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Fabled past awaits in Sudan desert

Guillaume Lavallee
Agence France-Presse
Sun, 07 Mar 2010 13:48 UTC
There is not a tourist in sight as the sun sets over sand-swept pyramids at Meroe, but archaeologists say the Nubian Desert of northern Sudan holds mysteries to rival Egypt.

"There is a magic beauty about these sites that is heightened by the privilege of being able to admire them alone, with the pyramids, the dunes and the sun," Guillemette Andreu, head of antiquities at the Louvre museum in Paris, says. "It really sets them apart from the Egyptian pyramids, whose beauty is slightly overshadowed by the tourist crowds."

Meroe lies about 200 kilometres northeast of Sudan's capital Khartoum and was the last capital of Kush, also called Nubia, an ancient kingdom centred on the confluence of the Blue Nile, the White Nile and the Atbara River.

Kush was one of the earliest civilisations in the Nile valley and, at first, Egypt dominated it. The Nubians gained their independence and, at the height of their power, they turned the table on Egypt and conquered it in the 8th century BC. They occupied the entire Nile valley for a century before being forced back into what is now Sudan.
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Radar

Shields down! Earth's magnetic field may drop in a flash


New Scientist
Thu, 04 Mar 2010 17:33 UTC
Image
© NASA/SPLThere'll be little warning if Earth's magnetic field flips
Even if we knew precise details of Earth's core, we would not be able to predict a catastrophic flip in the polarity of its magnetic field more than a decade or two ahead.

Our planet's magnetic field has reversed polarity from time to time throughout its history. Some models suggest that a flip would be completed in a year or two, but if, as others predict, it lasted decades or longer we would be left exposed to space radiation. This could short-circuit satellites, pose a risk to aircraft passengers and play havoc with electrical equipment on the ground.

To test whether we would see a flip coming, Gauthier Hulot of Denis Diderot University in Paris, France, and colleagues ran computer simulations of Earth's magnetic dynamo based on a range of plausible values for inputs such as the viscosity, electrical and thermal conductivity of the outer core, and the temperature difference across it. The model's predictions remained consistent over this range of values for no more than a few decades, Hulot's team will report in Geophysical Research Letters. Their result implies that we can forecast a flip only this far in advance - and then only with data that is as precise as possible. "It's like predicting the weather," says Hulot.
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Blackbox

Universe's high-energy haze gets murkier

Rachel Courtland
New Scientist
Sat, 06 Mar 2010 17:25 UTC
Image
© NASA/DOE/Fermi LAT CollaborationThe source of most of the fog of gamma-ray light beyond the Milky Way is unknown
The universe's most powerful particle accelerators are responsible for just a fraction of the fog of gamma-ray light beyond the Milky Way, a new study suggests. The source of the rest remains a mystery, but dark matter could be a contributor.

The gamma-ray sky is dominated by the glow of our Milky Way as well as other known galaxies and individual neutron stars. But the universe is also aglow with a diffuse haze of gamma-ray light, produced by sources that may be too distant, dim, or diffuse to resolve individually.

By convention, astrophysicists have long assumed that most - if not all - of this gamma-ray fog gets its start inside galaxies whose supermassive black holes are spewing jets of charged particles into space as they feed on surrounding matter.

But a new analysis of data collected by NASA's Fermi telescope suggests these so-called active galactic nuclei (AGN) account for no more than 30 per cent of the universe's gamma-ray glow.

"Most of it - 70 per cent of the background - is unexplained at the moment," says study leader Marco Ajello of the Kavli Institute for Particle Astrophysics and Cosmology in Stanford, California. Ajello spoke with reporters on Tuesday at a meeting of the High Energy Astrophysics Division of the American Astronomical Society in Waikoloa, Hawaii.
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Satellite

NASA turned on by blow-up space stations

Paul Marks
New Scientist
Wed, 03 Mar 2010 17:12 UTC
NASA is planning to investigate making inflatable space-station modules to make roomier, lighter, cheaper-to-launch spacecraft, it reveals in its budget proposal released on 22 February. We look into the technologies involved.

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Meteor

Dark, Dangerous Asteroids found Lurking near Earth

David Shiga
New Scientist
Fri, 05 Mar 2010 13:49 UTC
Asteroid
© NASA/JPL-Caltech/UCLANow you see it: a near-Earth object becomes visible in infrared.
An infrared space telescope has spotted several very dark asteroids that have been lurking unseen near Earth's orbit. Their obscurity and tilted orbits have kept them hidden from surveys designed to detect things that might hit our planet.

Called the Wide-Field Infrared Survey Explorer (WISE), the new NASA telescope launched on 14 December on a mission to map the entire sky at infrared wavelengths. It began its survey in mid-January.

In its first six weeks of observations, it has discovered 16 previously unknown asteroids with orbits close to Earth's. Of these, 55 per cent reflect less than one-tenth of the sunlight that falls on them, which makes them difficult to spot with visible-light telescopes. One of these objects is as dark as fresh asphalt, reflecting less than 5 per cent of the light it receives.

Many of these dark asteroids have orbits that are steeply tilted relative to the plane in which all the planets and most asteroids orbit. This means telescopes surveying for asteroids may be missing many other objects with tilted orbits, because they spend most of their time looking in this plane.

