famous Canadian Science Fiction novelist
Mark A. Carter reprints an article from
The Atlantic written by
Adrienne LaFrance as the background for his rant about
the Science Fiction disaster
films: Armageddon, Deep
Impact, and Melancholia.
All in all, it does not bode
well for the pale blue dot.
Can you say Extinction Level
Event or ELE.?
An artist's rendering of an asteroid or comet striking Earth.
© Andrea Danti/Shutterstock via The Atlantic. All
Originally published under the
title: The chilling regularity of
The Atlantic - November 07,
One thing we know for sure is
that conditions on Earth were,
shall we say, unpleasant for the dinosaurs at the moment of their
demise. Alternate and overlapping theories suggest the great
beasts were pelted with monster comets,
drowned by mega-tsunamis,
scorched with lava, starved by a landscape stripped of
vegetation, blasted with the radiation of a dying
supernova, cloaked in decades of darkness, and frozen
in an ice age.
Now, a pair of researchers have
new evidence to support a link between
cyclical comet showers and
mass extinctions, including the
Extinction Level Event or
ELE that they believe wiped
out the dinosaurs 66 million
years ago. Michael Rampino,
a geologist at New York University,
and Ken Caldeira, an
atmospheric scientist at the Carnegie
Institution for Science, traced
260 million years of mass
extinctions and found a familiar pattern: Every
26 million years, there were huge impacts and major
die-offs. Their work was accepted by the
Monthly Notices of the Royal Astronomical Society in
In recent decades, researchers
using other methods have found evidence for a 26-million-year
cycle of Extinction Level
Events on Earth, but
the idea has remained controversial and unexplained.
"I believe that our study, using revised dating of extinctions
and craters, and a new method of spectral analysis, is strong
evidence for the cycles," Rampino told me.
Other scientists who have researched
mass extinctions are more
measured about the latest findings.
"I'm sort of agnostic about the larger theory,"
said Paul Renne, Director of Berkeley
Geochronology Center. "But I was really disappointed to
see they used an age-database for the craters which is full of
is the author of another new study that focuses on the
Chicxulub crater, the massive
divot beneath the Yucatán Peninsula
that was created by the same
Extinction Level Event or
ELE blamed for the extinction of the
dinosaurs. Renne and his colleagues believe that the
comet or asteroid that blasted into
Earth and made Chicxulub
also set off a global chain-reaction
of volcanic eruptions
that accelerated the end of the dinosaurs.
Volcanoes were, they believe, erupting continuously for
millions of years. Long enough
to make Hawaii's Kilauea,
which has been flowing since 1983,
seem laughable. "Kilauea
is nothing," Renne told me.
"Kilauea is a flea."
Renne is interested in the possibility that
volcanism is tied to intervals of mass extinction, that
possible connection doesn't explain what kind of cycles might
trigger the awakening of Earth's
most powerful magma systems on a global
scale. That's where theories about
galactic periodicity come back into play.
of the earliest proponents of a periodic record of
Extinction Level Event or
ELE was by a guy named Rich Muller," Renne
said. "He proposed a kind of
phenomenological periodicity in which they didn't really have
a mechanism." In other words,
Muller found the 26-million-year
pattern of mass extinctions
on Earth, but didn't
immediately know what drove the cycle.
The latest findings from
Rampino and Caldeira
build on the idea that regular comet
showers cause intervals of Extinction
Level Events. The showers, the theory goes, are triggered
by the movement of the sun and planets through the
crowded mid-plane of our galaxy. As the sun crosses that
region, it disrupts great clouds of space dust. Those clouds,
in turn, throw off the orbit of comets, sending them careening
In another theory, planetary
scientists suggested that one region of the solar system in particular,
known as the Oort comet cloud,
plays a key role in mass extinctions.
The Oort cloud is
a sprawling region at the border of our solar system that contains
trillions of icy bodies. Muller
put forth a popular hypothesis in the
1980s that said our sun has a sort of
evil twin in the Oort cloud.
This hypothetical star,
he suggested, has an orbital cycle such that it would perturb
its neighboring objects, and send
1 billion of them hurtling toward
Earth every 26 million
years. The star, a binary
to the sun, was nicknamed Nemesis,
and playfully referred to as the
death star. "The binary star, or Nemesis theory, was an
alternate to the Galactic-plane story," Rampino
told me. "But the star was looked
for, but never found, so Nemesis theory is out of favor now."
doesn't 't even believe that any more," Renne told
Rampino and Caldeira
are correct, the next mass extinction
may not be far off in geologic terms, anyway. Our little
corner of the solar system crossed the plane about
2 million years ago, and we are now moving up and through
it. "In the Galactic theory,
we are near the Galactic plane, and we have been in the danger
zone for a couple of million years," Rampino said.
"We are still close to the plane,
maybe 30 light years above the plane, and a light year is 6 trillion
miles. We won't come back across the plane for about another
30 million years."
And while scientists can't be
sure when the next major comet or asteroid impact on
Earth will be, the one that is believed to have killed
the dinosaurs still stands
out as extraordinary, even by ELE
standards. The city-sized
asteroid that created Chicxulub,
for instance, released more energy than
1 billion nuclear bombs when it hit the
hasn't been an impact large enough to cause a major mass extinction
since the impact 66 million years ago," Rampino
said. "That was a 10-kilometer
or six-mile diameter asteroid or comet. The largest impactor
in the last 66 million years was only 5 kilometers or 3 miles
in diameter, which only has one-tenth the energy, so it probably
wouldn't have taken out the dinosaurs. In fact, if a 10-kilometer-sized
object had hit in the last 66 million years, we wouldn't be here.
Our ancestors probably would have been knocked out."
The obvious next question, of
course, is how do we prevent the terrible fate the dinosaurs
suffered? "These events are so
rare in geologic time that the odds of even our great-great-great-great-great-great-grandchildren
witnessing them are really low," Renne said.
"The ultimate proof, which is observation, is not going
to be available to us, unfortunately."
In the meantime, scientists are
actively scouring the skies, and calculating the orbits of
monstrous comets and asteroids. "So far, none are on a collision
course, but the work has just begun in earnest," Rampino
said. "Once we know one
is coming, then there are several options to divert the object.
You don't want to blow it up, that will just increase the numbers
of impactors. One possibility is to have a nuclear explosion
off to one side of the comet or asteroid, pushing it just slightly
off course, or possibly just hitting the object with a rapidly
moving space-craft would provide enough of a nudge."