Tag: linked (page 2 of 5)

Chicxulub Dinosaur-Killer Asteroid Impact To Be Probed For Answers To Extinction Mysteries

April 13, 2015 / / 0 Comments

Excerpt from techtimes.comScientists are seeking a core sample from the Chicxulub crater that marks the remains of an asteroid impact which ended the age of the dinosaurs nearly 66 million years ago.That geological feature will be probed by scientist...

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New spin on Saturn’s peculiar, err, spin

March 27, 2015 / / 0 Comments

 Excerpt from spacedaily.comAccording to the new method, Saturn's day is 10 hours, 32 minutes and 44 seconds long. Tracking the rotation speed of solid planets, like the Earth and Mars, is a relatively simple task: Just measure the time it tak...

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Circular thinking: Stonehenge’s origin is subject of new theory

March 24, 2015 / / 0 Comments




Excerpt from theguardian.com

Whether it was a Druid temple, an astronomical calendar or a centre for healing, the mystery of Stonehenge has long been a source of speculation and debate. Now a dramatic new theory suggests that the prehistoric monument was in fact “an ancient Mecca on stilts”.

The megaliths would not have been used for ceremonies at ground level, but would instead have supported a circular wooden platform on which ceremonies were performed to the rotating heavens, the theory suggests.

Julian Spalding, an art critic and former director of some of the UK’s leading museums, argues that the stones were foundations for a vast platform, long since lost – “a great altar” raised up high towards the heavens and able to support the weight of hundreds of worshippers.

“It’s a totally different theory which has never been put forward before,” Spalding told the Guardian. “All the interpretations to date could be mistaken. We’ve been looking at Stonehenge the wrong way: from the earth, which is very much a 20th-century viewpoint. We haven’t been thinking about what they were thinking about.”

Since Geoffrey of Monmouth wrote in the 12th century that Merlin had flown the stones from Ireland, theories on Stonehenge, from plausible to absurd, have abounded. In the last decade alone, the monument has been interpreted as “the prehistoric Lourdes” where people brought the sick to be healed by the power of the magic bluestones from Wales and as a haunted place of the dead contrasting with seasonal feasts for the living at nearby Durrington Walls. 

The site pored over by archaeologists for centuries still produces surprises, including the outline of stones now missing, which appeared in the parched ground in last summer’s drought and showed that the monument was not left unfinished as some had believed, but was once a perfect circle.

Spalding, who is not an archaeologist, believes that other Stonehenge theorists have fallen into error by looking down instead of up. His evidence, he believes, lies in ancient civilisations worldwide. As far afield as China, Peru and Turkey, such sacred monuments were built high up, whether on manmade or natural sites, and in circular patterns possibly linked to celestial movements.

He said: “In early times, no spiritual ceremonies would have been performed on the ground. The Pharaoh of Egypt and the Emperor of China were always carried – as the Pope used to be. The feet of holy people were not allowed to touch the ground. We’ve been looking at Stonehenge from a modern, earth-bound perspective.”
“All the great raised altars of the past suggest that the people who built Stonehenge would never have performed celestial ceremonies on the lowly earth,” he went on. “That would have been unimaginably insulting to the immortal beings, for it would have brought them down from heaven to bite the dust and tread in the dung.”

Spalding’s theory has not met with universal approval. Prof Vincent Gaffney, principal investigator on the Stonehenge Hidden Landscapes Project at Bradford University, said he held “a fair degree of scepticism” and Sir Barry Cunliffe, a prehistorian and emeritus professor of European archaeology at Oxford University, said: “He could be right, but I know of no evidence to support it”.
The archaeologist Aubrey Burl, an authority on prehistoric stone circles, said: “There could be something in it. There is a possibility, of course. Anything new and worthwhile about Stonehenge is well worth looking into, but with care and consideration.”

On Monday Spalding publishes his theories in a new book, titled Realisation: From Seeing to Understanding – The Origins of Art. It explores our ancestors’ understanding of the world, offering new explanations of iconic works of art and monuments.

Stonehenge, built between 3000 and 2000BC, is England’s most famous prehistoric monument, a UNESCO World Heritage site on Salisbury Plain in Wiltshire that draws more than 1 million annual visitors. It began as a timber circle, later made permanent with massive blocks of stone, many somehow dragged from dolerite rock in the Welsh mountains. Spalding believes that ancient worshippers would have reached the giant altar by climbing curved wooden ramps or staircases.

