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EARTH'S MYSTERIOUS SECOND MAGNETIC FIELD REVEALED IN STUNNING NEW SWARM IMAGES

Updated | You may know that the Moon is behind our oceans’ tides, drawing water to and from coasts with its gravitational pull. You might not know that this movement generates a weak magnetic field. The huge bodies of electrically-conductive salt water create a magnetic signal as they ebb and flow.

Now, a constellation of satellites has mapped this elusive magnetic field in impressive detail. Dubbed “Swarm,” the European Space Agency mission results stunned scientists at the European Geosciences Union General Assembly 2018 in Vienna, Austria.

Elusive magnetic field

The field has been incredibly difficult to track because it is so small. "It's a really tiny magnetic field. It's about 2-2.5 nanotesla at satellite altitude, which is about 20,000 times weaker than the Earth's global magnetic field," Nils Olsen, head of geomagnetism at the Technical University of Denmark, told BBC News.

A screenshot of the ESA's magnetic tides map.ESA

Hot, swirling liquid iron in the Earth's outer core generates the vast majority of its magnetism. The ocean field, along with other factors like magnetized rocks in the Earth's crust, makes a small but important contribution to the overall magnetic signal of the planet.

This newly-tracked magnetic field, Olson said in a statement, “gives us a truly global picture of how the ocean flows at all depths.”

Mysterious electrical activity inside Earth

Earth, as pictured from the NASA/NOAA Suomi National Polar-orbiting Partnership spacecraft on April 9, 2015.NASA

It can help scientists understand more about climate change, and even electrical activity deep within Earth's interior. “Since oceans absorb heat from the air, tracking how this heat is being distributed and stored, particularly at depth, is important for understanding our changing climate," Olson explained.

Read more: Earth’s Magnetic Field Is about to Flip—and a ‘Giant Lava Lamp’ in Earth’s Core Is The Driving Force

The magnetic signature of the tides causes a "weak magnetic response" deep below the sea, Olson added. Swarm will help scientists understand more about the mysterious electrical goings-on of our planet's lithosphere and upper mantle. Electromagnetic data from deep inside Earth gives scientists vital information about its structure and about the tectonic activity that drives earthquakes and volcanic eruptions.

This article has been updated to include more information about the sources of Earth's magnetic signal.

(newsweek)

NASA’S 4K MOON VIDEO TOUR WILL BLOW YOU AWAY

NASA has released a spectacular 4K resolution video tour of the Moon based on data and images collected by the Lunar Reconnaissance Orbiter (LRO), which has been orbiting our only natural satellite since 2009.

The tour visits numerous sites of interest (detailed individually in this Tumblr post) that LRO has helped to shed light on. Many of these are on the Moon’s near-side and are familiar to both professional and amateur astronomers alike, while others can only be clearly seen from space.

The LRO data is helping NASA plan future lunar missions, while also providing new insights into the moon’s structure and evolution.

One stop on the tour is the Moon’s North Pole. Using LRO data, scientists have identified mountain peaks and crater rims in this region that have consistent sun exposure. These areas could be ideal sites to place solar panels for the support of future human missions.

Another feature visited by the tour is the Aristarchus Plateau, which contains a crater so bright it is actually visible with the naked eye from Earth. This region is covered in rocks from volcanic eruptions and marked by river-like structures created by ancient lava flows. It is particularly interesting to researchers, not only as a potential landing site, but also because it serves as a record of the Moon’s volcanic history.

The tour also stops by the Texas-sized Orientale Basin—the best-preserved impact structure on the Moon. Topography data from LRO combined with gravity measurements from NASA’s GRAIL spacecraft has revealed the structure below the basin, helping scientists understand the geological consequences of large impacts.

Image of the Moon taken by NASA's Lunar Reconnaissance Orbiter (LRO).NASA

The video also looks at the South Pole—where some of the coldest temperatures in the Solar System have been recorded—the vast Pole-Aitken Basin on the Moon’s far side—which extends across more than 1,550 miles—and the mysterious Tycho Crater—whose origins remain unexplained.

