SAND

Roald Dahl once observed that life is a series of thousands of tiny miracles, and this quote was accompanied by a photograph of somebody with a handful of sand.

I’m sure that you have held a handful of sand and allowed it to fall through your fingers. Did you notice how every grain of sand falls downwards in the same direction, following the contours of space itself, curved by the mass of the Earth? The path of each grain of sand only shifted slightly by the movement of the wind, the movement of the air molecules in the atmosphere of the Earth, which also remains trapped around the Earth by the same curved space that draws down the grains of sand.

The Earth is 150,000,000 km from the sun, and the sun itself is an enormous thermonuclear bomb, engaged in a continuous explosion, which emits a fierce storm of high energy ionised particles out into the solar system. This wind of particles has stripped Mars and Mercury of their atmospheres. So how does the Earth retain its atmosphere? Luckily the Earth is bigger than Mars, and even though it is 40% closer to the sun, it has a liquid iron core, and the rotation of the Earth and its iron core generates a magnetic field, and it is this magnetic field that forms a protective layer around the Earth, repelling the ionised solar wind which would otherwise have stripped the atmosphere away from the Earth and made it devoid of life.

The Earth retains its oceans for the same reason. Water, brought to this earth by thousands of comets during a period called the Late Heavy Bombardment about 4 billion years ago. In the oceans, over many years, sedimentary layers formed on the ocean floor, and sometimes the movement of the liquid layers of magma under the crust of the Earth forced this sedimentary rock up out of the ocean, and then the wind and the rain eventually eroded it down to form grains of sand. On tropical islands, the very white sand that you see is the result of the excretions of parrot fish after they have chewed on coral, so this is another unusual source of the sand which shapes every beach on the planet.

So when you pick up a handful of sand you can think about the oceans and the sediment and the wind and rain and the parrot fish that have created the sand that you hold, and when you let it fall through your fingers you can see how it follows the contours of space itself, and you might notice it blown around by the wind, the movement of the atmosphere, protected by the Earth’s magnetic field, and you might think of these miracles, tiny and vast.