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What happens to your body when you give up sugar?

March 4, 2015 / / 0 Comments





Excerpt from independent.co.uk
By Jordan Gaines Lewis


In neuroscience, food is something we call a “natural reward.” In order for us to survive as a species, things like eating, having sex and nurturing others must be pleasurable to the brain so that these behaviours are reinforced and repeated.
Evolution has resulted in the mesolimbic pathway, a brain system that deciphers these natural rewards for us. When we do something pleasurable, a bundle of neurons called the ventral tegmental area uses the neurotransmitter dopamine to signal to a part of the brain called the nucleus accumbens. The connection between the nucleus accumbens and our prefrontal cortex dictates our motor movement, such as deciding whether or not to taking another bite of that delicious chocolate cake. The prefrontal cortex also activates hormones that tell our body: “Hey, this cake is really good. And I’m going to remember that for the future.”
Not all foods are equally rewarding, of course. Most of us prefer sweets over sour and bitter foods because, evolutionarily, our mesolimbic pathway reinforces that sweet things provide a healthy source of carbohydrates for our bodies. When our ancestors went scavenging for berries, for example, sour meant “not yet ripe,” while bitter meant “alert – poison!”
Fruit is one thing, but modern diets have taken on a life of their own. A decade ago, it was estimated that the average American consumed 22 teaspoons of added sugar per day, amounting to an extra 350 calories; it may well have risen since then. A few months ago, one expert suggested that the average Briton consumes 238 teaspoons of sugar each week.
Today, with convenience more important than ever in our food selections, it’s almost impossible to come across processed and prepared foods that don’t have added sugars for flavour, preservation, or both.
These added sugars are sneaky – and unbeknown to many of us, we’ve become hooked. In ways that drugs of abuse – such as nicotine, cocaine and heroin – hijack the brain’s reward pathway and make users dependent, increasing neuro-chemical and behavioural evidence suggests that sugar is addictive in the same way, too.

Sugar addiction is real

Anyone who knows me also knows that I have a huge sweet tooth. I always have. My friend and fellow graduate student Andrew is equally afflicted, and living in Hershey, Pennsylvania – the “Chocolate Capital of the World” – doesn’t help either of us. But Andrew is braver than I am. Last year, he gave up sweets for Lent. “The first few days are a little rough,” Andrew told me. “It almost feels like you’re detoxing from drugs. I found myself eating a lot of carbs to compensate for the lack of sugar.”
There are four major components of addiction: bingeing, withdrawal, craving, and cross-sensitisation (the notion that one addictive substance predisposes someone to becoming addicted to another). All of these components have been observed in animal models of addiction – for sugar, as well as drugs of abuse.
A typical experiment goes like this: rats are deprived of food for 12 hours each day, then given 12 hours of access to a sugary solution and regular chow. After a month of following this daily pattern, rats display behaviours similar to those on drugs of abuse. They’ll binge on the sugar solution in a short period of time, much more than their regular food. They also show signs of anxiety and depression during the food deprivation period. Many sugar-treated rats who are later exposed to drugs, such as cocaine and opiates, demonstrate dependent behaviours towards the drugs compared to rats who did not consume sugar beforehand.
Like drugs, sugar spikes dopamine release in the nucleus accumbens. Over the long term, regular sugar consumption actually changes the gene expression and availability of dopamine receptors in both the midbrain and frontal cortex. Specifically, sugar increases the concentration of a type of excitatory receptor called D1, but decreases another receptor type called D2, which is inhibitory. Regular sugar consumption also inhibits the action of the dopamine transporter, a protein which pumps dopamine out of the synapse and back into the neuron after firing.
In short, this means that repeated access to sugar over time leads to prolonged dopamine signalling, greater excitation of the brain’s reward pathways and a need for even more sugar to activate all of the midbrain dopamine receptors like before. The brain becomes tolerant to sugar – and more is needed to attain the same “sugar high.”

