Somewhere beyond the orbit of Jupiter,
A stone had been traveling for four billion years.
It was not large—by the standards of the greater
Debris that wanders the solar system's fears
Of collision, it was modest: ten kilometers,
A mountain-sized remnant of the early cloud
That had built the planets—the parameters
Of its orbit slowly shifting, the proud
And stable path it had circled for eons
Perturbed by Jupiter's gravity into
A new trajectory—the cons and theeons
Of orbital mechanics finally drew
The stone across the inner solar system's lanes.
It did not aim. It did not think. The stone
Was as thoughtless as the rain that falls on plains
Without intention—the cosmic zone
Of the asteroid belt had released it
Into a path that intersected Earth's
By the mathematics of the orbits—seized it
From its ancient circuit and the berths
Of the outer system, and sent it inward
On a hyperbolic course that took ten
Thousand years to bring it toward
The planet where the dinosaurs, the men
Of the Mesozoic's greatest civilization
(If civilization is what we call
The organized and complex occupation
Of every niche on a planet, the hall
Of a hundred million species living
In the web of the most complex ecosystem
The earth had made, the generous giving
Of the Cretaceous greenhouse)—this system
Knew nothing of the stone.
The stone knew nothing
Of the system.
That is the cruelty—
There was no cruelty in it. The somethings
Of the universe proceed in their duality
Of physics and indifference, and the rock
That would end the Mesozoic world
Was not evil, was not even the shock
Of a vengeful god's hurled
Thunderbolt—it was arithmetic:
Two bodies in the same place at the same time,
The earth and the stone in a geometric trick
Of orbits crossing—the pantomime
Of a collision that no one could see coming
Because no eye on earth looked up to space
With instruments for the incoming humming
Of a mountain falling at twenty kilometers' pace
Per second—twenty times the speed of a bullet,
A hundred times the speed of a jet—
And in the final hours the full of it
Was visible: a brightening star, a threat
That only the mathematics could have warned of,
Crossing the Cretaceous sky in the last
Clear night—and not a single dinosaur mourned of
The future that was vanishing so fast.
Tyrannos hunted in the evening's last light.
Ceratops grazed beside the river's bend.
Hadros called across the coming night.
Pteros' last azhdarchid rode a thermal's end.
Plesios dove beneath the continental shelf.
Mosas hunted in the warm and shallow sea.
And Mammos in his burrow kept himself
Alive through another night—the key
To everything that would come after,
Though he did not know it, could not know,
That the stone was falling toward the rafter
Of the atmosphere, and the final show
Of the Mesozoic was about to begin.
The stone entered the upper atmosphere
At an angle, trailing a column thin
And brilliant of plasma—and from here
The last ten seconds of the Cretaceous
Were written in fire:
The atmosphere compressed
Ahead of the stone, the instantaneous
Heating of the air, the superheated crest
Of the shock wave that preceded impact—
And the stone struck the shallow sea
Of Chicxulub, off the coast, the intact
And ancient limestone shelf—and the free
And terrible energy of ten billion
Hiroshimas released in one second—
One second that ended a hundred million years.
But that is the next chapter's reckoned
And terrible account. Tonight the tears
Are not yet falling, and the stone's appointment
With the earth is still one heartbeat away—
And the Mesozoic's final anointment
Of the evening sky is the last good day
The dinosaurs will see.
Honor the evening.
Honor the last good night before the fire—
The Cretaceous sky in its gentle heaving
Of the stars above the quiet empire
Of the dinosaurs who do not know
That tomorrow the world ends.
For every world
That ends had one last evening's glow
When everything was still and the flag unfurled
Of living was still flying.