Further to my entry on the ‘Goldilocks Effect’ – the idea that the universe is ‘just right’ for the emergence of human life – I’ve been thinking about one aspect of this richly variegated theme.
At first sight, the earth’s near neighbour, the moon, seems to have no drastic effect on life here on earth. True, it influences ocean tides and offers a bit of light to see things by at night, but, it seems, little more than that.
A closer look at the moon does not seem to be any more promising. For all man’s desire to visit it, it is an entirely dead place – airless, colourless, waterless (or nearly so), lifeless. Its very surface is relic of the early days of the solar system, still bearing the pockmarks of an early onslaught of meteorites. It is a 4-billion-year-old fossil.
And yet the moon seems to be essential to life as we know it. As Hugh Ross says in his Why the universe is the way it is (Baker Books, 2008), the moon is actually quite unusual in a number of ways. Compared with the moons of other planets, its size and mass are especially high in relation to the earth’s. This enables the moon to play a crucial role in stabilising the tilt of the earth’s axis at 23.5 degrees. And this stability protects the earth from catastrophic climate changes.
Then again, the relatively high mass of the moon has meant that it exerts a sufficiently powerful gravitational pull on the earth to slow the earth’s rotation rate to the 24 hours that we experience. If days were much longer than this, then day-night temperature fluctuations would be too great for life to be possible. If days were much shorter than this, rainfall and temperatures would not be so evenly distributed over all the land masses.
And then there are the tides. Life on Earth requires powerful tides in order to cleanse the coastal seawaters and enrich them with nutrients.
Truly, the moon is not just a pretty sight, or an icon of romantic love. Life would not be possible without it.