Archives for category: Earth Observatory

A Clearer View of Hazy Skies

October 4, 2014 //

When astronauts talk about viewing Earth from space, the conversation often turns to the planet’s mesmerizing beauty. They describe views of aquamarine coral reefs glimmering amidst the deep blue ocean; of armies of sand dunes marching across deserts; of clouds and lightning flashes dancing through the atmosphere.

For many, the view is deeply humbling. “For the first time in my life, I saw the horizon as a curved line. It was accentuated by a thin seam of dark blue light: the atmosphere,” said Ulf Merbold, a German astronaut who flew on Space Shuttle Columbia in 1983. “This was not the ‘ocean’ of air I had been told it was…I was terrified by its fragile appearance.”

For some astronauts, that thin blue line has appeared quite vulnerable. Many have noticed palls of haze lingering over parts of the world, the result of millions of tiny particles drifting in the atmosphere. Aerosol particles, which can be either liquid or solid, obstruct sunlight and cause distinct and vibrant features to blend into a hazy, featureless mélange of gray.

The particles that affect visibility have many sources, some of them natural. For instance, winds blow bits of dust and dried soil aloft; volcanoes occasionally belch thick plumes of ash; forest fires produce smoke; even vegetation and plankton can emit substances that contribute to haze.

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NASA Earth Observatory, June 2014

Categories 2014, Air Quality, Earth Observatory

The Eight-Thousanders

October 4, 2014 //

Eight thousand is a perfectly arbitrary number. Yet, no other number looms larger for mountain climbers.

Fourteen mountain peaks stand taller than 8,000 meters (26,247 feet). There could have been many more of these “eight-thousanders” if the French commission that established the length of the meter (in 1793) had made it just a bit shorter; there would be hardly any if they had made the meter longer. The decision to make a meter equivalent to one ten-millionth of the distance between the equator and the North Pole left the world with fourteen 8K peaks. All of them are found in either the Karakoram or Himalayan mountain ranges of central Asia.

Fourteen is a number that pushes climbers to the point of obsession. It’s big enough that only the most ambitious consider climbing all of them, but small enough that doing so over a lifetime still seems possible. Even in the United States, a country where most people shun metric measurements, climbers dream of ascending the eight-thousanders. The “twenty-six-thousand, two-hundred-and-forty-seven-footers” hardly has the same ring.

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NASA Earth Observatory, September 2013

Tags Geology

Categories 2013, Earth Observatory, NASA

So Much More To Learn

February 11, 2013 //

The atmosphere was electric at Providence Landing Park in Lompoc, California as the first stage of an Atlas 5 rocket ignited in the distance on February 11, 2013.

Cheers erupted at 10:02 a.m. from the hundreds of people gathered there as the rocket rose, gathered itself, then surged into a perfect blue sky over Vandenberg Air Force Base. As the cheers subsided, it was surprisingly quiet for a moment as awe sank in, save for the patter of scores of cameras clicking in unison.

A full 30-or-so seconds later, the sound arrived. You could feel the roar in the ground. The Landsat Data Continuity Mission (LDCM), the latest satellite in the world’s longest-running series of Earth-observing satellites, was on its way to space.

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Earth Observatory, Earth Matters blog, February 2013

Categories 2013, Adventure, Earth Matters, Earth Observatory, NASA

Saving Siding Spring Observatory

February 7, 2013 //

On the afternoon of January 14, 2013, a fierce bushfire swept across the campus of Siding Spring Observatory, a world-class astronomy facility on a ridge in Australia’s Warrumbungle National Park. The observatory is home to some of the most powerful sky-mapping telescopes in the world.

Ten years earlier, a brush fire devastated one of Australia’s other top observatories, so the staff of Siding Spring feared that history was repeating itself. As the fire reached the observatory’s campus, cameras and telescopes sent back disturbing images of flames lapping at the doorsteps of buildings and smoke billowing overhead.

By nightfall on January 14, the situation looked dire to the scientists and staff who had evacuated and were left to monitor the situation online. A handful of buildings on the campus were on fire. At one point, a thermometer on campus recorded a spike in air temperatures to 100 degrees Celsius (212 degrees Fahrenheit).

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Earth Observatory, February 2013

Categories 2013, Earth Observatory, NASA, Wildfires

Bushfire Burn Scar near Dunalley, Tasmania

January 27, 2013 //

In January 2013, intense bushfires blazed in Tasmania, an island state of Australia. One of the hardest hit towns was Dunalley, a fishing village on the eastern coast. A blaze destroyed at least 80 homes—about 30 percent of the town— when it tore through the area on January 4, 2013. In the nearby village of Connellys Marsh, 40 percent of the buildings were destroyed. Primrose Sands lost several homes as well.

The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA’s Terra satellite captured this image of the charred landscape on January 14. Vegetation-covered land is red in the false-color image, which includes both visible and infrared light. Patches of unburned forest are bright red, in contrast with areas where flecks of light brown indicate some burning. The darkest brown areas are the most severely burned. Buildings, roads, and other developed areas appear light gray. Clouds are white.

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Earth Observatory, February 2013

Categories 2013, Earth Observatory, Wildfires

Mine Collapse in Turkey

June 21, 2012 //

Mine Collapse in Turkey

At 10 a.m. on February 10, 2011, disaster struck the Çöllolar coalfield in central Turkey, near the city of Elbistan. The northeastern wall of an open-pit mine collapsed, sending about 50 million tons of material into the mine. The debris buried and killed ten workers.

The collapse was the second at the same mine within a week. Four days earlier, a smaller landslide damaged the opposite wall and killed one person. According to a United Nations report, debris from the two landslides covered 2.73 square kilometers (1 square mile). The larger landslide extended 350 meters (1,150 feet) past the original perimeter of the pit. Inadequate drainage of the mine walls likely caused the landslides, according to Caner Zanbak, an environmental adviser to the Turkish Chemical Manufacturers Association.

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Earth Observatory, June 2012

Categories 2012, Earth Observatory, Mining, NASA, Satellite Puzzler