Science & TechnologyS


Info

Earth's Magnetic Field Reversals Illuminated By Lava Flows Study


Science Daily
Fri, 26 Sep 2008 13:25 UTC
Earth's north magnetic pole is shifting and weakening. Ancient lava flows are guiding a better understanding of what generates and controls the Earth's magnetic field - and what may drive it to occasionally reverse direction.

Image
©iStockphoto/Tobias Machhaus
Polarity reversals have occurred hundreds of times at irregular intervals throughout the planet's history - most recently about 780,000 years ago - but scientists are still trying to understand how and why.

The main magnetic field, generated by turbulent currents within the deep mass of molten iron of the Earth's outer core, periodically flips its direction, such that a compass needle would point south rather than north. Such polarity reversals have occurred hundreds of times at irregular intervals throughout the planet's history - most recently about 780,000 years ago - but scientists are still trying to understand how and why.

A new study of ancient volcanic rocks, reported in the Sept. 26 issue of the journal Science, shows that a second magnetic field source may help determine how and whether the main field reverses direction. This second field, which may originate in the shallow core just below the rocky mantle layer of the Earth, becomes important when the main north-south field weakens, as it does prior to reversing, says Brad Singer, a geology professor at the University of Wisconsin-Madison.
Read More...
Sherlock

Puzzling Property Of Night-shining Clouds At Edge Of Space Explained


Science Daily
Fri, 26 Sep 2008 12:57 UTC
An explanation for a strange property of noctilucent clouds--thin, wispy clouds hovering at the edge of space at 85 km altitude--has been proposed by an experimental plasma physicist at the California Institute of Technology (Caltech), possibly laying to rest a decades-long mystery.

Noctilucent Cloud
©NASA
Noctilucent Cloud

Noctilucent clouds, also known as night-shining clouds, were first described in 1885, two years after the massive eruption of Krakatoa, a volcanic island in Indonesia, sent up a plume of ash and debris up to 80 km into Earth's atmosphere. The eruption affected global climate and weather for years and may have produced the first noctilucent clouds.

The effects of Krakatoa eventually faded, but the unusual electric blue clouds remain, nestled into a thin layer of Earth's mesosphere, the upper atmosphere region where pressure is 10,000 times less than at sea level. The clouds, which are visible during the deep twilight, are most often observed during the summer months at latitudes from 50 to 70 degrees north and south--although in recent years they have been seen as far south as Utah and Colorado. Noctilucent clouds are a summertime phenomenon because, curiously, the atmosphere at 85 km altitude is coldest in summer, promoting the formation of the ice grains that make up the clouds.
Read More...
Info

Oldest Known Rocks On Earth Discovered: 4.28 Billion Years Old


Science Daily
Fri, 26 Sep 2008 12:47 UTC
The discovery of rocks as old as 4.28 billion years pushes back age of most ancient remnant of Earth's crust by 300 million years.

Image
©Don Francis
These rocks, known as "faux-amphibolites", may be remnants of a portion of Earth's primordial crust -- the first crust that formed at the surface of our planet.

McGill University researchers have discovered the oldest rocks on Earth - a discovery which sheds more light on our planet's mysterious beginnings. These rocks, known as "faux-amphibolites", may be remnants of a portion of Earth's primordial crust - the first crust that formed at the surface of our planet.

The ancient rocks were found in Northern Quebec, along the Hudson's Bay coast, 40 km south of Inukjuak in an area known as the Nuvvuagittuq greenstone belt.

The discovery was made by Jonathan O'Neil, a Ph.D. candidate at McGill's Department of Earth and Planetary Sciences, Richard W. Carlson, a researcher at the Carnegie Institution for Science in Washington, D.C., Don Francis, a McGill professor in the Department of Earth and Planetary Sciences, and Ross K. Stevenson, a professor at the Université du Québec à Montréal (UQAM).
Read More...
Bulb

MIT solves 100-year-old engineering problem

Elizabeth A. Thomson
MIT
Thu, 25 Sep 2008 22:32 UTC
As a car accelerates up and down a hill then slows to follow a hairpin turn, the airflow around it cannot keep up and detaches from the vehicle. This aerodynamic separation creates additional drag that slows the car and forces the engine to work harder. The same phenomenon affects airplanes, boats, submarines, and even your golf ball.

Now, in work that could lead to ways of controlling the effect with potential impacts on fuel efficiency and more, MIT scientists and colleagues have reported new mathematical and experimental work for predicting where that aerodynamic separation will occur.
Read More...
Bulb

Metal-fungus hybrids make for more powerful catalysts

Colin Barras
New Scientist
Wed, 24 Sep 2008 22:20 UTC
It brings a new meaning to the phrase organic chemistry. Chemists have discovered that fungi can naturally absorb microscopic metal particles into their flesh in a way that could see metallic fungus used as catalysts or disinfectants.

Industrial catalysts often rely on processes that happen on the surface of metals, so tiny nanoparticles of catalyst with large surface-area-to-volume ratios are particularly effective. But such particles are only effective if they are prevented from clumping together using a chemical solution, which makes it difficult to separate the catalyst from the products of a reaction.
Read More...
Better Earth

Our Ocean Backyard: Drilling reveals drama: Asteroid collisions, mass extinction and the loss of an entire sea

Gary Griggs
The Mercury News
Sun, 14 Sep 2008 18:15 UTC
What began as a farfetched idea 50 years ago, drilling a hole into the sea floor from a floating vessel, was successful and soon opened up an exciting new era of ocean exploration which continues today.

