Science & TechnologyS


Telescope

Best of the Web: The Sky Is Falling

Gregg Easterbrook
The Atlantic
Wed, 14 May 2008 13:51 UTC
The odds that a potentially devastating space rock will hit Earth this century may be as high as one in 10. So why isn't NASA trying harder to prevent catastrophe?

Comet
©Stéphane Guisard, www.astrosurf.com/sguisard

Breakthrough ideas have a way of seeming obvious in retro­spect, and about a decade ago, a Columbia University geophysicist named Dallas Abbott had a breakthrough idea. She had been pondering the craters left by comets and asteroids that smashed into Earth. Geologists had counted them and concluded that space strikes are rare events and had occurred mainly during the era of primordial mists. But, Abbott realized, this deduction was based on the number of craters found on land - and because 70 percent of Earth's surface is water, wouldn't most space objects hit the sea? So she began searching for underwater craters caused by impacts rather than by other forces, such as volcanoes. What she has found is spine-chilling: evidence that several enormous asteroids or comets have slammed into our planet quite recently, in geologic terms. If Abbott is right, then you may be here today, reading this magazine, only because by sheer chance those objects struck the ocean rather than land.
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Bulb

Acid rain traces support meteor theory for 1908 Tunguska blast


RIA Novosti
Mon, 30 Jun 2008 14:35 UTC
International researchers investigating the Tunguska Event, an explosion exactly 100 years ago in central Siberia, say acid rain traces in the region back up the theory that the blast was caused by a meteorite.

On June 30, 1908, an explosion equivalent to between 5 and 30 megatons of TNT occurred approximately 7-10 km (3-6 miles) above the Podkamennaya Tunguska River in a remote Siberian region.

"Extremely high temperatures occurred as the meteorite entered the atmosphere, during which the oxygen in the atmosphere reacted with nitrogen causing a build up of nitrogen oxides," one of the authors of the joint research, Natalia Kolesnikova, told RIA Novosti.

Kolesnikova said a similar impact 66 million years ago wiped out a significant portion of life on Earth, including the dinosaurs.
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Meteor

Fire in the sky: Tunguska at 100

Paul Rincon
BBC
Mon, 30 Jun 2008 13:26 UTC


Image
©Unknown
The Tunguska event was caused by a space rock tens of metres across

At 7:17am on 30 June 1908, an immense explosion tore through the forest of central Siberia.

Some 80 million trees were flattened over an area of 2,000 square km (800 square miles) near the Tunguska River.

The blast was 1,000 times more powerful than the atomic bombs dropped on Hiroshima and Nagasaki and generated a shock wave that knocked people to the ground 60km from the epicentre.

The cause was an asteroid or comet just a few tens of metres across which detonated 5-10km above the ground, 100 years ago today.

Eyewitnesses recalled a brilliant fireball resembling a "flying star" ploughing across the cloudless June sky at an oblique angle.
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Meteor

Crater study surprise: Deep in ground where meteorite hit, rocks are full of extra-salty water

Dennis O'Brien
Baltimore Sun
Fri, 27 Jun 2008 12:55 UTC


Image
©Handout out photo by Science
An artist's conception of the mile-wide meteorite crashing into Earth 35 million years ago in the Chesapeake Bay.

Scientists drilling into the site where a giant meteorite smashed into the lower Chesapeake Bay millions of years ago have found one more surprise amid the microscopic life and pockets of prehistoric ocean.

The water is saltier than expected - and no one is sure why.

"It's not a reservoir. It's water in pores and in cracks and shattered rocks," said Ward Sanford, a hydrologist with the U.S. Geological Survey.

Scientists have been examining the bay impact crater since its discovery in 1993.
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Meteor

Tunguska Event: No answers to fireball mystery

David Hill
Otago Daily Times
Sat, 28 Jun 2008 12:12 UTC


Image
©Unknown
When Russian mineralogist Leonid Kulik made his way to the remote Tunguska River basin, his group found thousands of pine trees lying burned in a radial pattern.

JUNE 30, 1908.

Reindeer graze beside the Podkamennaya or Lower Stony Tunguska River that winds through the Siberian steppes.

The tents of a few herdsmen stand nearby, but hardly anyone else lives in this land of swamps and forests.

7.14 am. Pine trees glow in the summer light. The morning is blue and cloudless.

Then a blinding ball of light rips across the sky, trailing a column of fire.

Some eye-witnesses say the light was red. Others claim it was blue, and cylindrical in shape.

It races down towards the Tunguska River, and explodes.

A spear of fire splits the sky. Explosions boom across the land.

A dark mushroom cloud begins rolling upwards. It will reach a height of 80km: ten times higher than Mt Everest.
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Question

Flashback Fossil DNA tells tales of red-haired Neanderthals

Robert C. Cowen
The Christian Science Monitor
Thu, 08 Nov 2007 16:20 UTC
Paleontologists are surprised to find such diversity; clues also suggest wider migration.

Red headed Neanderthals
©Michael Hofreiter and Kurt Fiust
Some Neanderthals may have had pale skin and red hair similar to that of some modern humans.

