Timothy Ferriss, Seeing in the Dark
- 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 first glance, the Earth appears to be nothing more than a small, ordinary rock orbiting an average, unremarkable star. But the Earth enjoys a number of unlikely characteristics.
Quite a lot of different types of materials get mixed up quite a lot compared to the other planets in the solar system. With the temperature of the Earth being what it is, and water being so prevalent, it brings our planet alive as it's constantly moving between states (i.e. to gas, to liquid, and back again) and around the planet. It's an excellent solvent, so in its liquid state it carries many interesting dissolved and mixed up materials around the place and then releases them in other places, acting as a kind of giant ladle that mixes up the soup of other materials on the Earth.
Every day, weightless mountains of gas move over our heads. Our atmosphere is the perfect density to retain some heat, but not too much (Venus has too much atmosphere, Earth the perfect amount, Mars too little).
Earth has Jupiter which is acts as a shield for asteroids.
The size of the Earth itself produces enough gravitational pressure to break down the rocks of the crust and cycle them in convection currents, without being too strong to prevent a crust from forming altogether. This creates an ongoing dynamism, cycling the materials of the planet and imbuing them with geothermal energy.
Great oceans, that make up the majority of the surface of the planet, act as a heat sink that moderate any extreme spikes of temperature.
Carbon, nitrogen, hydrogen, and oxygen, the four central elements to biochemistry, constantly cycle across the Earth in different forms, many of which are bioavailable.
An interesting question that I do not know the answer to is; Is there is a cycle for every naturally occurring material on Earth - and I suppose nowadays for man-made ones too? They may differ in time scales by tens of millions of years, but surely all materials from the crust of the Earth upwards into the atmosphere have some kind of cycle?
These attributes have led to the development of life, and thus a biosphere. As life expanded in biomass and worked its way into all the nooks and crannies of the Earth, the biosphere itself became inseparable from these other cycles.
We do not have enough information to know whether or not these things are necessary in the formation of life, as our sample size for planets with life remains at one. These aspects make it all the more difficult to build theories around what is important when it comes to the formation of life.
The Earth has an oversized moon (being the largest moon in the solar system relative to the size of its planet). This has the poetic, if not practical effect, and by sheer cosmic coincidence, the moon appears to be almost the same size as the sun in our sky.
