• The impact of comets has profoundly influenced the story of life. –Gene Shoemaker

• What are very tiny risks for impacts during a human lifetime become certainties on geological timescales. —
  Clark R. Chapman

• We’re learning all the time that life, in some form or other, is incredibly resilient, albeit fluid
  — episodically morphing into new and better adapted forms rather than succumbing fragilely to the slightest little stress. –Paul Renne, UC Berkeley geologist

• As it turns out, odds
  are about 2.4 times greater that you will be killed by an asteroid or comet than by an air crash or tornado, both taken together.
  Asteroids are surprisingly dangerous. If a big one hit the Earth at the wrong place, it could kill many people. And a sufficiently big one could kill everyone.
  — Killer Asteroids and You, John G. Cramer, January-1992 issue of Analog Science Fiction andFact Magazine

Recompute the Odds

by Malcolm Miller

God does not play dice’, hoped Einstein. But substantial rocks abound, or lumps of ice called comets. If they make a good show as they pass then crowds applaud. Astronomers are the stewards of this race-track, watching for violations, timing the laps. Sometimes there’s a crash – catches most. A wreck that ploughed into the crowd like the Mercedes and left some dead would lead to protests from the public. So what to do? Ask the experts, make them give us the odds, and if they’re less than one in every million, well, who cares! But here’s the rub, those speeding specks are hard to see and now they’re telling us their calculations aren’t exact; they might collide the next time round, or maybe next but three, and they can’t even tell us when or where! Most gamblers like to know the odds, to understand the game and all its rules, whether skill comes into it, and whether one can cheat, but this begins to look like pure chance. Are these astronomer people telling us our lives are balanced on the throw of some God’s random dice?

Deadly Rocks

by Malcolm Miller

Copernicus, Kepler and maybe Newton, too felt that there must be harmony and order in the universe. Each planet in its orbit, majestically tracing out God’s directive, or like the huge and polished flywheel of some monster steel and brass machine moving in exact, unerring circles for ever and a day. Little did they know of past encounters, the late heavy bombardment of left over pieces that marked the face of every solid globe, and later still, the devastation from the sky that fried a billion trilobites, or left huge saurians starving in the dark, with scars still on the Earth that only time and rain and plate tectonics healed. At last we know that tiny planetoids abound, and while they mostly huddle in bounded bands under the pull of larger worlds, a few will always stray and of those some will target Earth, where our own numbers make us vulnerable to deadly rocks and chunks of iron out of space.

Current Plot of Inner Solar System Minor Planets – The Minor Planet Center