Scientists probing Neanderthal remains find important clues in DNA. One recent study suggests some of our extinct cousins had pale skin and red hair. Another investigation finds Neanderthals ranged much farther from Europe into Asia than paleontologists have thought.

The key fact is that at least some Neanderthal fossils yield DNA of high enough quality to tell such tales. Last month, members of an international research team led by Carles Lalueza-Fox at the University of Barcelona in Spain explained in the journal Nature why they think recovering specific DNA sequences from extinct species "can potentially provide information" as to what the species looked like. They backed up this hypothesis with analysis of DNA from two Neanderthal fossils.

They found genetic information similar to, but distinct from, the genes governing skin and hair color in modern humans. They say this "suggests that Neanderthals varied in pigmentation levels" just as we do. That includes the pale skin and red hair that evolved largely in Europe. The team adds that the data suggest this potential "evolved independently in both modern humans and Neanderthals."

Comment: For more articles on this subject see: Red hair a part of of Neanderthal genetic profile, Red hair a legacy of Neanderthal man, Neanderthals 'were flame-haired', Ancient DNA Reveals That Some Neanderthals Were Redheads, and Some Neanderthals were redheads - Bones yield genetic data that adds red hair, light skin and maybe freckles.

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Rocket

As research funds stagnate, science in state of 'crisis'

Amy Ellis Nutt
Star-Ledger
Sun, 29 Jun 2008 01:58 UTC
Once the world's gold standard, American scientific enterprise is in free fall. Short of government funds and strapped for cash, researchers across the country are abandoning promising avenues of scientific investigation and, increasingly, the profession of science itself.
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Bug

Lyme Disease Bacterium Came From Europe Before Ice Age


Science Daily
Sun, 29 Jun 2008 22:13 UTC
Researchers at the University of Bath have discovered that a bacterium that causes Lyme disease originated in Europe, rather than in North America as previously thought.

blacklegged tick
©CDC/ James Gathany; William Nicholson
The blacklegged tick Ixodes pacificus, a known vector for Borrelia burgdorferi, the pathogen responsible for Lyme disease.

The bacterium responsible for Lyme disease, Borrelia burgdorferi, originated in America, or so researchers thought. Now, however, a team from the University of Bath has shown that this bug in fact came from Europe, originating from before the Ice Age.

By understanding the origins of the bacterium and how it has evolved so far researchers hope to be able to predict how it will continue to develop, and so find ways to prevent its spread.
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Evil Rays

Cluster Listens To The Sounds Of Earth


Agence France-Presse
Sun, 29 Jun 2008 21:43 UTC
The first thing an alien race is likely to hear from Earth is chirps and whistles, a bit like R2-D2, the robot from Star Wars. In reality, they are the sounds that accompany the aurora.

Now ESA's Cluster mission is showing scientists how to understand this emission and, in the future, search for alien worlds by listening for their sounds.

Cluster constellation
©ESA
Artist's impression of the Cluster constellation. ESA's mission Cluster consists of four identical spacecraft flying in formation between 19000 and 119000 km above the Earth. They study the interaction between the solar wind and Earth's magnetosphere, or the Sun-Earth connection in 3D.

Scientists call this radio emission the Auroral Kilometric Radiation (AKR). It is generated high above the Earth, by the same shaft of solar particles that then causes an aurora to light the sky beneath.

For decades, astronomers had assumed that these radio waves travelled out into space in an ever-widening cone, rather like light emitted from a torch. Thanks to Cluster, astronomers now know this is not true.

By analysing 12 000 separate bursts of AKR, a team of astronomers have determined that the AKR is beamed into space in a narrow plane. This is like placing a mask over the torch with just a small slit in the middle for light to escape.

"We can now determine exactly where the emission is coming from," says Robert Mutel, University of Iowa, who conducted the three-year study with colleagues. For each of the AKR bursts they analysed, the astronomers pinpointed its point of origin to regions in Earth's magnetic field just a few tens of kilometres in size. These were located a few thousand kilometres above where the light of the aurora is formed.
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Telescope

A Quark Star? Super-luminous Stellar Explosion Observed


Science Daily
Sun, 29 Jun 2008 15:38 UTC
Astronomers recently announced that they have found a novel explanation for a rare type of super-luminous stellar explosion that may have produced a new type of object known as a quark star.

Three exceptionally luminous supernovae explosions have been observed in recent years. One of them was first observed using a robotic telescope at the California Institute of Technology's (Caltech) Palomar Observatory.

supernova explosion
©NASA/CXC/M.Weiss
Illustration of a supernova explosion.

Data collected with Palomar's Samuel Oschin Telescope was transmitted from the remote mountain site in southern California to astronomers via the High-Performance Wireless Research and Education Network (HPWREN), funded by the National Science Foundation (NSF). The Nearby Supernova Factory research group at the Lawrence Berkeley Laboratory reported the co-discovery of the supernova, known as SN2005gj.

Researchers in Canada have analyzed this, along with two other supernovae, and believe that they each may be the signature of the explosive conversion of a neutron star into a quark star.
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