Sugar withdrawal is also real

Although these studies were conducted in rodents, it’s not far-fetched to say that the same primitive processes are occurring in the human brain, too. “The cravings never stopped, [but that was] probably psychological,” Andrew told me. “But it got easier after the first week or so.”
In a 2002 study by Carlo Colantuoni and colleagues of Princeton University, rats who had undergone a typical sugar dependence protocol then underwent “sugar withdrawal.” This was facilitated by either food deprivation or treatment with naloxone, a drug used for treating opiate addiction which binds to receptors in the brain’s reward system. Both withdrawal methods led to physical problems, including teeth chattering, paw tremors, and head shaking. Naloxone treatment also appeared to make the rats more anxious, as they spent less time on an elevated apparatus that lacked walls on either side.
Similar withdrawal experiments by others also report behaviour similar to depression in tasks such as the forced swim test. Rats in sugar withdrawal are more likely to show passive behaviours (like floating) than active behaviours (like trying to escape) when placed in water, suggesting feelings of helplessness.
A new study published by Victor Mangabeira and colleagues in this month’s Physiology & Behavior reports that sugar withdrawal is also linked to impulsive behaviour. Initially, rats were trained to receive water by pushing a lever. After training, the animals returned to their home cages and had access to a sugar solution and water, or just water alone. After 30 days, when rats were again given the opportunity to press a lever for water, those who had become dependent on sugar pressed the lever significantly more times than control animals, suggesting impulsive behaviour.
These are extreme experiments, of course. We humans aren’t depriving ourselves of food for 12 hours and then allowing ourselves to binge on soda and doughnuts at the end of the day. But these rodent studies certainly give us insight into the neuro-chemical underpinnings of sugar dependence, withdrawal, and behaviour.
Through decades of diet programmes and best-selling books, we’ve toyed with the notion of “sugar addiction” for a long time. There are accounts of those in “sugar withdrawal” describing food cravings, which can trigger relapse and impulsive eating. There are also countless articles and books about the boundless energy and new-found happiness in those who have sworn off sugar for good. But despite the ubiquity of sugar in our diets, the notion of sugar addiction is still a rather taboo topic.
Are you still motivated to give up sugar? You might wonder how long it will take until you’re free of cravings and side-effects, but there’s no answer – everyone is different and no human studies have been done on this. But after 40 days, it’s clear that Andrew had overcome the worst, likely even reversing some of his altered dopamine signalling. “I remember eating my first sweet and thinking it was too sweet,” he said. “I had to rebuild my tolerance.”
And as regulars of a local bakery in Hershey – I can assure you, readers, that he has done just that.
Jordan Gaines Lewis is a Neuroscience Doctoral Candidate at Penn State College of Medicine

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Air Force: Military Satellite Explosion Linked to Power System Failure

March 3, 2015 / / 0 Comments

Artist's concept of a Defense Meteorological Satellite System (DMSP) military weather spacecraft.


Excerpt from nbcnews.com

The military weather satellite that exploded in orbit last month apparently died of old age, U.S. Air Force officials say. 

While investigators continue to study the dramatic Feb. 3 death of Defense Meteorological Satellite Program Flight 13 (DMSP-F13), the signs currently point not to a collision with a piece of space junk or other external cause but rather to an issue aboard the spacecraft, which launched in 1995. 

"Basically, the spacecraft was 20 years old and experienced what appears to be a catastrophic event associated with a power system failure," Andy Roake, chief of the Current Operations Division at Air Force Space Command Public Affairs in Colorado Springs, told Space.com. 


Investigators think that failure by itself probably blew apart DMSP-F13 — which occupied a sun-synchronous polar orbit about 500 miles (800 kilometers) above Earth — generating the cloud of debris that the Air Force's Joint Space Operations Center (JSpOC) has detected near the satellite. (To date, 43 pieces of debris have been identified.) 

Indeed, Air Force officials have said that the military weather satellite explosion was preceded by a sudden spike in the power system's temperature, "followed by an unrecoverable loss of attitude control." It was first reported by SpaceNews, a Space.com partner, on Feb. 27. 

DMSP-F13 launched in March 1995 and last year surpassed 100,000 orbits around Earth. The satellite contributed key data to a number of U.S. military operations overseas.

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How Would the World Change If We Found Alien Life?

February 8, 2015 / / 0 Comments







Excerpt from space.com
By by Elizabeth Howell

 In 1938, Orson Welles narrated a radio broadcast of "War of the Worlds" as a series of simulated radio bulletins of what was happening in real time as Martians arrived on our home planet. The broadcast is widely remembered for creating public panic, although to what extent is hotly debated today.

