Nemesis: Does the Sun Have a 'Companion'?
Nemesis: Does the Sun Have a 'Companion'?
By Robert Roy Britt <mailto:rbritt@...>
Senior Science Writer
posted: 07:00 am ET
03 April 2001
"The trouble with most folks isn't so much their ignorance. It's know'n so
many things that ain't so." -- A favorite quote of Richard A. Muller, by
19th century humorist Josh Billings.
When you think big, as Richard A. Muller does, you're bound to create ideas
now and then that are so compelling you just can't let go of them -- ideas
so outlandish that mainstream scientists are equally eager to dismiss them.
Muller, a physicist at University of California at Berkeley, has had his
share of big ideas
If you don't count the restaurant he owned between 1976 and 1982 ("If anyone
near and dear to you wants to open a restaurant, I can now be hired to talk
them out of it."), Muller's ideas are generally rooted in solid science and
genius extrapolation. He's got a gaggle of prestigious awards to prove it,
with titles that say things like "outstanding" and "highly original."
But Muller's biggest idea is a real Nemesis. Or so he claims.
Like a thorn in the side of mainstream researchers, Muller's Nemesis theory
-- that our Sun
has a companion star responsible for recurring episodes of wholesale death
and destruction here on Earth -- seems to reemerge periodically like
microbes after a mass extinction.
It's a theory that has many detractors. And it's a theory that has been
beaten down and left for dead in the minds of most scientists.
Yet it is a theory that just won't die.
Nemesis is cautiously supported by a handful of scientists, who often sound
like ringside rooters eager for a victory but thankful they don't have to
put the gloves on. Muller meanwhile acknowledges the possibility that the
whole idea could turn out to be wrong, but he is nonetheless confident that
Nemesis will be found within 10 years.
"Give me a million dollars and I'll find it," Muller said in a recent
Brave words for a bold theory that if proven true would shake up everything
we know about the formation and evolution of our solar system.
Genesis of Nemesis
Muller's idea for Nemesis came to him 1983. Luis Alvarez, then an emeritus
professor of physics at the University of California at Berkeley, and his
son Walter had recently put forth the theory that a giant impact
> had wiped out the dinosaurs. (This idea, like so many others that are nowwidely accepted, met with staunch criticism when it was introduced because
it, too, was not mainstream).
Around the same time, two other researchers had suggested yet another
controversial idea, that mass extinctions occurred at regular intervals --
every 26 million years or so. Scientists immediately folded the ideas into a
new and breathtaking possibility: Impacts by space rocks were causing
massive global species destruction every 26 million years.
Luis Alvarez was Richard Muller's mentor, and he suggested that Muller try
to debunk the periodicity argument. Pondering this, Muller dreamed up the
fanciful companion to the Sun as a possible cause, and with Berkeley's Piet
Hut and Marc Davis of Princeton, worked out the details.
Muller gave the object the name of the Greek goddess of retribution --
fitting for a killer star that roamed stealthily beyond the solar system
flicking comets at dinosaurs.
In the end, the idea looked surprisingly plausible to Muller and his
colleagues, and the results of their work were ultimately published in the
journal Nature in 1984. Muller then wrote a book about Nemesis, and he has
pursued the companion star, while also doing other research, ever since.
Tossing comets at us
Nemesis, as Muller sees it, is a common red dwarf star
<http://www.space.com/reference/brit/stars/structure_2.html> that would be
visible through binoculars or a small telescope, if only we knew which of
some 3,000 stars to look at. These are stars that have been cataloged, but
their distances are not known.
Any one of them could be the Death Star, as Nemesis has come to be called by
Red dwarfs are the most common stars in the galaxy. They are small and
relatively cool, dimmer than our Sun. The notion of companion stars is also
exceedingly common -- more than half of all stars are part of such a binary
system, in which two stars are thought to form out of a single cloud of gas
Binary stars settle into a gravitational dance around a common point in
space. The smaller of the two stars does most of the orbiting, whereas the
larger one is much closer to the center of the dance routine. It's like two
kids on a seesaw. For the thing to work properly, the heavier child must sit
closer to the center of the apparatus.
Muller figures Nemesis' orbit ranges from 1 to 3 light-years away from the
On its closest approach, the lethal companion would pass through a vast, but
sparsely populated halo of primitive comets called the Oort Cloud
tml>, which surrounds our solar system from beyond Neptune's orbit out to
nearly a light-year away. (The Sun's nearest known star, Proxima Centauri,
is about 4.25 light-years away).
During this passage through or near the Oort Cloud, the gravity of Nemesis
would scatter a furious storm of primordial comets that had been relatively
undisturbed for 4.5 billion years, since the solar system came into being.
Dislodged from their once-stable orbits, millions or billions of these
comets would travel to the inner solar system over millions of years, pulled
toward the Sun by its gravity. A handful would run into Earth along the way,
and the flurry of would result in mass extinctions.
Simple enough. But Nemesis has for years been dogged by a misunderstanding,
Muller says. Most researchers think the theory was long ago dismissed by
competing data that claimed its orbit was not possible.
