Venus, from six miles high, shines brighter than the landing lights of a passing jet. The milky-way, and occasionally the northern lights look resplendent against a deep night sky. Astronomers say Venus shines brightly because dense clouds in its atmosphere reflect the sunlight. They also describe an environment completely inhospitable due to a surface temperature of 800 degrees C—about the temperature near the turbines of your jet engines.
Mars shines too, appearing slightly orange, and very bright. We have little robots crawling around on its surface right now. They report a temperature cold enough to make dry ice at the planet’s poles.
Although dazzling and beautiful, there is nothing visible out there that looks remotely livable…
It’s minus 56 degrees outside. Fahrenheit or Celsius makes no difference, because at that temperature, they are the same—as cold as air gets. Just like the speed of sound is as fast as air can move, -56 degrees is pretty much as cold as it will go. That’s the temperature in the arctic, and world-wide, over 30,000 feet.
On the other side of the windshield, the air is cold enough to kill. The Plexiglas window has embedded heating elements which keep it from frosting over. The temperature inside our airplane is a perfect 23 degrees C, and outside, a frigid lifeless world. Free-fall from 33,000 ft at terminal velocity, and it’s a little over 3 minutes to the ground. Could die of oxygen deprivation and frostbite before hitting the ground.
Aside from the cold, atmospheric pressure outside is less than the gas pressures in our circulatory systems—with each breath, we’d be exhaling oxygen, and unconscious in less than a minute—dead a couple of minutes after that. The plane maintains an 8 psi pressure differential between the passenger cabin and the world outside.
Then there’s the wind. Unfettered by the frictional effects of the Earth surface, the wind howls at incredible speeds. 65 mph is enough wind velocity to make walking impossible; hurricanes destroy buildings, power-lines and trees with winds blowing over 100 mph. Tornadoes cause utter destruction with winds near 200; skin flails from the bones above 400 mph; and here we sit in a comfortable, pressurized haven traveling 530 mph, against jet-steam winds a little over 200. If these conditions existed at the surface, nothing would survive.
This is not rare, but rather the usual state of things. The atmosphere covers the whole earth. Look up from anywhere, and we survive just a few miles below an unlivable, frozen, howling hell.
I consider this, flying from place to place. As we descend, the temperature begins to warm, following a general rule of about 2 degrees centigrade per thousand feet. By the time we land, this time in Great Falls, Montana, the temperature is a cool 10 C, warm enough for a light jacket.
The wind, a 220 mph raging river overhead, has slowed to a whispering 4, barely challenging the efforts of a butterfly. Air pressure increases steadily, as measured by the altimeters, about 1 inch mercury/thousand feet. By ten thousand feet, we could breathe comfortably for any length of time, if the pressurization system failed.
Gradually, steadily, the world becomes closer, warmer, and more gentle, welcoming our travelers back from a sterile sky. What remarkable conditions we live in! In all the world, it is here, where we live, that is livable. For millions of miles in any direction, there is nothing but extremes of cold, or heat, or anything but gentle spring days. We live in a comfortable haven, hurtling through a hostile universe—not much different than an airplane in flight, when you think about it.
Could it be chance? Simple good fortune, that conditions here sustain us so well? Maybe life emerges wherever conditions are right?
About the same chance that an airplane flying through the stratosphere, providing comfortable travel to its passengers, happened by luck and lightning, as this earth and its life came of accidental means.