Still, the incident serves as an illustration of what could happen when the first life beyond Earth is discovered. While scientists might be excited by the prospect, introducing the public, politicians and interest groups to the idea could take some time.

How extraterrestrial life would change our world view is a research interest of Steven Dick, who just completed a term as the Baruch S. Blumberg NASA/Library of Congress Chair of Astrobiology. The chair is jointly sponsored by the NASA Astrobiology Program and the John W. Kluge Center, at the Library of Congress. 


Dick is a former astronomer and historian at the United States Naval Observatory, a past chief historian for NASA, and has published several books concerning the discovery of life beyond Earth. To Dick, even the discovery of microbes would be a profound shift for science.

"If we found microbes, it would have an effect on science, especially biology, by universalizing biology," he said. "We only have one case of biology on Earth. It's all related. It's all DNA-based. If we found an independent example on Mars or Europa, we have a chance of forming a universal biology."

Dick points out that even the possibilities of extraterrestrial fossils could change our viewpoints, such as the ongoing discussion of ALH84001, a Martian meteorite found in Antarctica that erupted into public consciousness in 1996 after a Science article said structures inside of it could be linked to biological activity. The conclusion, which is still debated today, led to congressional hearings.

"I've done a book about discovery in astronomy, and it's an extended process," Dick pointed out. "It's not like you point your telescope and say, 'Oh, I made a discovery.' It's always an extended process: You have to detect something, you have to interpret it, and it takes a long time to understand it. As for extraterrestrial life, the Mars rock showed it could take an extended period of years to understand it."


ALH84001 Meteorite
The ALH84001 meteorite, which in a 1996 Science publication was speculated to be host to what could be ancient Martian fossils. That finding is still under dispute today.

Mayan decipherments

In his year at the Library of Congress, Dick spent time searching for historical examples (as well as historical analogies) of how humanity might deal with first contact with an extraterrestrial civilization. History shows that contact with new cultures can go in vastly different directions.

Hernan Cortes' treatment of the Aztecs is often cited as an example of how wrong first contact can go. But there were other efforts that were a little more mutually beneficial, although the outcomes were never perfect. Fur traders in Canada in the 1800s worked closely with Native Americans, for example, and the Chinese treasure fleet of the 15th Century successfully brought its home culture far beyond its borders, perhaps even to East Africa.

Even when both sides were trying hard to make communication work, there were barriers, noted Dick.

"The Jesuits had contact with Native Americans," he pointed out. "Certain concepts were difficult, like when they tried to get across the ideas of the soul and immortality."



A second look by the Mars Global Surveyor at the so-called Viking “Face on Mars” in Cydonia revealed a more ordinary-looking hill, showing that science is an extended process of discovery.


Indirect contact by way of radio communications through the Search for Extraterrestrial Intelligence (SETI), also illustrates the challenges of transmitting information across cultures. There is historical precedence for this, such as when Greek knowledge passed west through Arab translators in the 12th Century. This shows that it is possible for ideas to be revived, even from dead cultures, he said.

It's also quite possible that the language we receive across these indirect communications would be foreign to us. Even though mathematics is often cited as a universal language, Dick said there are actually two schools of thought. One theory is that there is, indeed, one kind of mathematics that is based on a Platonic idea, and the other theory is that mathematics is a construction of the culture that you are in. 

"There will be a decipherment process. It might be more like the Mayan decipherments," Dick said.


The ethics of contact

As Dick came to a greater understanding about the potential c impact of extraterrestrial intelligence, he invited other scholars to present their findings along with him. Dick chaired a two-day NASA/Library of Congress Astrobiology Symposium called "Preparing for Discovery," which was intended to address the impact of finding any kind of life beyond Earth, whether microbial or some kind of intelligent, multicellular life form.

The symposium participants discussed how to move beyond human-centered views of defining life, how to understand the philosophical and theological problems a discovery would bring, and how to help the public understand the implications of a discovery.

"There is also the question of what I call astro-ethics," Dick said. "How do you treat alien life? How do you treat it differently, ranging from microbes to intelligence? So we had a philosopher at our symposium talking about the moral status of non-human organisms, talking in relation to animals on Earth and what their status is in relation to us."