The orbit assumed for Nemesis is an unusual one, Muller admits. No star has
ever been found to orbit so far from a companion. "And that really bothers
people," he said. "It makes them think that this is a really far-out idea,
But computer models developed by Muller and his colleagues predict that such
an orbit must occur at some point in the evolution of most binary star
systems. "We just haven't found such systems yet," he said.
And while Muller appreciates the natural and healthy skepticism of other
scientists, he figures they are not interested in funding a search because
they erroneously assume that Nemesis cannot be found.
Jonathan Tate is the director of Spaceguard U.K
<http://www.space.com/news/asteroid_british_000915.html>., which lobbies for
a government response to the threat of asteroids. Tate is among those who
see no rush to find Nemesis. He would rather see money spent on more
immediate searches for asteroids closer to Earth that might prove to be
humanity's undoing in coming decades or centuries.
As Tate points out, proving that mass extinctions occur every 26 million
years, regardless of the cause, is only of academic interest: Humans may not
likely to be around to care, as many researchers don't expect our species to
last that long. If we do survive, there will likely be plenty of time to
Meanwhile, many scientists see little or no credibility to the studies
alleging periodicity in mass extinctions
.html>, and hence no need for a Nemesis theory.
Numerous studies have reported cycles in either impacts or mass extinctions.
The period between peaks in these studies mostly range from 26 million to 35
million years. Andrew Glikson of the Australian National University says
that trying to pin down things that happened so long ago is no simple
challenge. For one thing, space rocks that land in the ocean leave few
clues, Glikson points out, and Earth is roughly two-thirds water.
l> has always had a crust that is on the move. Evidence gets buried,
destroyed, and folded into oblivion by the same process that creates
mountains and moves continents.
"Some of the suggested periodicities are more likely to represent
statistical artifacts than robust observations," Glikson said.
David Raup, a University of Chicago paleontologist, made the original
mass-extinction periodicity argument two decades ago along with colleague J.
John Sepkoski. The pair studied marine fossil records over a 250
million-year period that they say showed significant spikes every 26 million
"To me, the periodicity idea is as well supported as many ideas that have
been adopted into the conventional wisdom, but the scientific community is
heartily skeptical," Raup told SPACE.com. "Of the 15 or so re-analyses of
our data published since the original paper, about half support periodicity
and half reject it. It's is still very much in the eye of the beholder."
Muller supports the statistics more emphatically.
"There is a peculiar pattern in mass extinctions, something that cannot be
dismissed as a statistical fluctuation," Muller said. "It requires some
Raup, now retired from active research, would not venture a guess as to when
or whether Nemesis might be found, but he expressed hope in the idea: "I am
glad Rich [Muller] is still working on it because it may take a lot of
The galactic plane, Planet X and black holes
Other ideas have been put forth to explain the alleged periodicity in mass
The most widely accepted is the suggestion that the solar system, as it
revolves around the center of the Milky Way, bobs up and down through the
plane of the galaxy. This plane is full of gas and dust that never became
stars, which collectively has a certain amount of gravity that some expect
might dislodge comets from the Oort Cloud.
There are doubts, however, about the amount of mass in the galactic plane
and whether or not the timing coincides with the periodicity of mass
Others have suggested a dim failed star known as a brown dwarf might be
lurking in the distant fringes of the solar system. Muller called the
increasing rate of discovery of brown dwarfs, including one that is just 13
"extremely discouraging." For if Nemesis were a brown dwarf, it would be
harder to find.
Yet another enduring idea is that another large planet lurks beyond Pluto.
This so-called Planet X would be a gas ball up to five times the size of
Earth, according to some predictions. Even the possibility of a black hole
has been raised. Few researchers support these two ideas.
Evidence from the Moon
The best evidence for periodic impacts on Earth may ultimately come from the
Moon. While the Earth's crust has been stretched, squashed and folded
violently its whole life, the Moon is relatively static, preserving a far
more accessible geologic record.
A year ago Muller, Berkeley geologist Paul Renne and then-graduate student
Timothy Culler found the Moon underwent a flurry of impacts
between 400 million and 600 million years ago. The active period (which may
still be going on) presumably affected Earth as well since both bodies are
in roughly the same spot in the solar system.
Muller says the sudden increase offers indirect evidence for a sudden change
in the orbit of Nemesis, which might have been caused by a passing star.
But the study did not turn up evidence for the 26 million-year periodicity,
as hoped. Muller says there was not enough data. The study involved 155
microscopic glass beads formed in the intense heat of lunar impacts and
later brought to Earth, in a single gram of soil, by the Apollo 14 crew.
But given that there are "several hundred pounds (kilograms) of [lunar] dust
and rocks that have not been analyzed," Muller plans another more detailed
Whether or not he finds evidence for Nemesis in Moon dust, it's clear that
Muller won't stop looking. He is a man of enduring confidence. But he is
also a remarkably conservative scientist, quick as anyone to point out that
there is no proof until there is proof.
"I'm realistic," he said. "I may be wrong."
And he recognizes that if the Death Star is not found, the whole idea could
become a real Nemesis for the big thinker who dreamed it up.
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