The Ocean Drilling Program, by obtaining long cores of sediment and ancient rock from the floors of the world's oceans, has been making discoveries that have challenged old ideas and brought entirely new concepts to light. Drill ships have evolved and become more sophisticated, enabling scientists to drill in greater water depths and progressively deeper into the sea floor.

Hundreds of cores have been obtained over the past four decades, in water more than 4 miles deep and penetrating as deep as 6,000 feet into the ocean floor. Each voyage is normally two months long and typically involves dozens of scientists from universities around the world. The United States has provided much of the scientific leadership over the years, and scientists at UC Santa Cruz have played major roles in organizing and leading the scientific drilling program.

What have we discovered as these voyages have continued to probe the deep ocean floor? Drilling in the Caribbean uncovered proof that an asteroid struck near the Yucatan peninsula 65 million years ago, and not only led to the extinction of 60 to 70 percent of all plant and animals species on earth, including 90 percent of all of the plankton in the ocean, but also led to the die-out of the dinosaurs.
Read More...
Telescope

Mercury's Spider Pantheon Fossae Formation Linked To Asteroid Impact


Space Daily
Wed, 24 Sep 2008 18:05 UTC


Image
©SpaceDaily.com
The Caloris Basin is the youngest-known large impact basin on Mercury.

As NASA's MESSENGER spacecraft prepares for its second flyby of Mercury, new analyses of data from the first flyby will be presented at the European Planetary Science Congress in Munster on Tuesday 23rd September

Dr Sean Solomon, MESSENGER's Principal Investigator, will present a model that suggests that the origin of the Pantheon Fossae, a radiating web of troughs located in the giant Caloris Basin, is directly linked to an impact crater at the centre of the web.
Read More...
Meteor

UC Berkeley Expert and Association of Space Explorers Study Global Strategy to Defend Against Incoming Asteroids


NewsWire
Tue, 23 Sep 2008 18:01 UTC
San Francisco, CA -- Professor Karlene Roberts has never donned a spacesuit nor orbited around the planet, but the spirited organizational behavior expert at UC Berkeley's Haas School of Business was tapped to help a committee of astronauts, diplomats, and legal experts find ways to mitigate the impact of an asteroid hitting Earth.

Read More...
Telescope

Hubble Spies Galaxy Silhouettes


Science Daily
Thu, 25 Sep 2008 13:37 UTC
NASA's Hubble Space Telescope has captured a rare alignment between two spiral galaxies. The outer rim of a small, foreground galaxy is silhouetted in front of a larger background galaxy. Skeletal tentacles of dust can be seen extending beyond the small galaxy's disk of starlight.

NGC 253
©NASA, ESA, and The Hubble Heritage Team (STScI/AURA). Acknowledgement: B. Holwerda (Space Telescope Science Institute) and J. Dalcanton (University of Washington)
Astronomers used Hubble's Advanced Camera for Surveys to snap images of NGC 253 when they spied the two galaxies in the background. From ground-based telescopes, the two galaxies look like a single blob. But the Advanced Camera's sharp "eye" distinguished the blob as two galaxies, cataloged as 2MASX J00482185-2507365.

Such outer dark dusty structures, which appear to be devoid of stars, like barren branches, are rarely so visible in a galaxy because there is usually nothing behind them to illuminate them. Astronomers have never seen dust this far beyond the visible edge of a galaxy. They do not know if these dusty structures are common features in galaxies.

Understanding a galaxy's color and how dust affects and dims that color are crucial to measuring a galaxy's true brightness. By knowing the true brightness, astronomers can calculate the galaxy's distance from Earth.
Read More...
Telescope

Wild, Hidden Cousin Of SN 1987A: Powerful Supernova Caught By Web Of Telescopes


Science Daily
Thu, 25 Sep 2008 13:17 UTC
The supernova, called SN 1996cr, was first singled out in 2001 by Franz Bauer. Bauer noticed a bright, variable source in the Circinus spiral galaxy, using NASA's Chandra X-ray Observatory. Although the source displayed some exceptional properties Bauer and his Penn State colleagues could not identify its nature confidently at the time.

Circinus galaxy
©X-ray (NASA/CXC/Columbia/F.Bauer et al); Visible light (NASA/STScI/UMD/A.Wilson et al.)
This composite image shows the central regions of the nearby Circinus galaxy, located about 12 million light years away. Data from NASA's Chandra X-ray Observatory is shown in blue and data from the NASA/ESA Hubble Space telescope is shown in yellow ("I-band"), red (hydrogen emission), cyan ("V-band") and light blue (oxygen emission). The blue source near the lower right hand corner of the image is the supernova SN 1996cr, that has finally been identified over a decade after it exploded. The supernova was first singled out in 2001 as a bright, variable object in a Chandra image, but it was not confirmed as a supernova until years later, when clues from a spectrum obtained with ESO's Very Large Telescope led the team to start the real detective work of searching through data from 18 different telescopes, both ground- and space-based, nearly all of which was in the archives. SN 1996cr is one of the nearest supernovae in the last 25 years.

It was not until years later that Bauer and his team were able to confirm that this object was a supernova. Clues from a spectrum obtained by ESO's Very Large Telescope led the team to start the real detective work of searching through data from 18 different telescopes, both ground- and space-based, nearly all of which existed. Because this object was found in an interesting nearby galaxy, the public archives of these telescopes contained abundant observations.
Read More...