Dick plans to collect the lectures in a book for publication next year, but he also spent his time at the library gathering materials for a second book about how discovering life beyond Earth will revolutionize our thinking.

"It's very farsighted for NASA to fund a position like this," Dick added. "They have all their programs in astrobiology, they fund the scientists, but here they fund somebody to think about what the implications might be. It's a good idea to do this, to foresee what might happen before it occurs."

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As Dawn spacecraft closes in on Ceres, things start to look ‘rough’

January 28, 2015 / / 0 Comments


Ceres: Dawn spies dwarf planet
This image, taken 147,000 miles from Ceres by NASA's Dawn spacecraft, is part of a series of views representing the best look so far at the dwarf planet. The spacecraft is set to enter orbit March 6. (NASA)

Eat your heart out, Hubble! NASA’s Dawn spacecraft is in the home stretch of its journey to Ceres and has snapped the best images yet of the dwarf planet. Grainy as they are, the new views of the 590-mile-wide world are already turning up unexpected features on the surface.
“What we expect at Ceres is to be surprised, so it’s getting off to a good start,” said deputy principal investigator Carol Raymond.
The images, taken 147,000 miles from Ceres on Jan. 25, are 30% higher-resolution than the images taken by NASA’s Hubble Space Telescope in 2003 and 2004. They measure 43 pixels wide, a significant improvement over Dawn’s images from earlier this month, which were 27 pixels across.
The images show significant brightness and darkness variations over the surface – particularly a bright spot gleaming in the northern hemisphere and darker spots in the southern hemisphere. While the scientists were aware of those major spots, they weren’t expecting to see quite so much texture on the surface, said Raymond, a geophysicist at the Jet Propulsion Laboratory.

Ceres is fairly warm by ice-world standards; temperatures generally range from 180 to 240 Kelvin (or minus-136 degrees Fahrenheit to minus-28 degrees Fahrenheit), Raymond said. Theoretically, the ice on Ceres’ surface should start to flow as it warms up, smoothing out any bumps such as those from impact craters. But the brightness variations across the surface make it appear very rough, she said.
“This is just starting to illuminate the fact that Ceres is one of these unique bodies that has astrobiological potential ... and it’s just continued to become more intriguing as we’ve been marching inexorably closer,” she added.

Ceres was not the first stop in Dawn’s 3-billion-mile journey. The first was the protoplanet Vesta, which is vastly different from its fellow mega-asteroid, Ceres. Where Vesta is dry and lumpy, Ceres is icy and round, massive enough to have been pulled into a planet-like shape. Scientists want to find out why these two space-fossils from the early solar system ended up with such different geophysical life stories.
At least with Vesta, there were meteorites linked to the asteroid that planetary scientists can study, Raymond pointed out. For Ceres, there are no such space rocks found on Earth – so the researchers have somewhat less of an idea of what to expect.

“I am excited,” Raymond said. “Just having had the wild ride at Vesta, I’m also just in awe of what’s going to happen. It’s going to be amazing.”

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Meteorite is ‘hard drive’ from space ~ Researchers decode ancient recordings from asteroid ~ BBC

January 21, 2015 / / 0 Comments


Pallasite meteorite
The Esquel meteorite consists of gem-quality crystals embedded in metal.



Excert from bbc.com

Researchers have decoded ancient recordings from fragments of an asteroid dating back billions of years to the start of the Solar System. 

They found tiny "space magnets" in meteorites which retain a memory of the birth and death of the asteroid's core.
Like the data recorded on the surface of a computer hard drive, the magnetic signals written in the space rock reveal how Earth's own metallic core and magnetic field may one day die.

The work appears in Nature journal.

Using a giant X-ray microscope, called a synchrotron, the team was able to read the signals that formed more than four-and-a-half billion years ago, soon after the birth of the Solar System.

