Here we are with our eyes and our minds and our curiosity, six [now seven] billion passengers aboard a tiny blue boat, bobbing and wheeling our way around one vast Catherine wheel among many.
At the first glance of an alien observer, the Earth may appear to be a small, ordinary rock orbiting an average and unremarkable star.
It has a thin layer of gasses enveloping the planet (our ‘atmosphere’) which is good to have, but isn’t particularly remarkable.
The exact chemical makeup of the planet is certainly unique, but in the same way that any random assortment of letters is unique.
//They might notice atmospheric oxygen, a sign of life…
//What makes the planet interesting is how they’re put together.
But the Earth enjoys a number of unlikely characteristics that sets it apart from other planets.
One of the most fundamental reasons is something that’s quite simple: It’s easy for materials to get mixed together.
Like most planets the Earth is unevenly heated by the Sun, being hotter at its equator and cooler at its poles. But it also spins (creating day and night), and wobbles (creating seasons).
It’s lucky for us that our planet is about half-full of water, which at it turns out is not too much and not too little.
Because of its distance to the Sun and composition of its atmosphere, it has a range of temperatures where water is constantly cycling between states (I.e. between being a gas, liquid, and a solid).
This brings our planet alive.
Water is an excellent solvent, so in its liquid state it carries many interesting dissolved and mixed up materials around and then releases them in other places, acting as a kind of giant ladle that mixes up the soup of Earthly materials.
Carbon, nitrogen, hydrogen, and oxygen, the four central elements to biochemistry, constantly cycle across the Earth in different forms, and often in chemical configurations that make it possibly for life to utilise them.
A relatively short period of time after its formation, the chemical soup of the Earth created by chance a unique type of molecule. It could create rudimentary copies of itself, by attracting component parts and catalysing their reaction to form a similar molecule.
This molecule was the first piece of RNA and the first known instance of life, which went on to built elaborate structures around itself. First it built a cell with structures like walls and organs like the mitochondria, and learned to use sunlight and the energy and materials of other cells.