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End of world as we know it Impacts can be caused by stray rubble from Asteroid Belt and the rocky snowballs that travel in highly elliptical orbits in the comet cloud Trends International Space Station crew member Russian cosmonaut Fyodor Yurchikhin (L) waves as US astronaut Shannon Walker walks after putting on their space suits at the Baikonur Cosmodrome. — Reuters photograph
THIS UNIVERSE |
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End of world as we know it APocalyptic thought has a tradition that dates to the Persian prophet Zoroaster in the 14th century BC. Recently, anxiety has grown over the prediction of the end of the world in the Mayan calendar. It’s true that the Mayan odometer will hit zeros on December 21, 2012, as it reaches the end of a 394-year cycle called a baktun. But this baktun is part of a larger 8,000-year cycle called a pictun, and there’s no evidence that anything astronomically untoward will happen as the current baktun slides into the next. However, that hasn’t stopped the feverish speculating that sells books and cinema tickets. What kind of catastrophe would it take to end the world? Astronomical intruders provide a potentially serious threat. Impacts can be caused by stray rubble from the Asteroid Belt and the rocky snowballs that travel in highly elliptical orbits in the comet cloud. There are many fewer large bits of debris than small bits, so the interval between large impacts is much longer than the interval between small impacts. That’s good news. Every century or so, a 10-meter meteor slams into the Earth with the force of a small nuclear device. Tunguska was the site of the last, in 1908, and it was pure luck that that meteor landed in the uninhabited wilderness of Siberia. Every few thousand years, the Earth can pass through unusually thick parts of the debris trail of comets, turning the familiar light show of a meteor shower into a deadly firestorm. Roughly every 100,000 years, a projectile hundreds of meters across unleashes power equal to the world’s nuclear arsenals. The result is devastation over an area the size of England, global tidal waves (if the impact is in the ocean), and enough dust flung into the atmosphere to dim the Sun and kill off vegetation. That could ruin your day. Then there’s the “Big One”. About every 100 million years, a rock the size of a small asteroid slams into the Earth, causing global earthquakes, kilometre-high tidal waves, and immediately killing all large land animals. Creatures in the sea soon follow, as trillions of tons of vapourised rock cause drastic cooling and the destruction of the food chain based on photosynthesis. There’s good evidence that this happened 65 million years ago and our tiny mammal ancestors were the beneficiaries as the giant lizards were extinguished. A hundred million years sounds like a safe buffer, but the next one could happen at any time. But you can take it off your worry list—astronomers have it covered. A network of ground-based telescopes scans the skies for bits of rogue rubble larger than a few hundred meters. That’s ample time to dust off the nuclear arsenals for an interception mission if we had to. Unfortunately, the Dr Strangelove approach creates lethal shrapnel travelling in the same direction as the original object; a smarter strategy is to send a spacecraft alongside it and gently “tug” it with gravity onto a slightly different trajectory. When massive stars exhaust their nuclear fuel, the result is a titanic explosion called a supernova. The dying star brightens to rival an entire galaxy and emits high-energy particles that can destroy the ozone layer of a planet like the Earth if it occurs within 30 light years. The demise of large North American mammals 41,000 years ago has been linked to a supernova, and several other mini-extinctions may be tied to the cataclysm of stellar death. A supernova is a small squib compared to a hypernova. In this dramatic and rare event, the violent collapse of a very massive star ejects jets of gas and high-energy particles at close to the speed of light, and for a few moments the star outshines the entire universe in gamma rays. If a hypernova went off within 1,000 light years, and the Earth was within the narrow cone of high-energy radiation, we’d experience an immediate global conflagration. It’s brutal luck if a hyper nova ever goes off with its beam aimed at us. On longer time scales, attention turns to the sheltering Sun. Our constant companion is midway through its conversion of hydrogen into helium. In about 5 billion years, its guttering flame will be extinguished. The Sun’s diffuse envelope will engulf the Earth and turn it into a lifeless cinder. This is death by stellar cremation. If that seems like a comfortably distant prospect, the biosphere will actually die much sooner. The Sun burns hot as it gets older, and in 500 million years a turbocharged version of global warming will turn the Earth into a global desert. That gives us plenty of time to find better real estate. Titan looks promising. It already has the nitrogen—just add oxygen and presto! Our second home. And those wild-eyed rocket scientists who want to save us from asteroids have a thrilling plan up their sleeves: deliberately bring an asteroid in close, and with each pass it will transfer a little energy to the Earth and nudge it further from the Sun. After a few million close calls we’ll have migrated to a more hospitable orbit. —By arrangement with
The Independent