“Start Quote

It's like a cosmic archaeological mission”
Dr James Bryson University of Cambridge
The meteorites are pieces of a parent asteroid that originally came from asteroid belt, between Mars and Jupiter.
They represents the left-over fragments of a planet that failed to form. The magnetic recording within it traps a signal of the precise moments when an iron-rich core formed in the asteroid as well as when it froze, killing its magnetic field.
The new picture of metallic core solidification in the asteroid provide clues about the magnetic field and iron-rich core of Earth.
Core values "Ideas about how the Earth's core evolved through [our planet's] history are really changing at the moment," lead researcher Dr Richard Harrison, from the University of Cambridge, told BBC News.
"We believe that Earth's magnetic field is linked to core solidification. Earth's solid inner core may have started to form at very interesting time in terms of the evolution of life on Earth.
"By studying an asteroid we get to see this in fast forward. We can see the start of core solidification in the magnetic records as well as its end, and start to think about how these processes work on Earth."

Magnetic fieldThe Earth's magnetic field will likely die off when the core completely freezes
The meteorites studied by the team originally fell to Earth in Argentina, and are composed of gem-quality crystals enclosed in a metallic matrix of iron and nickel. 

Tiny particles, smaller than one thousandth the width of a human hair, trapped within the metal have retained the magnetic signature of the parent asteroid from its birth in the early Solar System.

"We're taking ancient magnetic field measurements in nano-scale materials to the highest ever resolution in order to piece together the magnetic history of asteroids - it's like a cosmic archaeological mission," said Dr James Bryson, the paper's lead author. 

"Since asteroids are much smaller than Earth, they cooled much more quickly, so these processes occur on a shorter timescales, enabling us to study the whole process of core solidification."

Prof Wyn William, from the University of Edinburgh, who was not involved in the study, commented: "To be able to get a time stamp on these recordings, to get a cooling rate and the time of solidification, is fantastic. It's a very nice piece of work."

The key to the long-lived stability of the recording is the atomic-scale structure of the iron-nickel particles that grew slowly in the asteroid core and survived in the meteorites. 

Making a final comment on the results, Dr Harrison said: "In our meteorites we've been able to capture both the beginning and end of core freezing, which will help us understand how these processes affected the Earth in the past and provide a possible glimpse of what might happen in the future." 

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Get ready! NASA spacecraft soon to rendezvous with dwarf planet Ceres

January 1, 2015 / / 0 Comments




Excerpt from latimes.com

After voyaging 2.4 billion miles through space, NASA’s Dawn spacecraft is finally in the home stretch of its journey to Ceres, the largest member of the asteroid belt and one of five dwarf planets in the solar system.
Dawn was launched in 2007 to study two very different asteroids and learn more about the building blocks of our solar system. Ceres is Dawn’s second stop; its first was Vesta, which the spacecraft circled from July 2011 to September 2012.

Now, after leaving Vesta and traveling through space for more than two years, the spacecraft is roughly 400,000 miles away from Ceres and speeding toward it at about 450 mph, with a rendezvous set for March 6.
Ceres is a dwarf planet, along with Haumea, Makemake, Pluto and Eris (whose discovery led to Pluto’s infamous planetary demotion). At 590 miles across and holding roughly a third of the mass of the asteroid belt, Ceres is large enough that its own gravity pulls it into a spherical shape – which is part of why it was once considered to be very planet-like. In fact, Ceres was listed as a planet for decades after its discovery in 1801, and was briefly reconsidered during the 2006 debate surrounding Pluto’s planetary status.
Ceres is the only dwarf planet in the inner solar system. Although it’s much larger than Vesta, it’s more of a mystery. Scientists have meteorites that they believe are from Vesta, which they can study and compare to Dawn’s observations of the asteroid; but no such fragments found on Earth have been linked to Ceres. Until now, fuzzy images taken by NASA’s Hubble Space Telescope have provided our best view of the icy dwarf planet. But that should change by the end of January, as Dawn approaches its target.


Why are these two "protoplanets" so different? Scientists think Vesta formed earlier, when radioactive material was more abundant and produced more heat, leaving the asteroid very dry. Ceres may have formed later. Some researchers also think that Ceres may have originated much farther out in the solar system, before being yanked into its current position during a dramatic upheaval earlier in the solar system’s development.

As building blocks of our solar system that never became full planets, these protoplanets’ divergent life stories could shed light on the early solar system’s history.


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Did drought doom the Mayan Empire? New evidence from Belize’s ‘Blue Hole’

December 30, 2014 / / 0 Comments




Minerals taken from lagoons reveal a century-long drought occurred between A.D. 800 and A.D. 900, right when the Mayan civilization disintegrated.

