Earth's Moon is Rare Oddball

Earth's Moon is Rare Oddball

The moon formed after a nasty planetary collision with young Earth, yet it looks odd next to its watery orbital neighbor. Turns out it really is odd: Only about one in every 10 to 20 solar systems may harbor a similar moon.

New observations made by NASA's Spitzer Space Telescope of stellar dust clouds suggest that moons like Earth's are—at most—in only 5 to 10 percent of planetary systems.

"When a moon forms from a violent collision, dust should be blasted everywhere," said Nadya Gorlova, an astronomer at the University of Florida in Gainesville who analyzed the telescope data in a new study. "If there were lots of moons forming, we would have seen dust around lots of stars. But we didn't."

Gorlova and her team detail their findings in today's issue of the Astrophysical Journal.

Violent birth

Shortly after the sun formed about 4.5 billion years ago, scientists think a vagrant planet as big as Mars smacked into infant Earth and ripped off a chunk of our home's smoldering mantle. The rocky, dusty leftovers fell into orbit around our wounded planet, eventually coalescing into the moon we see today.

The scenario is unique among other moons in the solar system, which formed side-by-side with their planet or were captured by its gravity. Gorlova and her colleagues looked for the dusty signs of similar smash-ups around 400 stars, all about 30 million years old—roughly the age of our sun when Earth's moon formed.

Only one of all the stars they studied, however, displayed the telltale dust. Considering the frequency of planetary solar systems, the amount of time the dust should stick around and the window for moon-forming collisions to occur, the scientists were able to peg the frequency of extrasolar bodies that formed like our moon.

The estimate, however, is possibly a generous one.

"We don't know that the collision we witnessed around the one star is definitely going to produce a moon," said study co-author George Rieke, an astronomer at the University of Arizona in Tucson, "so moon-forming events could be much less frequent than our calculation suggests."

Odd moon out?

Planetary scientists like Gorlova and Rieke think infant solar systems can form moons between 10 and 50 million years after a star forms. That only a single star with collision-generated dust could be found in their latest research, the astronomers said, indicates that the 30 million-year-old stars in the study have finished making their planets.

"Astronomers have observed young stars with dust swirling around them for more than 20 years now," said Gorlova, noting that the dust could be collision-derived or primitive planet-forming material. "The star we have found is older, at the same age our sun was when it had finished making planets and the Earth-moon system had just formed in a collision."

While most the our type of moon may be rare, astronomers think there are billions of rocky planets out there with plenty of moons orbiting around them. The upshot for lunar lovers? There could be millions—or billions—of Earth-like moons drifting through the cosmos.

An Unauthorized Autobiography of Science

An Unauthorized Autobiography of Science

Journal article explanations of how science works often differ from the actual proces

According to 55 percent of 350,000 people from 70 countries who participated online in Richard Wiseman’s Laugh Lab experiment (discussed in last month’s column), this is the world’s funniest joke:

Two hunters are out in the woods when one of them collapses. He doesn’t seem to be breathing, and his eyes are glazed. The other guy whips out his phone and calls the emergency services. He gasps, “My friend is dead! What can I do?” The operator says, “Calm down. I can help. First, let’s make sure he’s dead.” There is a silence, then a shot is heard. Back on the phone, the guy says, “Okay, now what?”

So say the data, but according to Wiseman’s personal narrative describing how the research was actually conducted (in his new book Quirkology), he believes that “we uncovered the world’s blandest joke—the gag that makes everyone smile but very few laugh out loud. But as with so many quests, the journey was far more important than the destination. Along the way we looked at what makes us laugh, how laughter can make you live longer, how humor should unite different nations, and we discovered the world’s funniest comedy animal.” Chickens notwithstanding, such first-person accounts in popular science books that include the journey and not just the destination afford readers a glimpse into how science is really carried out.

Formal science writing—what I call the “narrative of explanation”—presents a neat and tidy step-by-step process of Introduction-Methods-Results-Discussion, grounded in a nonexistent  “scientific method” of Observation-Hypothesis-Prediction-Experiment followed in a linear fashion. This type of science writing is like autobiography, and as the comedian Stephen Wright said, “I’m writing an unauthorized autobiography.” Any other kind is fiction. Formal science writing is like Whiggish history—the conclusion draws the explanation toward it, forcing facts and events to fall neatly into a causal chain where the final outcome is an inevitable result of a logical and inevitable sequence.