“LRO was designed as a one-year mission,” NASA wrote in the Tumblr post. “Thanks to its many orbits around the Moon, we have been able to expand on lunar science from the Apollo missions while paving the way for future lunar exploration. And as the mission continues to gather data, it will provide us with many more opportunities to take a tour of our Moon.”

(newsweek)

An ancient lake holds secrets to the Mayan civilization’s mysterious collapse, study finds

The sediment under a lake in Mexico contains some of the long-sought answers to the mystery of the Mayan demise.

Ancient Mayans, primarily concentrated in what is now the Yucatan Peninsula, were among the most advanced civilizations of their time. Mayans were some of the first to build cities. They used astronomy to advance agricultural production, and they created calendars and used advanced mathematics. But despite all of their progress, the Mayan empire, built over thousands of years, may have crumbled in just a few hundred.

Scientists have several theories about why the collapse happened, including deforestation, overpopulation and extreme drought. New research, published in Science Thursday, focuses on the drought and suggests, for the first time, how extreme it was.

While analyzing sediment under Lake Chichancanab on the Yucatan Peninsula, scientists found a 50 percent decrease in annual precipitation over more than 100 years, from 800 to 1,000 A.D. At times, the study shows, the decrease was as much as 70 percent.

The drought was previously known, but this study is the first to quantify the rainfall, relative humidity and evaporation at that time. It's also the first to combine multiple elemental analyses and modeling to determine the climate record during the Mayan civilization demise.

Matthew Lachniet, a professor of geosciences at the University of Nevada at Las Vegas, who was not involved in the study, said the quantification of the drought is important, because it illustrates the power of natural climate variability alone.

“Humans are affecting climate. We’re making it warmer and it’s projected to become drier in Central America,” Lachniet said. “What we could end up with is double-whammy of drought. If you coincide drying from natural causes with drying from human causes, then it amplifies the strength of that drought.”

The new research analyzed sediment cores, something climate scientists commonly do to determine conditions of the past, using the ancient dirt like a geological time capsule. Each layer of sediment buried deep underground contains evidence of rainfall, temperature and even air pollution. Via chemical processes and interactions, the climate conditions are “recorded” in the surface soil at the time and eventually buried. Scientists can bore a deep core of dirt and carefully analyze it layer by layer, year by year, to reconstruct a timeline.

For this study, scientists painstakingly examined the layers of mud and clay in the cores from under Lake Chichancanab. During dry periods, the lake volume would have shrunk, said Nick Evans, a graduate student studying paleoclimatology at Cambridge University and first author of the study. As the water evaporated, lighter particles would have evaporated first, leaving behind heavier elements.

If the drought was intense and long-lasting, gypsum crystals formed and incorporated existing lake water directly into their structure. The “fossil water” inside the crystals allowed Evans and his co-authors to analyze the properties of the lake water during each period.

“It’s as close as you’ll ever get to sampling water in the past,” Evans said.

The chemical composition of the fossil water indicated periods of drought in the Mayan timeline and revealed how long and intense this particular drought was.

Many theories about the drought triggers exist, but there is no smoking gun some 1,000 years later. The drought coincides with the beginning of the Medieval Warm Period, thought to have been caused by a decrease in volcanic ash in the atmosphere and an increase in solar activity. Previous studies have shown that the Mayans’ deforestation may have also contributed. Deforestation tends to decrease the amount of moisture and destabilize the soil. Additional theories for the cause of the drought include changes to the atmospheric circulation and decline in tropical cyclone frequency, Evans said.

Evans and his team hope their research will help archaeologists understand how the ancient drought may have impacted Mayan agriculture at a critical time in their history.

Currently, vast areas of North America, northern Africa, the Middle East, Southwest Asia and most of Australia are in significant drought, according to the National Oceanic and Atmospheric Administration’sGlobal Drought Information System. Sociopolitical research suggests that drought may cause war, famine and large human migrations. And many countries affected lack the resources to cope.

“Drought does have the potential to be a driving force for a lot of the issues that can cause civilization stress,” Evans said. He noted, though, that today’s globalized economy and modern technology have the potential to prevent a Mayan-style, world-ending drought. Probably.