Excerpt from Livescience.com

By Tia Ghose  


Drought may have driven the ancient Mayan Empire to collapse, new research suggests.

Minerals taken from Belize's famous underwater cave, known as the Blue Hole, as well as lagoons nearby, show that an extreme, century-long drought occurred between A.D. 800 and A.D. 900, right when the Mayan civilization disintegrated. After the rains returned, the Mayans moved north — but they disappeared again a few centuries later, and that disappearance occurred at the same time as another dry spell, the sediments reveal. 

Rise and decline

From A.D. 300 to A.D. 700, the Mayan civilization flourished in the Yucatan peninsula. These ancient Mesoamericans built stunning pyramids, mastered astronomy, and developed both a hieroglyphic writing system and a calendar system, which is famous for allegedly predicting that the world would end in 2012.


But in the centuries after A.D. 700, the civilization's building activities slowed and the culture descended into warfare and anarchy. Historians have speculatively linked that decline with everything from the ancient society's fear of malevolent spirits to deforestation completed to make way for cropland to the loss of favored foods, such as the Tikal deer.

The evidence for a drought has been growing in recent years: Since at least 1995, scientists have been looking more closely at the effects of drought. A 2012 study in the journal Science analyzed a 2,000-year-old stalagmite from a cave in southern Belize and found that sharp decreases in rainfall coincided with periods of decline in the culture. But that data came from just one cave, which meant it was difficult to make predictions for the area as a whole, Droxler said.

The main driver of this drought is thought to have been a shift in the intertropical convergence zone (ITCZ), a weather system that generally dumps water on tropical regions of the world while drying out the subtropics. During summers, the ITCZ pelts the Yucatan peninsula with rain, but the system travels farther south in the winter. Many scientists have suggested that during the Mayan decline, this monsoon system may have missed the Yucatan peninsula altogether.

Deep history

The team found that during the period between A.D. 800 and A.D. 1000, when the Mayan civilization collapsed, there were just one or two tropical cyclones every two decades, as opposed to the usual five or six. After that, the Maya moved north, building at sites such as Chichen Itza, in what is now Mexico.

But the new results also found that between A.D. 1000 and A.D. 1100, during the height of the Little Ice Age, another major drought struck. This period coincides with the fall of Chichen Itza.

The findings strengthen the case that drought helped usher in the long decline of the Mayan culture.


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Top 10 Ridiculously Common Science Myths

November 30, 2014 / / 0 Comments






listverse.com
There is nothing better than a bit of mythbusting (which accounts for the popularity of the television program of the same name), so here we are again, presenting you with a new list of terribly common misconceptions and myths – this time about science.

10
Evolutionary Improvements
Evolution Std.Jpg
The Myth: Evolution causes something to go from “lower” to “higher”
While it is a fact that natural selection weeds out unhealthy genes from the gene pool, there are many cases where an imperfect organism has survived. Some examples of this are fungi, sharks, crayfish, and mosses – these have all remained essentially the same over a great period of time. These organisms are all sufficiently adapted to their environment to survive without improvement.
Other taxa have changed a lot, but not necessarily for the better. Some creatures have had their environments changed and their adaptations may not be as well suited to their new situation. Fitness is linked to their environment, not to progress.

9
Humans Pop In Space
Ed-White.Jpg
The Myth: When exposed to the vacuum of space, the human body pops
This myth is the result of science fiction movies which use it to add excitement or drama to the plot. In fact, a human can survive for 15 – 30 seconds in outer space as long as they breathe out before the exposure (this prevents the lungs from bursting and sending air into the bloodstream). After 15 or so seconds, the lack of oxygen causes unconsciousness which eventually leads to death by asphyxiation.
8
Brightest Star
800Px-Sirius A And B Artwork.Jpg
The Myth: Polaris is the brightest star in the northern hemisphere night sky
Sirius is actually brighter with a magnitude of ?1.47 compared to Polaris’ 1.97 (the lower the number the brighter the star). The importance of Polaris is that its position in the sky marks North – and for that reason it is also called the “North Star”. Polaris is the brightest star in the constellation Ursa Minor and, interestingly, is only the current North Star as pole stars change over time because stars exhibit a slow continuous drift with respect to the Earth’s axis.
7
Five Second Rule
5Seconds1.Jpg
The Myth: Food that drops on the floor is safe to eat if you pick it up within five seconds
This is utter bunkum which should be obvious to most readers. If there are germs on the floor and the food lands on them, they will immediately stick to the food. Having said that, eating germs and dirt is not always a bad thing as it helps us to develop a robust immune system. I prefer to have a “how-tasty-is-it” rule: if it is something really tasty, it can sit there for ten minutes for all I care – I will still eat it.
6
Dark side of the Moon
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The Myth: There is a dark side of the moon
Actually – every part of the moon is illuminated at sometime by the sun. This misconception has come about because there is a side of the moon which is never visible to the earth. This is due to tidal locking; this is due to the fact that Earth’s gravitational pull on the moon is so immense that it can only show one face to us. Wikipedia puts it rather smartly thus: “Tidal locking occurs when the gravitational gradient makes one side of an astronomical body always face another; for example, one side of the Earth’s Moon always faces the Earth. A tidally locked body takes just as long to rotate around its own axis as it does to revolve around its partner. This synchronous rotation causes one hemisphere constantly to face the partner body.”


