New Planet May Be Among Most Earthlike—Weather Permitting

An artist's rendering of an Earthlike alien planet.

Illustration courtesy L. Calçada, ESO

"A new planet found about 36 light-years away could be one of the most Earthlike worlds yet—if it has enough clouds, a new study says.

The unpoetically named HD85512b was discovered orbiting an orange dwarfstar in the constellation Vela. Astronomers found the planet using the European Southern Observatory's High Accuracy Radial velocity Planet Searcher, or HARPS, instrument in Chile.

Radial velocity is a planet-hunting technique that looks for wobbles in a star's light, which can indicate the gravitational tugs of orbiting worlds.

The HARPS data show that the planet is 3.6 times the mass of Earth, and the new world orbits its parent star at just the right distance for water to be liquid on the planet's surface—a trait scientists believe is crucial for life as we know it.

(Related: "NASA Finds Smallest Earthlike Planet Outside Solar System.")

"The distance is exactly the limit where you want to be to have liquid water," said study leader Lisa Kaltenegger of the Harvard-Smithsonian Center for Astrophysics and the Max Planck Institute for Astronomy.

"If you scale it to our system, it's a bit further out than Venus is to our sun." At that distance, the planet likely receives a bit more solar energy from its star than Earth does from the sun. (Explore an interactive solar system.)

But Kaltenegger and colleagues calculate that a cloud cover of at least 50 percent would reflect enough of the energy back into space to prevent overheating.

On average, Earth has 60 percent cloud cover, so partly cloudy skies on HD85512b are "not out of the question," she said.

Of course, clouds of water vapor depend on the presence of an atmospheresimilar to Earth's, something that can't be detected on such distant planets with current instruments.

Models of planet formation predict that planets with more than ten times Earth's mass should have atmospheres dominated by hydrogen and helium, Kaltenegger said. Less massive worlds—including HD85512b—are more likely to have Earthlike atmospheres, made mostly of nitrogen and oxygen.

(Related: "Saturn Moon Has Oxygen Atmosphere.")

New World "A Strong Candidate" for Habitability

So far, the newly detected planet is only the second rocky world outside our solar system to be confirmed in its star's habitable zone—the region around a star that's not too hot and not too cold for liquid water.

The other contender, planet Gliese 581d, was previously discovered using the HARPS instrument. This world lies just on the cool edge of its star's habitable zone. (See "Most Earthlike Planet Yet Found May Have Liquid Oceans.")

Another promising planet, Gliese 581g, was discovered in 2010 and dubbed the most Earthlike planet yet. But controversy surrounds the claim, with some experts declaring that the entire planet is actually a data glitch.

Manfred Cuntz, director of the astronomy program at the University of Texas, Arlington, noted that more information is needed before anyone can speculate whether aliens are wandering around the newfound planet.

"It's not their fault no extra information [about the planet's atmosphere] is available right now," Cuntz said of the research team. "It looks like this is a strong candidate, in principle."

In addition to size and location, HD85512b has two other points in its favor for potentially harboring life, Cuntz said.

The planet's orbit is nearly circular, which would provide a stable climate, and its parent star, HD85512, is older—and therefore less active—than our sun, which would lower the likelihood of electromagnetic storms damaging the planet's atmosphere.

(See "'Nightmare' Star Flares Dim Odds for Alien Life?")

Not only that, but in principle, the age of the system—5.6 billion years—"gives life a chance to originate and develop," he said. By contrast, our own solar system is thought to be about 4.6 billion years old.

New Planet a Great Place for Yoga?

Given current limits on space travel, it's unlikely for now that humans will get to visit HD85512b.

But if we could get there, the newfound planet might seem like a fairly alien world: muggy, hot, and with a gravity 1.4 times that of Earth's, study leader Kaltenegger said.

On the bright side, "hot yoga might be one of the things you don't have to pay for there," she quipped.

The paper describing HD85512b appears online at arXiv.org and has been accepted for publication in the journal Astronomy and Astrophysics." - Rachel Kaufman, for National Geographic News.

Published August 30, 2011

Black Death Bacterium Identified: Genetic Analysis of Medieval Plague Skeletons Shows Presence of Yersinia Pestis Bacteria

Yersinia pestis, direct fluorescent antibody stain (DFA), 200x magnification. (Credit: CDC/Courtesy of Larry Stauffer, Oregon State Public Health Laboratory)

ScienceDaily (Aug. 29, 2011) — "A team of German and Canadian scientists has shown that today's plague pathogen has been around at least 600 years.

The Black Death claimed the lives of one-third of Europeans in just five years from 1348 to 1353. Until recently, it was not certain whether the bacterium Yersinia pestis -- known to cause the plague today -- was responsible for that most deadly outbreak of disease ever. Now, the University of Tübingen's Institute of Scientific Archaeology and McMaster University in Canada have been able to confirm that Yersinia pestis was behind the great plague.