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Trends CAPE CANAVERAL, Florida: Two US astronauts and a Russian cosmonaut blasted off aboard a Russian Soyuz rocket from Kazakhstan for a two-day trip to the International Space Station. The rocket took off from the Baikonur Cosmodrome, marking the 100th flight to the orbital outpost, a $100-billion project of 16 nations that is nearing completion after more than a decade of construction 220 miles above the Earth. Japanese space probe finds unique asteroid dust SYDNEY: A Japanese space probe has landed in the Australian outback after a seven-year voyage to an asteroid, safely returning a capsule containing a unique sample of dust, Japanese mission controllers said. The Hayabusa probe blazed a spectacular trail over Australia before slamming into the desert at around midnight local time, ending a journey to the near-Earth asteroid Itokawa that began in 2003. Cleared forests lead to rise in malaria in Brazil WASHINGTON: Clearing forests in the Amazon helps mosquitoes thrive and can send malaria rates soaring, U.S. researchers reported. They found a 48 per cent increase in malaria cases in one county in Brazil after 4.2 per cent of its tree cover was cleared. Their findings, published in the journal Emerging Infectious Diseases, shows links between cutting down trees, a rise in the number of mosquitoes and infections of humans. “It appears that deforestation is one of the initial ecological factors that can trigger a malaria epidemic,” said Sarah Olson of the University of Wisconsin, who worked on the study. Undersea robot aims for 3-D image of BP oil plume WASHINGTON: Scientists are gearing up for a 12-day trip in the Gulf of Mexico with an undersea robot they hope will capture 3-D images of oil plumes from the BP spill. Oceanographers and others have been monitoring the plumes of oil, gas and dispersant chemicals coming from the broken BP wellhead since soon after the April 20 explosion on the Deepwater Horizon drilling platform. The scientists’ robotic vehicle would try to figure out how big the plume is, where it is and what it is made of, said Christopher Reddy, director of the Coastal Ocean Institute at Woods Hole Oceanographic Institution. — Reuters
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THIS UNIVERSE Is it true that a person standing near a fast moving train gets blown away with it? If yes, please explain. I think one can easily understand a physical effect. When you have a fast moving train, one of the things it has to do is keep pushing away a lot of air in its path. This creates a partial vacuum that has to be filled by air rushing in from the sides and from behind. It is, therefore, natural that there would be a push of the air towards the train from the side. You might not be blown away but you might be sucked in towards the track. What is the smallest particle of an element that can take part in a chemical reaction? This curious question really made me think, though I normally would not. Chemistry is something that can happen between atoms and molecules. Some outer electrons are exchanged or shared. So, the smallest particle that can take part in a chemical reaction would be of atomic size. In physical units, it would be about a hundred millionth of a centimeter. Interaction does happen between much smaller particles, e.g., between two protons. But we do not call this a chemical reaction. That is not chemistry but particle physics. Can the earth’s core ever
stop rotating? A separation between the crust of the earth and its inner core can be imagined, in the sense that the two might sometime stop co-rotating. Not easy to imagine how it might happen. Interest on this question arises from the fact that the convection of the liquid conducting core, along with the rotation of the planet, somehow produces the Earth magnetic field. A disturbance in the co-rotation would produce a disorder, at least initially, in the convection of the conducting core and might even lead to disappearance and then reversal of the magnetic field, after an order in the convection currents is restored. Since it is a known fact that over geologic times the earth magnetic field has reversed several times, it is possible that ideas that some events like the one mentioned might be valid. Mind you we are not talking of stopping the rotation of the core, only the possibility of disturbing the co-rotation of the core and the crust. (I do not think stopping has any physical possibility). Some scientists have suggested that collision with large comets or asteroids, or even a nuclear winter, might move enormous amounts of water in earth’s oceans across latitudes in a manner to change the moment of inertia of the earth crust causing a break in the co-rotation of the crust and the core. Over long geologic times, such happenings are quite likely. |
APocalyptic thought has a tradition that dates to the Persian prophet Zoroaster in the 14th century BC. Recently, anxiety has grown over the prediction of the end of the world in the Mayan calendar.
It’s true that the Mayan odometer will hit zeros on December 21, 2012, as it reaches the end of a 394-year cycle called a
baktun.
CAPE CANAVERAL, Florida: Two US astronauts and a Russian cosmonaut blasted off aboard a Russian Soyuz rocket from Kazakhstan for a two-day trip to the International Space Station. The rocket took off from the Baikonur
Cosmodrome, marking the 100th flight to the orbital outpost, a $100-billion project of 16 nations that is nearing completion after more than a decade of construction 220 miles above the Earth.