Fortunately, the new objects are bright in infrared radiation, because they absorb a lot of sunlight and heat up. This makes them relatively easy for WISE to spot.
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Magnify

John Hopkins Research: Over a Decade of DNA Evidence May be Faulty

Jason Mick
Daily Tech
Thu, 04 Mar 2010 15:31 UTC
Image
A close up view shows a 3D animation of a mitochondria, a tiny symbiotic helper that lives inside human cells. DNA from mitochondria has been used since the mid 1990s in certain criminal cases.
Findings could lead to appeals nationwide, if verified

"You've got the wrong man! I'm innocent!"

Many perfectly guilty criminals insist that, but what if it was true? That indeed could be true in some cases, as a new revelation casts doubt on certain verdicts in the U.S. Justice system delivered since the mid-1990s. It stems from an important finding made by a team co-led by Nickolas Papadopoulos, a Johns Hopkins University geneticist. The team discovered that DNA from tiny symbiotic bacterial-descendants called mitochondria that live in our cells and give them energy varies from tissue to tissue in the human body.

The finding is significant as mitochondrial DNA analysis was considered a proven enough technique that U.S. law enforcement has been using it as a tool to identify criminals since the mid-1990s. Mitochondrial DNA analysis was often used in the cases where the human DNA was too damaged for accurate processing (there's numerous mitochondria in a cell, so there's a better chance of accurately processing it).
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Magnify

Geophysicists Push Age of Earth's Magnetic Field Back 250 Million Years

Lisa Grossman
Science News
Thu, 04 Mar 2010 12:00 UTC
Image
© NASAEarth’s magnetic field protects life at the planet’s surface by holding the solar wind at bay, as shown in this artist’s illustration. New research suggests the magnetic field existed 3.45 billion years ago but was 30 to 50 percent weaker than it is today.
Planetary shield formed soon enough to protect early life forms from harmful solar radiation

Earth's magnetic field existed about 250 million years earlier than previously thought, new research suggests, which would make it old enough to have shielded life on the planet's surface from the sun's most harmful cosmic radiation.

Earth's magnetic field was born 3.45 billion years ago, a team including researchers from the University of Rochester in New York and the University of KwaZulu-Natal in South Africa report in the March 5 issue of Science.

That formation date falls during life's earliest stages of development, between the period when the Earth was pummeled by interplanetary debris and when the atmosphere filled with oxygen. Several earlier studies had suggested that a magnetic field is a necessary shield against deadly solar radiation that can strip away a planet's atmosphere, evaporate water and snuff out life on its surface.
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Meteor

New study blames dinosaur deaths on big meteor strike


DPA
Thu, 04 Mar 2010 19:02 UTC
Nuremberg, Germany - A new German-led study has marshalled even more powerful evidence that a single meteor strike 65 million years ago led to the sudden extinction of all the earth's dinosaurs. That theory has dominated dinosaur studies for a couple of decades, but has remained unproven, with some dissidents saying a monstrous volcanic eruption in India caused the extinction.

Peter Schulte of the University of Erlangen and Nuremberg said evidence turned up by scientists in recent years indicated the impact on what is now the Yucatan peninsula of Mexico was the cause.

The review by 41 scientists was published Thursday in the journal Science.
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Meteor

Asteroid Killed Off the Dinosaurs, Says International Scientific Panel


Science Daily
Thu, 04 Mar 2010 21:37 UTC
Impact
© Don Davis/NASAAn artist's rendering of the moment of impact when an enormous space rock struck the Yucatán peninsula at the end of the Cretaceous Period.
The Cretaceous-Tertiary mass extinction, which wiped out the dinosaurs and more than half of species on Earth, was caused by an asteroid colliding with Earth and not massive volcanic activity, according to a comprehensive review of all the available evidence, published in the journal Science.

A panel of 41 international experts, including UK researchers from Imperial College London, the University of Cambridge, University College London and the Open University, reviewed 20 years' worth of research to determine the cause of the Cretaceous-Tertiary (KT) extinction, which happened around 65 million years ago. The extinction wiped out more than half of all species on the planet, including the dinosaurs, bird-like pterosaurs and large marine reptiles, clearing the way for mammals to become the dominant species on Earth.

The new review of the evidence shows that the extinction was caused by a massive asteroid slamming into Earth at Chicxulub (pronounced chick-shoo-loob) in Mexico. The asteroid, which was around 15 kilometres wide, is believed to have hit Earth with a force one billion times more powerful than the atomic bomb at Hiroshima. It would have blasted material at high velocity into the atmosphere, triggering a chain of events that caused a global winter, wiping out much of life on Earth in a matter of days.
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Telescope

Biggest, Deepest Crater Exposes Hidden, Ancient Moon

Bill Steigerwald
NASA Goddard Space Flight Center
Thu, 04 Mar 2010 20:44 UTC
Image
© Japan Aerospace Exploration Agency/NASA Image 1: This is elevation map covering the eastern portion of South Pole-Aitken basin, including the Apollo Basin, made using data from Japan’s Kaguya spacecraft. The false colors indicate height; red represents highlands, and blue represents the lowest areas. Dashed circles mark the location of the main and inner ring of Apollo. The dashed line marks the location of the topographic profile illustrated in the Image 2 below.
Shortly after the Moon formed, an asteroid smacked into its southern hemisphere and gouged out a truly enormous crater, the South Pole-Aitken basin, almost 1,500 miles across and more than five miles deep.

"This is the biggest, deepest crater on the Moon -- an abyss that could engulf the United States from the East Coast through Texas," said Noah Petro of NASA's Goddard Space Flight Center in Greenbelt, Md. The impact punched into the layers of the lunar crust, scattering that material across the Moon and into space. The tremendous heat of the impact also melted part of the floor of the crater, turning it into a sea of molten rock.
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