The results of the research are published in the Proceedings of the National Academy of Sciences.

Previous genetic tests indicating that the bacterium was present in medieval samples had previously been dismissed as contaminated by modern DNA or the DNA of bacteria in the soil. Above all, there was doubt because the modern plague pathogen spreads much more slowly and is less deadly than the medieval plague -- even allowing for modern medicine.

The international team of researchers has for the first time been able to decode a circular genome important for explaining the virulence of Y. pestis. It is called pPCP1 plasmid and comprises about 10,000 positions in the bacterium's DNA. The sample was taken from skeletons from a London plague cemetery. The working group in Tübingen, led by Dr. Johannes Krause used a new technique of "molecular fishing" -- enriching plague DNA fragments from tooth enamel and sequencing them using the latest technology. In this way, the fragments were connected up into a long genome sequence -- which turned out to be identical to modern-day plague pathogens. "That indicates that at least this part of the genetic information has barely changed in the past 600 years," says Krause.

The researchers were also able to show that the plague DNA from the London cemetery was indeed medieval. To do that, they examined damage to the DNA which only occurs in old DNA -- therefore excluding the possibility of modern contamination. "Without a doubt, the plague pathogen known today as Y. pestis was also the cause of the plague in the Middle Ages," says Krause, who is well known for his DNA sequencing of ancient hominin finds, which help trace relationships between types of prehistoric man and modern humans." - ScienceDaily.com

Humans Could Have Geomagnetic Sight

"The ability to see Earth’s magnetic field, thought to be restricted to sea turtles and swallows and other long-distance animal navigators, may also reside in human eyes.

Tests of cryptochrome 2, a key protein component of geomagnetic perception, found that its human version restored geomagnetic orientation in cryptochrome-deficient fruit flies.

Flies are a long, long way from people, but that the protein worked at all is impressive. There’s also a whole lot of it in our eyes.

“Could humans have this cryptochrome heavily expressed in the retina as a light-sensitive magnetoreceptor?” said University of Massachusetts neuroscientist Steven Reppert, lead author of a June 21 Nature Communications cryptochrome study. “We don’t know if the molecule will do this in the human retina, but this suggests the possibility.”

Reppert, whose laboratory specializes in the biological mechanisms underlying long-distance butterfly migration, showed three years ago that cryptochrome allowed fruit flies to geomagnetically orient themselves using light.

Before then, cryptochrome’s navigational role was a matter of inference and proposition. Since then, researchers have described how cryptochrome seems to be a quantum compass that detects infinitesimally subtle, geomagnetically-induced variations in the spin of electrons struck by photons. From those variations, animals seem able to determine their orientation in relation to Earth’s magnetic field.

Many gaps still remain in cryptochrome theory, but it’s generally thought that the cryptochrome system may be active across the animal kingdom, from fish to reptiles to birds. Humans, however, were thought to be an exception. Our own cryptochrome is considered a piece of circadian machinery, part of our molecular clock rather than any optical compass.

The new study, however, suggests that cryptochrome may be more than a clock. Seeking to test how a vertebrate cryptochrome would work in fruit flies, Reppert decided to use the human version. His team engineered flies to be cryptochrome-deficient: They struggled to orient within a magnetically-charged maze. When the researchers spliced human cryptochrome into the flies, they again found their bearings.

‘We can’t show that it will do the same in humans, but it sure restored geomagnetic sight in the flies.’

“This is a very exciting paper,” said Klaus Schulten, a University of Illinois at Urbana-Champaign biophysicist and cryptochrome research pioneer who was not involved in the new study. According to Schulten, the findings add even more support for the general role of cryptochrome in vertebrates, and of course raise questions about cryptochrome’s role in people.

“We can’t show that it will do the same in humans, but it sure restored geomagnetic sight in the flies,” said Reppert.

Whether humans can sense geomagnetism is somewhat controversial. In the 1980s, research by British zoologist Robin Baker suggested that humans have a magnetic sense, but the findings proved difficult to replicate. More recently, however, work by German researchers hints at geomagnetic effects on vision.

Whether any of this is linked to high levels of cryptochrome in human eyes — and, if so, whether that quantum compass system still works for us — is completely speculative, but it’s speculation that Reppert welcomes. “It’s perfectly reasonable to think that humans have a magnetosensing response,” he said. “Maybe we’ve been looking at it in a way that’s not been fruitful in the past.”

Schulten, however, thinks evolution might have traded geomagnetic orientation for longevity. His own research suggests that the cryptochrome compass needs superoxide, a type of free radical oxygen molecule, to work. Free radicals tend to destroy DNA. That’s fine for a relatively short-lived animal, but not for one that intends to live for decades.

