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... GLOBAL NEWS ... NEWS. ... had nightmares about being killed after being given the heart of a murdered child. However, the only case recognised by the scientific community is that of a 15- year-old Australian girl whose blood type changed following a liver transplant. (Source: The Telegraph, UK, 16 March 2008, http://tinyurl.com/3pawyy) vicinity of the geographic poles all the time. The north magnetic pole currently resides in the Canadian Arctic. However, at relatively regular intervals throughout the 4.5-billion-year history of the planet, the magnetic poles have flipped completely. A few thousand years before a reversal, the magnetic field gradually gets weaker—something which could cause problems for inhabitants of the planet. "The Earth's magnetic field is important for shielding the atmosphere, and us, from damage caused by the solar wind," explained Biggin. "It's also used by us and other species for navigation." Current records suggest that we are long overdue for our next reversal, he said. "On average, there is a reversal around every 400,000 years, but this varies a lot." The geological record suggests that the last reversal was around 800,000 years ago. Furthermore, there is already evidence to show that the field has been weakening over the last few centuries. Archaeological remains suggest that the field was far stronger in the time of the Roman Empire, some 2,000 years ago. (Source: Cosmos Online, 5 May 2008, http://www.cosmosmagazine.com/node/1967) events that occur periodically on Earth. Writing in the Monthly Notices of the Royal Astronomical Society, the scientists at the Cardiff Centre for Astrobiology who built the computer model say that during certain periods in the bounce, gravitational forces from surrounding gas and dust clouds could dislodge comets from their paths. These comets could then plunge into our solar system, some of them colliding with the Earth. The Cardiff team says that when we pass through the galactic plane every 35 to 40 million years, the chances of a comet collision are increased tenfold. Intriguingly, evidence from craters on Earth also suggests we suffer more collisions approximately every 36 million EARTH'S POLES LONG OVERDUE FOR REVERSAL Awe of the Earth's magnetic poles could happen sooner than we think, according to Dutch scientists who report that the planet's magnetic field is becoming gradually less stable. A reversal could affect everything from navigation and communications equipment to the composition of the atmosphere, say avnarte years. "It's a beautiful match between what we see on the ground and what is expected from the galactic record," noted Professor William Napier of the Cardiff Centre. Professor Napier contends that the periods of comet bombardment also coincide with mass extinctions, such as that of the dinosaurs 65 million years ago. But while the bounce effect may have been bad news for dinosaurs, it may also have helped life to spread. The scientists suggest the impact may have thrown debris containing micro-organisms out into space and across the universe. "This is a seminal paper which places the comet-life interaction on a firm basis, and shows a mechanism by which life can be dispersed on a galactic scale," commented Centre director Professor Chandra Wickramasinghe. And in case you're interested in when the next comet infestation might occur, our present position in the galaxy suggests we are now very close to another such period. (Source: Cardiff University News Centre, 3 May 2008, http://www.cardiff.ac. uk/news/index.html; via Science A Go Go, 5 May 2008, http://tinyurl.com/6docvz) experts. The report, published online on 4 May in the UK journal Nature Geoscience, found that reversals have been far more common in the last 200 million years than they were deep in the planet's history. Researchers, led by Andrew Biggin of the University of Utrecht in The Netherlands, made the discovery by analysing rocks formed between 2.45 to 2.82 billion years ago. The story of the Earth's magnetic field is written in rocks over time. Because these rocks become "magnetised" at the time of their formation, scientists can discover which direction the poles were facing and how strong the Earth's magnetic field was at that time. The magnetic poles wander around the SOLAR SYSTEM'S "BOUNCE" LINKED TO MASS EXTINCTIONS AN computer model of our solar system's movement relative to the Milky Way indicates that it "bounces" up and down through the plane of the galaxy—a cycle that scientists say is a "beautiful match" with the mass extinction frm HERE To WARM \ You oF THE #LoBAL consPreacy oF BAD “s CARTEOMTETS . a yo consPreacy oF BAD eit U of THE 6LoB8AL “_CARTOOMISTS . = Gide hae es cre ‘a at es LASS —_ Cen & i U meres Pe — — SEA ICE LEVELS REACH 25-YEAR HIGH lobal sea ice in April 2008 reached levels that were unprecedented for the month of April in over 25 years. Levels were the third highest for April since record-keeping began in 1979, exceeded only by levels in 1979 and 1982. This continues a pattern established earlier in 2008. Global sea ice in March 2008 was the third highest on record for March, while January 2008 sea ice was the 8 = NEXUS JUNE — JULY 2008 www.nexusmagazine.com