35 years ago, the Voyager 1 probe looked back more than four billion kilometers away and recorded one of the most iconic images in the history of space exploration. Carl Sagan described that image as “a speck of dust suspended in a ray of sunlight.” It was Earth—home to everyone who had ever lived, loved, and dreamed.

(“Pale Blue Dot”, iconic image taken by Voyager 1 six billion kilometers away, which shows the Earth as a small blue dot above and in the center – Credits: Voyager 1 / NASA )

Seen from space, the Earth appears small, fragile, isolated. And yet, it’s all we have. Earth has no backup. And we know of no place in the Universe where we could restore humanity, in the event of a catastrophic failure with our home planet.

(View of Earth recorded by the Apollo 17 crew traveling towards the Moon NASA/Apollo17)

At this moment when the world’s leaders are preparing to debate the future of the planet at COP 30, in Belém, perhaps it is the ideal time to remember this: our world is rare, and the chance of finding another like it is practically nil.

What makes Earth so special?

It’s just the right distance from the Sun — not too hot, not too cold. It has a protective atmosphere, rich in oxygen, and a magnetic field that defends us from solar radiation. It has abundant liquid water and a Moon that stabilizes its tilt, keeping the seasons and climate predictable.

Everything about it seems to work in harmony, like a cosmic orchestra tuned over billions of years. But it only takes a single instrument to go out of time, a note out of tune, for the concert of life to lose its rhythm.

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But, in recent decades, something has been disturbing this balance. We are polluting the atmosphere, the planet is warming, glaciers are melting, ocean levels are rising — and extreme weather events are becoming increasingly common. And if something goes wrong with Earth, where can we go?

Let’s look around…

Mars? Cold, dry, has no magnetic field to protect against radiation and a rarefied and toxic atmosphere. Venus? A furnace at 480 °C, atmospheric pressure 90 times greater than that on Earth and clouds of sulfuric acid. Living there would be like spending a vacation in a pressure cooker on high heat.

(Human colonization of Mars would depend on closed habitats with a simulated atmosphere, life support systems and resource production, something unfeasible at the moment – ​​Credits: SpaceX)

The moons of Jupiter and Saturn, such as Europa and Titan, are intriguing — they hold underground oceans and organic compounds. They may even harbor some kind of life, but they are extremely hostile to life like ours. Icy worlds, hundreds of millions of kilometers away, under thick layers of ice and exposed to lethal radiation.

Leaving Earth to live in another world today would be like exchanging a cruise in the Caribbean for a tent in Antarctica — or a steaming sauna on the edge of a volcano. We can study these places, perhaps visit, even dream of terraforming them, but none of them are ready to receive us. The only habitable planet we know… is the one we inhabit.

What if we look even further?

Since the 1990s, we have identified thousands of exoplanets — worlds orbiting other stars. Some are in “habitable” zones, where the temperature could allow liquid water. The problem is the enormous distances that separate us from these planets. Distances that are impossible to overcome with our current technology.

(Infographic with 500 exoplanets discovered by 2015 – today there are more than 5000, but none of them are accessible at the moment – ​​Credits: Martin Vargic)

To give you an idea, Voyager 1, which is our fastest spacecraft, needed 36 years just to leave the Solar System, and would need around 80 thousand years to reach Proxima Centauri, the closest star to the Sun.

Even if there is a second Eden lost among the stars, it is far beyond our reach. Our home is this one — and the rest is science fiction. At least for now.

And it’s not because the Earth was made to house humanity. We humans were tailor-made for this Earth we have today.

Our planet was once a world of incandescent lava. Then an ice ball. It has already experienced five mass extinctions, cosmic impacts and eruptions that completely altered the climate. With each change, many species became extinct and the most adapted ones prevailed.

It was the stable and mild climate of the last ten thousand years that allowed a species descended from primates to develop, dominating agriculture, establishing itself in cities and giving rise to our civilization. Humanity flourished in Earth’s geological springtime, a rare interval of planetary balance. A balance that is now threatened, apparently, by the hands of humanity itself.

Earth is rare. And live. It is not just a solitary clod of rock suspended in the darkness — it is a pulsating system, where oceans breathe, forests filter, clouds recycle, and life adapts as a single interconnected network. We are part of it. And what affects one part, affects the whole. Therefore, when we harm our planet, we are harming ourselves. Poisoning the only well from which we drink the water of life.

(Earth, a living planet – AI-generated image (GPT Chat))

Earth is the only place in the Universe we can call home. A welcoming oasis in the midst of the vast desert of the Cosmos. Our planet has no backup and before wanting to terraform Mars or any other world, our best option will continue to be to preserve, here on Earth, the ideal conditions for human life.