Nevertheless, said Schulten, “it might be that we humans, along with many other animals, might have been capable a long, long time ago of orienting ourselves.”

Reppert himself is now concentrating on how brains read their cryptochrome compass. “At the most fundamental level, we’re interested in how cryptochrome information is transferred to the nervous system,” he said. “Nobody knows how that occurs.”

Top image: GaelG, Flickr." - By Brandon Keim, Wired.

Rare disease causes genetic mutation where people are born without fingerprints. (Click here)

Photo credit: National Geographic

Scientists bear down on "Intelligence genes"

Photo credit: Metro News

"Death Dance" Stars Found—May Help Prove Einstein Right; Exotic pair may allow scientists to "probe for extreme gravity."

Two orbiting white dwarfs radiate gravitational waves, as seen in an artist's conception.

Illustration courtesy Tod Strohmayer/CXC/NASA and Dana Berry/CXC

Andrew Fazekas

for National Geographic News

Published July 19, 2011

A pair of aging stars discovered 3,000 light-years away is locked in a "dance" of death—a union that will end in their collision and a possiblesupernova, astronomers say.

The binary star system consists of two white dwarfs—the burnt-out cores of sunlike stars. The white dwarfs are gradually spiraling toward each other at breakneck speeds of 370 miles (595 kilometers) a second, and they're destined to merge in 900,000 years.

But astronomers hope that, before the collision, the spinning stars will help scientists test Einstein's general theory of relativity and even reveal the origins of an entire class of supernovae. (Related: "Einstein's Gravity Confirmed on a Cosmic Scale.")

"What is so incredible is that this exotic pair of Earth- and Neptune-sized stars are orbiting each other at only a third of our Earth-moon distance, circling each other every 12 minutes," said study leader Warren Brown, an astronomer at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts.

"And because there is no interaction—or star matter streaming between them—we may have a unique stellar laboratory here to look for effects of general relativity and probe for extreme gravity."

But the newfound star pair is unique in that they don't swap matter as they spin, providing a "clean clock" to measure the effects of gravitational waves, Brown said.

"There are lots of stellar pairs in the universe, but all are interacting and exchanging matter with one another because they are so close together."

That "complicates their interpretation, because you typically don't see either star, except for the light coming from the matter that is going back and forth between the stars."

With a noninteracting pair, astronomers can precisely measure the change in the orbital period of the stars as they spiral toward each other.

Astrophysicist Gijs Nelemans, of Radboud University in the Netherlands, added that the new white dwarf system is probably a strong gravitational wave source, one that may soon be detectable by a gravity-wave space satellite called LISA, which could be launched around 2020.

"The most exciting aspect is that the change in the orbital period as it emits gravitational waves can actually be measured," said Nelemans, who was not involved in the new research.

"That means we will not only indirectly test general relativity, but also directly measure the predicted gravitational waves, which has never been done before," he said.

"Such a mission would truly open a new way to study the universe."

Newfound Pair May Illuminate Star Evolution, Death

The discovery also could help astronomers understand star evolution and death. It's long been speculated, for instance, that white dwarf collisions may produce Type Ia supernovae, which are thought to be caused when matter from a companion star is dumped onto a white dwarf, increasing the dwarf's mass beyond a set physical limit and igniting a thermonuclear explosion.

When the two newfound stars merge, according to current models, the result may be one supermassive white dwarf or an unusually faint stellar blast called an underluminous supernova. 

Ring of star debris

"If this is the progenitor of these rare subclass of supernova, we expect to be finding these exotic pairs at the same frequency as the supernova. We'll have to wait and see what our survey comes up with," study leader Brown explained.

Initial measurements were made in March, but now the binary system has moved almost directly behind the sun from our perspective on Earth, making the pair currently invisible to telescopes.

As a result, Brown and his team will have to wait until fall to measure the expected shortening of the orbital period.

"Stars merging in less than a million years is really a blink of an eye in cosmic time scales," Brown said. "Just the fact that we found something like this—and it exists—is interesting for astronomers."

- National Geographic

Alert the Vatican, "Angels & Demons" might still happen! (Click here)

CERN creates and traps antimatter in groundbreaking experiment

Supernova discovered in whirlpool galaxy (Click here)

Hubble Space Telescope image shows off the Whirlpool galaxy as it looked before this week's supernova eruption. credit: STScI/AURA

Sky chart showing M 51 is located just off the Big Dipper handle; Credit: YourSky software

Newly discovered supernova appears to blink in before and after photos of the Whirlpool galaxy. credit: Stéphane Lamotte Bailey

Photo credit: National Geographic

Hot stuff! (Jupiter moon) (Click here!)

Planets apparently swing - I mean spin - both ways.

Photo credit: "24H Ottawa" May 13-15th 2011