Informal science writing—what I call the “narrative of practice”—presents the actual course of science as it is interwoven with periodic insights and subjective intuitions, random guesses and fortuitous findings. Science, like life, is messy and haphazard, full of quirky contingencies, unexpected bifurcations, serendipitous discoveries, unanticipated encounters and unpredictable outcomes. This chaotic process helps to explain, in part, the phenomenal success in recent decades of first-person popular accounts by scientists of how they actually did their research. The effect is especially noteworthy in works exploring the peculiarities of life.

Steven Levitt and Stephen Dubner’s Freakonomics (William Morrow, 2006) illuminates the power of incentives through certain oddities. For instance, that most drug dealers live with their mothers because only the top guys make the big bucks while the rest bide their time and pay their dues, or that baby names tell us about the motives of parents. Cornell University professor Robert Frank’s The Economic Naturalist: In Search of Explanations for Everyday Enigmas (Basic, 2007) employs the principle of cost-benefit analysis to explain such idiosyncrasies as why drive-up ATM keypads have Braille dots (because it is cheaper to make the same machine for both drive-up and walk-up locations), why brown eggs are more expensive than white eggs (because there is less demand and the hens that lay them are larger and consume more food), why it is harder to find a taxi in the rain (because more people use them when it is raining, most cabbies reach their fare goals earlier in the day), and why milk is stored in rectangular cartons but soft drinks come in round cans (because it is handier to drink soda directly from a round can but easier to pour and store milk in a rectangular carton).

In my October column I railed against the artificial (and odious) ranking of technical science writing over popular science writing. I suggested that the latter should be elevated to a more exalted standing of “integrative science,” where good science writing integrates data, theory and narrative into a useful and compelling work. And here I would add that exploring the minutiae of life, especially on the quirky borderlands of science, makes the scientific process more accessible to everyone. Where a narrative of explanation might read something like “the data lead me to conclude...,” a narrative of practice reads more like “Huh, that’s weird...”

Greatest Mysteries: How Did Life Arise on Earth?

Greatest Mysteries: How Did Life Arise on Earth?

Earth is estimated to be about 4.5 billion years old, and for much of that history it has been home to life in one weird form or another.

Indeed, some scientists think life appeared the moment our planet's environment was stable enough to support it.

The earliest evidence for life on Earth comes from fossilized mats of cyanobacteria called stromatolites in Australia that are about 3.4 billion years old. Ancient as their origins are, these bacteria (which are still around today) are already biologically complex—they have cell walls protecting their protein-producing DNA, so scientists think life must have begun much earlier, perhaps as early as 3.8 billion years ago.

But despite knowing approximately when life first appeared on Earth, scientists are still far from answering how it appeared.

"Many theories of the origin of life have been proposed, but since it's hard to prove or disprove them, no fully accepted theory exists," said Diana Northup, a cave biologist at the University of New Mexico.

The answer to this question would not only fill one of the largest gaps in scientists' understanding of nature, but also would have important implications for the likelihood of finding life elsewhere in the universe.

Lots of ideas

Today, there are several competing theories for how life arose on Earth. Some question whether life began on Earth at all, asserting instead that it came from a distant world or the heart of a fallen comet or asteroid. Some even say life might have arisen here more than once.

"There may have been several origins," said David Deamer, a biochemist at the University of California, Santa Cruz. "We usually make 'origins' plural just to indicate that we don't necessarily claim there was just a single origin, but just an origin that didn't happen to get blasted by giant [asteroid] impacts."

Most scientists agree that life went through a period when RNA was the head-honcho molecule, guiding life through its nascent stages. According to this "RNA World" hypothesis, RNA was the crux molecule for primitive life and only took a backseat when DNA and proteins—which perform their jobs much more efficiently than RNA—developed.

"A lot of the most clever and most talented people in my field have accepted that the RNA World was not just possible, but probable," Deamer said.

RNA is very similar to DNA, and today carries out numerous important functions in each of our cells, including acting as a transitional-molecule between DNA and protein synthesis, and functioning as an on-and-off switch for some genes.

