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End Of Earth By Nasa

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ScienceCasts Why the World Didnt End Yesterday

music Why the World Didn't End Yesterday, presented by Science@NASA Dec. 22, 2012: If you're watching this tutorial, it means one thing: The World Didn't End Yesterday. According to media reports of an ancient Maya prophecy, the world was supposed to be destroyed on Dec. 21, 2012. But look around you. 'The whole thing was a misconception from the very beginning,'

says John Carlson, director of the Center for Archaeoastronomy. 'The Maya calendar did not end on Dec. 21, 2012, and there were no Maya prophecies foretelling the end of the world on that date.' The truth, he says, is more interesting than fiction. Carlson is a hardnosed scientist a radio astronomer who earned his degree studying distant galaxies. He became interested in the 2012 phenomenon 35 years ago when he attended a meeting of the American Association for the Advancement of Science

and learned about the Maya. Where the rain forests of Mesoamerica now stand, a great civilization once flourished. The people of Maya society built vast cities with a population density comparable to modern Los Angeles County. They mastered astronomy and developed an elaborate written language. Most impressive, to Carlson, was their expansive sense of time.

'The times Mayas used dwarf those currently used by modern astronomers,' he explains. 'According to our science, the Big Bang occurred 13.7 billion years ago. There are dates in Mayan ruins that stretch back a billion billion times farther than that.' The Maya Long Count Calendar was designed to keep track of such long intervals. 'It is the most complex calendar system ever developed.' Written using modern typography,

the Long Count Calendar resembles the odometer in a car. Because the digits rotate, the calendar can 'roll over' and repeat itself; this repetition is key to the 2012 phenomenon. According to Maya theology, the world was created 5125 years ago, on a date we would write 'August 11, 3114 BC.' At the time, the Maya calendar looked like this:

On Dec. 21, 2012, it is exactly the same: In the language of Maya scholars, '13 Bak'tuns' elapsed between the two dates. This was a significant interval in Maya theology, but, stresses Carlson, not a destructive one. None of the thousands of ruins, tablets, and standing stones that archeologists have examined

NASA A Year in the Life of Earths CO2

Hi, this is Bill Putman. I'm a climate scientist at NASA's Goddard Space Flight Center. What you're looking at is a supercomputer model of carbon dioxide levels in the Earth's atmosphere. The visualization compresses one year of data into a few minutes. Carbon dioxide is the most important greenhouse gas affected by human activity.

About half of the carbon dioxide emitted from fossil fuel combustion remains in the atmosphere, while the other half is absorbed by natural land and ocean reservoirs. In the Northern Hemisphere, we see the highest concentrations are focused around major emission sources over North America, Europe and Asia. Notice how the gas doesn't stay in one place. The dispersion of carbon dioxide is controlled by the largescale weather patterns within the global circulation. During spring and summer in the Northern Hemisphere, plants absorb a substantial amount of carbon dioxide through photosynthesis, thus removing some of the gas from the atmosphere.

We see this change in the model as the red and purple colors start to fade. Meanwhile, in the Southern Hemisphere, we see the release of another pollutant—carbon monoxide. This is a gas that's both harmful to the environment and to humans. During the summer months, plumes of carbon monoxide stream from fires in Africa, South America and Australia, contributing to high concentrations in the atmosphere.

Notice how these emissions are also transported by winds to other parts of the world. As summer transitions to fall, and plant photosynthesis decreases, carbon dioxide begins to accumulate in the atmosphere. Although this change is expected, we're seeing higher concentrations of carbon dioxide accumulate in the atmosphere each year. This is contributing to the longterm trend of rising global temperatures.

The Orbiting Carbon Observatory2, or OCO2, will be the first NASA satellite mission to provide a global view of carbon dioxide. OCO2 observations and atmospheric models like GEOS5 will work closely together to better understand both human emissions and natural fluxes of carbon dioxide. This will help guide climate models toward more reliable predictions of future conditions across the globe.

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