For most of human history, we knew very little about the universe and our place in it. The Earth was a vast and boundless domain, continually revealing new horizons and new discoveries. Knowing nothing about the great extent of outer space, human societies literally regarded the Earth as the center of the universe. In turn, they considered themselves to be the masters of it. After all, they reasoned, the universe must have been created to produce and sustain us. There was no evidence available to the contrary.
The investigation and exploration of our sky gradually revealed to us, however, the presence of a vast universe beyond the Earth. There were points of light which traversed the night sky, appearing at different points at different dates and times. These were recognized to be the planets, and it was reckoned that these must be other worlds, perhaps places similar to our own. The more distant and static points of light in the night sky were known as the stars. Over time, it was calculated that the planets and our Sun didn’t revolve around the Earth, but rather that the Earth and the planets revolved around the Sun. Our belief that we are the center of the universe could no longer be defended.
Observations of the multitudes of stars in the night sky also demonstrated the enormous breadth of the universe. Those stars, it was discovered, are very much like our own. Our star became one of hundreds of billions in our galaxy, a completely insignificant place compared to the true scale and size of our universe. The galaxy, too, was discovered to be just one of billions of other galaxies. As we explored the universe further, we have learned that we are very, very small, indeed. More recently, we have discovered other planets orbiting the stars in our galaxy. This, along with our other discoveries, has revealed to us the truth about our planets position in the universe: it is an entirely ordinary world, orbiting a run-of-the-mill star in an entirely average galaxy.
The exploration of our own solar system, too, has revealed much about us. We have discovered evidence of water on the planet Mars; evidence which leads us to believe that it was likely a world similar to our own at one point, perhaps even able to sustain life. We have learned much about Venus, a world whose parameters are close to ours but whose surface is a hellish, global-warming decimated wasteland. The magnificent outer planets have been found to dwarf our own in size, but we can recognize on them weather patterns and systems very much like those we encounter on Earth. The moons of these outer planets have also provided startling discoveries, such as active volcanoes on Io, an under-the-surface ocean which might sustain life on Europa, and an atmosphere and liquid methane on Titan. By comparing these worlds to our own, we found that our Earth is very unique in its ability to sustain and produce life, but not at all unique in its features, the elements and resources found on it, and the natural processes occurring on it. We have learned that it is much more similar to the rest of our solar system than we before believed.
Finally, we turned our cameras back on Earth. Astronauts looking at Earth from space consistently comment on how thin the atmosphere hangs above its surface, and how no countries or borders are visible on the contiguous stretches of land which warp around our planet. Through the photos of our planet taken from distant spacecraft flying into the darkness of space, too, we can finally recognize the true nature our planet. These photos reveal to us a small speck suspended in space. No countries, not even any continents, are visible. The whole Earth, with every human on it, is a tiny dot dwarfed by the enormous expanse of the cosmos.
What is the importance of these discoveries? What has exploration brought us? Through exploring the cosmos, we have discovered ourselves. Our expanded understanding of the universe has provided us with a fresh perspective about the Human species and the planet Earth we live on. No longer can we consider ourselves special or important in this vast, indifferent universe. By acknowledging that life, and intelligent life, managed to spring up on our regular planet orbiting a regular star tucked away in a normal galaxy, we can perhaps conclude that life is indeed abundant and common across the universe. There is nothing special about Earth or Humanity that would cause us to be the alone. Further, seeing our planet dwarfed by the vastness of space reveals the true fragility of our planet. Our world is not for us to destroy, and destroy it we can easily do. There are many examples of worlds strewn across our solar system and our universe that perhaps one day looked like Earth, but are now dead and desolate worlds. Ours too can become so, and we are especially capable of causing it. We must protect our precious planet.
Perhaps, however, the most important way exploring the universe helps us discover ourselves is how it draws into question the way us Humans approach our problems and interact with each other. Living on a tiny planet in a vast universe, we are very, very small. Without any knowledge of other intelligent civilizations, we are alone. It is upon ourselves and our neighbors that we must rely. Why, then, do we spend so much energy and time killing and destroying each other? Is the conquest of this tiny speck really so important? Faced with the enormous difficulties confronting us and armed with a perspective that realizes how small and alone we are, we should instead be utilizing and pooling the entirety of our resources and cooperating for the benefit of all mankind. Perhaps the astronomer Carl Sagan put this best when discussing the ‘pale blue dot’ picture of Earth taken by Voyager 1 as it left the Solar System:
“The Earth is a very small stage in a vast cosmic arena. Think of the rivers of blood spilled by all those generals and emperors so that in glory and triumph they could become the momentary masters of a fraction of a dot. Think of the endless cruelties visited by the inhabitants of one corner of this pixel on the scarcely distinguishable inhabitants of some other corner. How frequent their misunderstandings, how eager they are to kill one another, how fervent their hatreds. Our posturings, our imagined self-importance, the delusion that we have some privileged position in the universe, are challenged by this point of pale light. Our planet is a lonely speck in the great enveloping cosmic dark. In our obscurity – in all this vastness – there is no hint that help will come from elsewhere to save us from ourselves”