Bob Berman - Earth-Shattering: Violent Supernovas, Galactic Explosions, Biological Mayhem, Nuclear Meltdowns, and Other Hazards to Life in Our Universe

W ere all oddly drawn to a theme that started in ancient Egypt and Greece and has perennially appeared in folklore. Its the idea of the phoenix, the creature that emerges from the ashes of a conflagration. The metaphoric implication is that if our world, or at least our culture and all we hold dear, is violently destroyed, something just as vibrant can rise from the ruins.

This has actually happened, not once or twice, but repeatedly. And not just on the local or even planetary level but on epic scales that have rattled the floorless alleyways of the cosmos. Were talking about cataclysms.

In a way, theyre counterintuitive. A quick study of nature shows that all objects display inertiaa strong tendency to keep doing whatever it is they are already doing. Planets whirl around the sun, and nothing is needed to maintain the motion. Meanwhile the sun, the center of all this respectful planetary circling, carries its obedient retinue through the galaxy at 144 miles a second as it participates in the galaxys rotation. The sun and its flock have performed nineteen such circuits since their birth, and, like a mother duck with her ducklings, Sol always returns with the same retinue in tow.

No long-lived observer patiently studying our solar system for millennia would notice anything different with each galaxy rotation. Only if he were armed with a super-telescope and perhaps alerted to be extra-attentive would the onlooker detect a change. Look at that third planet, the blue one, he might whisper. This time around, at some point while its been away on its most recent galactic orbit, most of its life was destroyed. It has undergone a cataclysm. And yet now its surface is crawling with strange new organisms. What magic! What will happen next?

Our ageless observer might be quicker to see that with each galaxy rotation and each return, the sun itself has changed. Each time it completes its 240-million-year circuit of the Milky Ways core, going beyond the stars of Sagittarius, it returns 2.5 percent more luminous. Thats just a little brighter. The change is as subtle as a 75-watt bulb becoming 77 watts, so our onlooker would have to be sharp indeed to notice this alteration. Only after about four circuits of the galaxys core and the passage of a billion years would the brightening of the sun be obvious. Still, even after that protracted interval, the difference would be a mere 10 percent boost. The 75-watt bulb is now 83 watts. But thats enough to make the third planet too hot. In the past single circuit, all its life has vanished.

A close inspection of that planet and its near neighbors shows that Earths large-headed Homo sapiens creatures have built ark-like spacecraft and abandoned their world to colonize the next planet out, the orange one, although life there is proving to be a radiation-filled struggle.

The above scenario is a reasonably accurate look ahead to a time a mere 1.1 billion years from now. The sun will indeed be 10 percent brighter, and all Earth life will indeed be destroyed by the heat, and if we humans still exist, we will surely have fled to the only planet in that anti-sunward direction that has any sort of surface. All others are gaseous and slushy and offer no place to land.