighbor. It's hard to believe, but Voyager 1 is still far from completely leaving the domains do Sol. Far beyond the giant planets lies a vast boundary, practically invisible. the Oort cloud This immense sphere of frozen bodies surrounds the Solar System and may extend for nearly a light-year in all directions. It is considered the nursery of numerous comets that occasionally visit the region. inside our system At current speeds, Voyager will take approximately 300 years just to reach This more distant region, and this is just the beginning. It will take approximately 30,000 years to cross it completely. To put this number in perspective, around 30,000 years ago, the last Neanderthals disappeared from Earth. Entire civilizations were born, flourished, and vanished within that span of time. While the small probe continues its silent journey toward the unknown. It is at this point that we realize the units used so far no longer make sense. Kilometers and even astronomical units become too small to describe distances so absurd. From here on, astronomers begin using a new unit of measurement, the light-year, which represents The distance traveled by light in a single year, approximately 9.46 trillion kilometers. Even traveling at the incredible speed of light, it would still take more than one year to cross only this outer region of the Solar System. Beyond the Sun, we find our nearest stellar neighbor. Proxima Centauri is located approximately 4.24 light-years from Earth. It seems a small number, but just imagine the following. If Voyager 1 were pointed directly at you, it would take approximately 75,000 years to reach that star. The entire history of human civilization recorded in books occupies only a small fraction from this time onward Now imagine making this journey driving a car at maximum speed, without stopping. just one second. The journey would take about 12 million years. Our ancestors had not yet belonged to the genus Homo when this journey would have begun. These numbers completely defy our intuition. But there is an even more curious consequence of these distances. Since the beginning of the 20th century, the Earth has been emitting radio waves, transmissions of television and communication signals traveling through space at the speed of light. This means that at this moment, there exists a gigantic bubble of human signals spreading out expanding in all directions throughout the universe. If there existed a technologically advanced civilization located about 100 years light of distance, equipped with extremely sensitive instruments, she could be now capturing radio transmissions sent by humanity a century ago. Perhaps they were listening to old radio stations, military messages, or even the first programs. of television in our story. However, beyond that limit, our signals simply haven't had enough time yet. to arrive When we broaden this perspective, we perceive something surprising. This entire vast sphere of human transmissions, built up over more than 100 years, occupies only a nearly imperceptible fraction of the Milky Way. Our galaxy is approximately 100,000 light-years in diameter. That radio bubble, which seems gigantic to us, represents only a tiny a lost point within her It's like lighting a small match in the middle of an entire continent and expecting its light to be seen. Light illuminate everything around. The Milky Way, in turn, is far more extraordinary than we imagine when we look at it toward the sky at night. It contains between 200 and 400 billion stars. Many of them have their own planetary systems. The most recent surveys indicate that the majority of stars likely possess at least one planet in orbit. This means our galaxy may contain hundreds of billions of worlds, some completely different from Earth and others potentially similar to ours. At the center of this gigantic structure lies an invisible giant, Sagittarius. Abra, a supermassive black hole with a mass of about four million times that of the Sun. Although we cannot see it directly, its gravity keeps entire stars in orbit. around him at astonishing speeds. And even this immense galaxy, which for thousands of years we believed represented practically The entire universe revealed itself to be just one among countless others. Until the early 20th century, many astronomers believed that all nebulae observed in the sky belonged to the Milky Way itself. It was only after revolutionary observations that it became clear that some of these spots luminous ones were, in fact, completely independent galaxies located millions of light-years away. Suddenly, the universe became vastly larger than anyone had ever imagined. And this discovery was just the beginning.