But the RNA World hypothesis doesn't explain how RNA itself first arose. Like DNA, RNA is a complex molecule made of repeating units of thousands of smaller molecules called nucleotides that link together in very specific, patterned ways. While there are scientists who think RNA could have arisen spontaneously on early Earth, others say the odds of such a thing happening are astronomical.

"The appearance of such a molecule, given the way chemistry functions, is incredibly improbable. It would be a once-in-a-universe long shot," said Robert Shapiro, a chemist at New York University. "To adopt this [view], you have to believe we were incredibly lucky."

The anthropic principle

But "astronomical" is a relative term. In his book, The God Delusion, biologist Richard Dawkins entertains another possibility, inspired by work in astronomy and physics.

Suppose, Dawkins says, the universe contains a billion billion planets (a conservative estimate, he says), then the chances that life will arise on one of them is not really so remarkable.

Furthermore, if, as some physicists say, our universe is just one of many, and each universe contained a billion billion planets, then it's nearly a certainty that life will arise on at least one of them.

As Dawkins writes, "There may be universes whose skies have no stars: but they also have no inhabitants to notice the lack."

Shapiro doesn't think it's necessary to invoke multiple universes or life-laden comets crashing into ancient Earth. Instead, he thinks life started with molecules that were smaller and less complex than RNA, which performed simple chemical reactions that eventually led to a self-sustaining system involving the formation of more complex molecules.

"If you fall back to a simpler theory, the odds aren't astronomical anymore," Shapiro told LiveScience.

Trying to recreate an event that happened billions of years ago is a daunting task, but many scientists believe that, like the emergence of life itself, it is still possible.

"The solution of a mystery of this magnitude is totally unpredictable," said Freeman Dyson, a professor emeritus of physics at Princeton University in New Jersey. "It might happen next week or it might take a thousand years." 

Once considered to be only cellular couriers, scientists now know RNA performs a host of important functions. This artist rendering shows "small RNAs" able to regulate cellular development, pathogen defense and stress response. 

Nuclear Scientists Explore the Core of Existence

Nuclear Scientists Explore the Core of Existence

The strong nuclear force is the strongest of the four fundamental forces of nature, binding protons and neutrons in the cores of atoms. Yet the same force prevents those fundamental particles from combining in certain combinations.

When I first learned that, my entire view of the physical world was shaken. It was like learning that only certain mixes of peanut butter and jelly could be put into a sandwich.

As a journalist at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University, one of the nation’s top nuclear science laboratories, the strangeness of this truth was my first glimpse into the peculiar nature of matter at the subatomic level.

Full of uncertainties

Scientists’ knowledge of the strong nuclear force is full of uncertainties. To learn more, physicists are going to the extremes of nuclear existence in pursuit of understanding the neutron dripline. The term refers to a boundary on a graph plotting the number of neutrons in a nucleus against the number of protons, but it reflects how many neutrons can be piled into a single nucleus before the particles begin to bounce off. This has preoccupied nuclear physicists for the past half century, and for many it is about more than understanding the nuclear force.

“We want to explore things as far away from what we know as possible,” said Alex Brown, a professor of physics at NSCL. “This is testing new aspects of our models that we are not able to see in any other way. What are the constituents of our world? How many nuclei exist? And how are they formed in the process of the evolution of the universe? All of that depends on where the dripline is."

Brown and his colleagues recently discovered three nuclei near the dripline that had never been observed before. Magnesium 40 with 12 protons and 28 neutrons was the goal of the experiment, and it was a hot find – pursued for more than twenty years without success. But most surprising were the two other nuclei—aluminum 42 and aluminum 43—that physicists thought should not have existed at all.

“The implication is that our models still have a long way to go,” said Brad Sherrill, university distinguished professor of physics at Michigan State University. “Surprises eventually lead to a deeper understanding of the science,” Sherrill said. “But at the moment, it’s just a surprise.”

One-hundred eighteen elements have been observed in the universe, but the neutron dripline has been found for only the first eight.

“You would think, if it’s so interesting to explore the dripline, why hasn’t it been done yet?” asks Thomas Baumann, a beam physicist at NSCL and lead researcher on the magnesium and aluminum study.

So Baumann and his colleagues started a search at NSCL.

