A little blue marble, lost in the vastness of space, As inconspicuous as a penny dropped in a lake, Yet it provides a home for the human race. Orbiting a star of just the right temperature, If it were dimmer we could not survive the cold, And if it were hotter we would burn up for sure. In a nearly circular orbit; what’s the chance of that? If the gas giants were orbiting near or widely elliptical, Our little rock would be ejected like kicking a cat. We have a thin atmosphere while Venus, the same size, Has crushing pressure and a runaway greenhouse effect, Which makes it uninhabitable; any living thing there dies. We would too if we had not been struck by another planet, Which created the moon and blew away our atmosphere, When it hit the Earth a glancing blow, circled and did ram it. A square blow would have shattered our brittle world, While only the most precise angle could accomplish this. What’s the chance such a thing through space was hurled? If the moon were not there our axis would be unstable, The seasons would vary wildly if our planet tilted over more, It is only by holding steady at 23° that life here is enabled. Had the oceans frozen over, the ice would reflect the light, And never thaw. If they ever boiled away, the clouds Would hold the heat in and never condense. That’s right. Either extreme, freezing or boiling, cannot be reversed. Yet for billions of years we have walked this tightrope, Between 32° to 212° ocean temps and avoided the worst. It takes billions of years for intelligence to slowly evolve, Had this been interrupted by a large meteor or irradiation, Re-starting evolution, then humans would not be here at all. Many improbable events combined to make Earth so nice, The chance of failure was immeasurably close to 100%, The universe isn’t big enough for this to happen twice.