Three European satellites launched Friday on a mission to study why the magnetic field surrounding Earth appears to be weakening.
The four-year study will collect data and map the field, which protects the planet (and us) from solar radiation.
Scientists say the field’s strength has weakened by about 15 percent in the last 200 years.
The weakening could be a sign of “polarity reversal" - when the field flips end-to-end, turning north into south. The phenomenon occurs every 200,000 to 300,000 years. But the last time the field flipped was almost 800,000 years ago.
The magnetic field is believed to be generated by the Earth’s molten iron core. The field reaches thousands of miles into space and creates a bubble around the earth. It’s what makes compasses work, and aids everything from navigation systems to animal migrations…
… is a lead molybdate mineral with the formula PbMoO4. It can be most often found as thin tabular crystals with a bright orange-red to yellow-orange color, sometimes brown, although the color can be highly variable. In its yellow form it is sometimes called “yellow lead ore”.
It crystallizes in the tetragonal system, often occurring as stubby, pyramidal or tabular crystals. It also occurs as earthy, granular masses. It is found in many localities, associated with lead ores as a secondary mineral associated with the oxidized zone of lead deposits. It is also a secondary ore of molybdenum, and is sought by collectors…
This scene shows a section of Ismeniae Fossae that straddles the southern highlands–northern lowlands of Mars. The 2 km-wide curvilinear trough that runs through this image contains numerous parallel grooves and ridges comprising material from the trough walls and material that has been dragged along the floor by ancient glaciers and ice-rich flows.
In the left portion of the scene the channel truncates a roughly 25 km-wide crater. Material in the crater walls has slumped down into the channel, smoothing over the grooved floor. Around this crater, and elsewhere in Ismeniae Fossae, clusters of circular to elliptical, partially interconnected depressions are observed. These may be either secondary impact craters from debris flung out by larger impact craters, or collapse pits caused by the sublimation of subsurface ice…
Big Pic: An Overactive Russian Volcano Covers Kamchatka In Ash
Russia’s Klyuchevskaya volcano, one of the most active in the world, has been erupting since mid-August. Last month, it became even more intense, spewing ash from its summit (16,000 feet above sea level) in a plume that reached 32,000 feet above the Earth, along with fountains of lava. NASA’s Landsat 8 satellite grabbed a shot of Klyuchevskaya, located on Russia’s volcano-denseKamchatka peninsula, in late October after its most explosive activity had calmed down.
This false-color image shows snow and ice as blue-green, ash, clouds and steam as gray, and lava as red…
Western Norway’s fjords—like Nærøyfjorden, northeast of Bergen and a UNESCO World Heritage site—look like fingers of the sea intruding into the land. But they are also receptacles for fresh water pouring off the peaks and ridges that surround them.
Pristine “Islands in the Sky” Are Window on Evolution
Unique plants and animals of South America’s tepuis (mesas) reveal rich secrets.
by Brian Clark Howard
Tepuis—high sandstone mesas that erupt from surrounding rain forest in southern Venezuela and part of adjacent Guyana and Brazil—have captivated scientists for centuries. Remote, ancient outcrops that soar up to 10,000 ft (3,000 m) high, tepuis have long been thought of as crucibles of evolution. Recent research confirms their biological importance, but also shatters the most romantic notions about them.
Tepuis are the real “islands in the sky,” Bruce Means, a herpetologist and ecologist at Florida State University in Tallahassee, because their height—typically 5,000 to 10,000 ft (1,500 to 3,000 m)—effectively cuts them off from the surrounding rain forest. That means they host unique habitats and unique creatures.
The rock that makes up tepuis is thought to be 1.6 to 1.8 billion years old, said Means, who has visited the mountains with support from National Geographic. Part of a vast region called the Guiana Shield, the mesas were uplifted around 40 to 50 million years ago, and then the surrounding rock eroded away. Scientists had assumed that erosion would have left plants and animals stranded on the summits, cut off from the surrounding landscape for tens of millions of years…
(read more: National Geographic)
photos: Kukenan Tepuy in Gran Sabana National Park, Venezuela by Paolo Costa Baldi; Pebble Toad by Joe Riis, National Geo
The Pleistocene Epoch is typically defined as the time period that began about 1.8 million years ago and lasted until about 11,700 years ago. The most recent Ice Age occurred then, as glaciers covered huge parts of the planet Earth.
There have been at least five documented major ice ages during the 4.6 billion years since the Earth was formed — and most likely many more before humans came on the scene about 2.3 million years ago…
Big calderas point to early magma outbursts that shaped the red planet.
by Dan Vergano
Massive “supervolcanoes” erupted across the northern face of Mars some 3.7 billion years ago, planetary scientists suggest. The eruptions likely blasted lava, sulfur, and ash across the red planet, altering its atmosphere and surface.
The planets of the inner solar system—Earth, Mars, Venus, and Mercury—started their lives as boiling-hot balls of rock, which cooled to feature thin crusts battered by asteroid and comet impacts. On Mars, that early crust was perhaps also punctured by supersize volcanoes with calderas more than 30 mi (50 km) wide, a newly identified kind of volcanism on the red planet…