Half of light-speed

In an experiment that ran earlier this year, the cyclotron accelerated a beam of calcium nuclei to nearly half the speed of light – fast enough to circle the Earth three times in one second. The nuclei collide into a tungsten target, producing a thick smattering of various nuclei and other particles. Only one out of billions—sometimes trillions or quadrillions—of the resultant nuclei is the one that researchers seek. Producing the desired nucleus by knocking out an exact number of protons and while leaving the neutrons untouched is akin to throwing a chocolate chip cookie at the wall and knocking out only chocolate chips.

A complex system of magnets downstream filters out the desired particles, and over 11 days, three particles of magnesium 40 were detected, a proportion comparable to finding three particles of sand in all the beaches of western North America.

“Everything has to work perfectly,” said Kirby Kemper, a collaborator from Florida State University. “It’s the golden amount, when everything you’ve worked for comes together and works – that’s what you live for as a scientist.”

The findings showed physicists that the neutron dripline is not as well understood as they thought, and to better define it they must venture into rarer nuclei.

For every nucleus closer to the dripline, Sherrill estimates that experimentally producing it would be 100 to 1000 times harder, requiring more powerful equipment or taking much more time.

“We made magnesium 40 in 11 days. Making magnesium 42 [with current technology] would take 1100 days. That’s 3 years of running. It’s kind of impossible,” Sherrill said. As a more realistic alternative, physicists stress the need to continue to develop new technology. “One hundred years from now when people are a lot smarter, this will all be really easy,” Sherill added. And so the pursuit proceeds.

Matt Johnson, NSCL staff engineer, inspects a 45-degree dipole magnet. The magnet, used to turn and separate nuclei, was installed in 2007, enabling researchers to continue pursuing exotic nuclei at the edge of existence.  

Are Scientists Playing God? It Depends on Your Religion

Are Scientists Playing God? It Depends on Your Religion

Viktor KoenNow that biologists in Oregon have reported using cloning to produce a monkey embryo and extract stem cells, it looks more plausible than before that a human embryo will be cloned and that, some day, a cloned human will be born. But not necessarily on this side of the Pacific.

American and European researchers have made most of the progress so far in biotechnology. Yet they still face one very large obstacle — God, as defined by some Western religions.

While critics on the right and the left fret about the morality of stem-cell research and genetic engineering, prominent Western scientists have been going to Asia, like the geneticists Nancy Jenkins and Neal Copeland, who left the National Cancer Institute and moved last year to Singapore.

Asia offers researchers new labs, fewer restrictions and a different view of divinity and the afterlife. In South Korea, when Hwang Woo Suk reported creating human embryonic stem cells through cloning, he did not apologize for offending religious taboos. He justified cloning by citing his Buddhist belief in recycling life through reincarnation.

When Dr. Hwang’s claim was exposed as a fraud, his research was supported by the head of South Korea’s largest Buddhist order, the Rev. Ji Kwan. The monk said research with embryos was in accord with Buddha’s precepts and urged Korean scientists not to be guided by Western ethics.

“Asian religions worry less than Western religions that biotechnology is about ‘playing God,’” says Cynthia Fox, the author of “Cell of Cells,” a book about the global race among stem-cell researchers. “Therapeutic cloning in particular jibes well with the Buddhist and Hindu ideas of reincarnation.”

You can see this East-West divide in maps drawn up by Lee M. Silver, a molecular biologist at Princeton. Dr. Silver, who analyzes clashes of spirituality and science in his book “Challenging Nature,” has been charting biotechnology policies around the world and trying to make spiritual sense of who’s afraid of what.

Most of southern and eastern Asia displays relatively little opposition to either cloned embryonic stem-cell research or genetically modified crops. China, India, Singapore and other countries have enacted laws supporting embryo cloning for medical research (sometimes called therapeutic cloning, as opposed to reproductive cloning intended to recreate an entire human being). Genetically modified crops are grown in China, India and elsewhere.

In Europe, though, genetically modified crops are taboo. Cloning human embryos for research has been legally supported in England and several other countries, but it is banned in more than a dozen others, including France and Germany.

