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Throughout the vast majority of the universe, chemistry as we know it hardly ever happens.

Almost the entire universe is dark, cold, and empty space, far from the heat and light of stars. Molecules lie frozen on asteroids or floating in loose gas clouds, too cold or far away from each other to interact.

On the stars that speckle the universe, temperatures are so hot that almost all connections between their molecules are broken down as soon as they form. Inevitably, stars are energetic but are made up of simple stuff.

Surrounding many stars are planets and moons, making up just a tiny fragment of a solar system’s mass. Here in this fraction of a fraction of the universe, temperatures can be right for molecules to combine and create exotic forms of matter. These new molecules are what chemistry is about.

In our own solar system, many of the planets and moons have their own chemistry, from the hydrocarbon oceans of Titan, the largest moon of Saturn, to the closest planet to the sun, Mercury, which is scorched by heat and solar winds.

These planets lie in the balance between between too hot and too cold, and if they have the right amount of pressure, then gasses, liquids or solids interact, bringing together molecules that combine and recombine in a near infinite number of forms.

The Earth is a haven for complex chemistry. On the Earth we sit on a solid surface underneath an ocean of gas that rolls above our heads, on a surface of solid rock, bordered on every side by liquid oceans.

Liquid evaporate and rain and flow across the Earth, carving valleys and canyons which mix tons of sediments, and solvents.

The ebb and flow of the gas in the atmosphere creates weather. Dissolved within it are aromas and scents, which swirl past us every second of the day.

The interaction of these forces move molecules across the surface of the Earth, alternately forming complex molecules and and breaking them back down. The abundance of ‘interfaces’ between solids, liquids, and gas makes the Earth a utopia for complex chemistry.

It’s for this reason that life formed on Earth, and apparently not on other planets of the solar system. After millions of years of these complex interactions, a very unique molecule formed: A molecule that could replicate itself. It is the ancestor of all of Earth’s life.

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Ben McCarthy

Ben McCarthy

Ben is the Founder of Discover Earth and the author of the Big Ideas Network.