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Brain Cells
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The Myth: Brain cells can’t regenerate – if you kill a brain cell, it is never replaced
The reason for this myth being so common is that it was believed and taught by the science community for a very long time. But in 1998, scientists at the Sweden and the Salk Institute in La Jolla, California discovered that brain cells in mature humans can regenerate. It had previously been long believed that complex brains would be severely disrupted by new cell growth, but the study found that the memory and learning center of the brain can create new cells – giving hope for an eventual cure for illnesses like Alzheimer’s.
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Pennies from Heaven
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The Myth: A penny dropped from a very high building can kill a pedestrian below
This myth is so common it has even become a bit of a cliche in movies. The idea is that if you drop a penny from the top of a tall building (such as the Empire State Building) – it will pick up enough speed to kill a person if it lands on them on the ground. But the fact is, the aerodynamics of a penny are not sufficient to make it dangerous. What would happen in reality is that the person who gets hit would feel a sting – but they would certainly survive the impact.
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Friction Heat
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The Myth: Meteors are heated by friction when entering the atmosphere
When a meteoroid enters the atmosphere of the earth (becoming a meteor), it is actually the speed compressing the air in front of the object that causes it to heat up. It is the pressure on the air that generates a heat intense enough to make the rock so hot that is glows brilliantly for our viewing pleasure (if we are lucky enough to be looking in the sky at the right time). We should also dispel the myth about meteors being hot when they hit the earth – becoming meteorites. Meteorites are almost always cold when they hit – and in fact they are often found covered in frost. This is because they are so cold from their journey through space that the entry heat is not sufficient to do more than burn off the outer layers.
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Lightning
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The Myth: Lightning never strikes the same place twice
Next time you see lightning strike and you consider running to the spot to protect yourself from the next bolt, remember this item! Lightning does strike the same place twice – in fact it is very common. Lightning obviously favors certain areas such as high trees or buildings. In a large field, the tallest object is likely to be struck multiple times until the lightning moves sufficiently far away to find a new target. The Empire State Building gets struck around 25 times a year.
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Gravity in Space
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The Myth: There is no gravity in space
In fact, there is gravity in space – a lot of it. The reason that astronauts appear to be weightless because they are orbiting the earth. They are falling towards the earth but moving sufficiently sideways to miss it. So they are basically always falling but never landing. Gravity exists in virtually all areas of space. When a shuttle reaches orbit height (around 250 miles above the earth), gravity is reduced by only 10%.
Inspired by an excellent LiveScience Article. This article is licensed under the GFDL because it contains quotations from Wikipedia.

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Antikythera Mechanism ~ World’s oldest computer is more ancient than first thought

November 28, 2014 / / 0 Comments

Excerpt from dailymail.co.ukThis is according to Argentinian scientists who found eclipse calendarThe calender included a solar eclipse that happened on May 12, 205 BC Previous radiocarbon dating analysis of had dates mechanism to 100 BCThe study&...

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Earth ‘has Star Trek force fields’

November 26, 2014 / / 0 Comments

Excerpt frombelfasttelegraph.co.ukA US team discovered the barrier, some 7,200 miles above the Earth's surface, that blocks high energy electrons threatening astronauts and satellites.Scientists identified an "extremely sharp" boundary within the Van...

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