In North and South America, genetically altered crops are widely used. But embryo cloning for research has been banned in most countries, including Brazil, Canada and Mexico. It has not been banned nationally in the United States, but the research is ineligible for federal financing, and some states have outlawed it.

Dr. Silver explains these patterns by dividing spiritual believers into three broad categories. The first, traditional Christians, predominate in the Western Hemisphere and some European countries. The second, which he calls post-Christians, are concentrated in other European countries and parts of North America, especially along the coasts. The third group are followers of Eastern religions.

“Most people in Hindu and Buddhist countries,” Dr. Silver says, “have a root tradition in which there is no single creator God. Instead, there may be no gods or many gods, and there is no master plan for the universe. Instead, spirits are eternal and individual virtue — karma — determines what happens to your spirit in your next life. With some exceptions, this view generally allows the acceptance of both embryo research to support life and genetically modified crops.”

By contrast, in the Judeo-Christian tradition, God is the master creator who gives out new souls to each individual human being and gives humans “dominion” over soul-less plants and animals. To traditional Christians who consider an embryo to be a human being with a soul, it is wrong for scientists to use cloning to create human embryos or to destroy embryos in the course of research.

But there is no such taboo against humans’ applying cloning and genetic engineering to “lower” animals and plants. As a result, Dr. Silver says, cloned animals and genetically modified crops have not become a source of major controversy for traditional Christians. Post-Christians are more worried about the flora and fauna.

“Many Europeans, as well as leftists in America,” Dr. Silver says, “have rejected the traditional Christian God and replaced it with a post-Christian goddess of Mother Nature and a modified Christian eschatology. It isn’t a coherent belief system. It might or might not incorporate New Age thinking. But deep down, there’s a view that humans shouldn’t be tampering with the natural world.”

Hence the opposition to genetically modified food.

Because post-Christians do not necessarily share the biblical view of an omnipotent deity with the sole power to create souls, Dr. Silver says, they are less worried about scientists “playing God” in the laboratory with embryos. In places like California, residents have voted not only to allow embryo cloning for research, but also to finance it.

But sometimes the reverence for the natural world extends to embryos, leading to unlikely alliances. When conservative intellectuals like Francis Fukyama campaigned for Congress to ban embryo cloning, some environmental activists like Jeremy Rifkin joined them. A Green Party leader in Germany, Voker Beck, referred to cloned embryonic stem-cell research as “veiled cannibalism.”

Of course, many critics of biotechnology do not explicitly use religious dogma to justify their opposition. Countries like the United States, after all, are supposed to be guided by secular constitutions, not sectarian creeds. So opponents of genetically modified foods focus on the possible dangers to ecosystems and human health, and committees of scientists try to resolve the debate by conducting risk analysis.

The outcome hinges more on beliefs than on scientific data. A study finding that genetically modified foods are safe might reassure traditional Christians in Kansas, but it won’t stop post-Christians in Stockholm from worrying about “Frankenfood.”

Similarly, some leading opponents of embryo research for cloning, like Leon Kass, say they are defending not Judeo-Christian beliefs, but “human dignity.” Dr. Kass, former chairman of the President’s Council on Bioethics, says the special status of humans described in the Book of Genesis should be heeded not because of the Bible’s authority, but because the message reflects a “cosmological truth.”

It is not so easy, though, to defend supposedly self-evident truths about human nature that are not evident to a large portion of humanity. Conservatives in the House of Representatives managed to pass a bill banning Americans from going overseas for stem-cell treatments derived through embryo cloning. But the bill didn’t pass the Senate.

It is by no means certain that this type of stem-cell research will ever yield treatments for diseases like Parkinson’s, but should that happen, it is hard to see how any Congress — or any law — could stop people from seeking cures.

The prospect of cloning children is much more distant, particularly now that researchers are becoming optimistic about obtaining stem cells without using embryos. For now, scientists throughout the world say they do not even want to contemplate reproductive cloning because of the risks to the child. And public-opinion polls do not show much support for it anywhere.

Even if human cloning becomes safe, there may never be much demand for it, because most people will prefer having children the old-fashioned way.

But some people may desperately want a cloned child — perhaps to replace one who died or to provide lifesaving bone marrow for a sibling — and won’t be dissuaded, no matter how many Christians or post-Christians try to stop them. To reach this frontier, they may just go east.