April 2016 on EARTH Magazine

Geomedia: Film: 'A Beautiful Planet' inspires with vivid views of life on and off Earth

Thu, 28 Apr 2016 17:18:48 -0400

An endless sea of bright dots surrounds you amid the otherwise darkened expanse as you slowly approach a swirling, recognizable cloud of glowing light — the Milky Way. As the galaxy grows to fill the screen, you feel as if you are heading home toward Earth. This sensation of being a crewmember on a spaceship stays with you throughout the new documentary film, “A Beautiful Planet," as well as after it’s over — which is just what the filmmakers intended.

Geologic Column: May: Nature's forces in collision

Thu, 21 Apr 2016 16:01:19 -0400

As a day, May 1 has probably had more festivals and events associated with it than any other day of the year. Credit: Copyright Corbis Images.

May is named for Maia, the Greek goddess of fertility, and eldest of the seven Pleiades sisters. Orion, the hunter, after meeting the sisters, was so enamored of the young women that he pursued them relentlessly. Taking pity on their plight, Zeus changed the sisters into a flock of doves and set them in the heavens as a striking constellation of stars in the northeast quadrant of the sky. Maia’s festival was held at the beginning of May and celebrated with spring flowers and blooms.

Turtle finds lower Altiplano elevation estimate

Thu, 21 Apr 2016 15:38:09 -0400

Fossil turtle fragments found in Bolivia, such as this piece of a shell from a specimen in the genus Chelonoidis, suggest that the elevation of the southern Altiplano was lower 13 million years ago than previously thought. Credit: Darin Croft.

Rare turtle fossils uncovered in Bolivia suggest that, about 13 million years ago, the southern portion of South America’s Altiplano — the arid, high-elevation plateau immediately west of the Andes — was far lower than previously thought.

Mercury levels support volcanic role in end-Cretaceous extinction

Thu, 21 Apr 2016 15:32:54 -0400

In sedimentary rock near Bidart, France, scientists found high levels of mercury associated with the eruption of the massive Deccan Traps flood basalts about 66 million years ago. Credit: Eric Font.

The end-Cretaceous extinction, known for finishing off the last dinosaurs about 66 million years ago, often evokes scenes of a large asteroid hurtling toward Earth. However, new evidence supports a growing consensus that the massive bolide wasn’t the only hazard that life on Earth had to contend with: A prolonged bout of major volcanic eruptions was also spewing climate-altering gases and other emissions such as mercury into the atmosphere.

First all-digital geologic map of Alaska released

Thu, 21 Apr 2016 14:36:16 -0400

The Anchorage area is shown in this portion of the new digital geologic map of Alaska. The full map is available at https://pubs.er.usgs.gov/. Credit: U.S. Geological Survey.

When it comes to natural beauty, Alaska’s rugged, massive landscape is an embarrassment of riches, with towering mountains and lush forests, countless islands and a seemingly endless coastline. Below the surface, it features a wealth of interesting geology and abundant resources. Now, policymakers, land managers, scientists and the public can all explore Alaska a little more deeply with the recent release of the first-ever fully digital geologic map of the entire state.

Reading the ridges: Are climate and the seafloor connected?

Tue, 19 Apr 2016 17:38:41 -0400

New research suggests that the spacing and elevation of abyssal hills at mid-ocean ridges — traditionally thought to form by faulting — could be correlated with past changes in global sea levels. Credit: K. Cantner, AGI.

At the bottom of every ocean basin lies a chain of submarine mountains. Blanketed in black, pillowy basalt, they tower more than a thousand meters above the seafloor and snake for thousands of kilometers. But instead of having a central spine, like a terrestrial mountain range, these mid-ocean ridges have a central trough from hundreds to thousands of meters wide. This is where — in fiery bursts — new oceanic crust is born.

Comment: GAVRT: Learning science by doing science

Tue, 19 Apr 2016 16:04:31 -0400

Students operating the Goldstone Apple Valley Radio Telescope. Credit: GAVRT Program.

Science education is very much a part of the lexicon of K-12 education these days, and numerous STEM (Science, Technology, Engineering and Mathematics) initiatives are underway in schools across the United States. Nonetheless, most students get very little exposure to doing hands-on science, and virtually no exposure to the ways in which scientific research is actually done. The Next Generation Science Standards calls for increased emphasis on observation, analysis and prediction, but currently, most pre-college science education involves memorization of a collection of facts. Emphasis is more often placed on the results of science, not the process for arriving at those results. A partnership among NASA, the Lewis Center for Educational Research (LCER) and the Jet Propulsion Laboratory (JPL) is working to provide one alternative: The Goldstone Apple Valley Radio Telescope Program (GAVRT) — a collaboration in which K-12 students learn about science by doing real science.

Magnesium part of Earth's magnetic field engine

Tue, 19 Apr 2016 15:47:36 -0400

An artist's interpretation of how the precipitation of buoyant magnesium-bearing minerals, which rise toward the core-mantle boundary, from the otherwise iron-rich core could drive compositional convection and help drive Earth's geodynamo. Credit: reprinted from Nature with permission.

Earth’s magnetic field, which arises from convective flows in the planet’s core, known as the geodynamo, has existed for at least 3.4 billion years, meaning that the field-generating processes must have existed for that long as well. But what exactly those processes have looked like throughout Earth’s history, particularly early on, has been poorly understood. In a new study, researchers suggest that magnesium mineral formation in the core is a previously unrecognized but important piece of the puzzle.

Model targets better understanding of recurring Indian-Pacific storm systems

Tue, 19 Apr 2016 15:45:24 -0400

Scientists have known for decades that the Madden-Julian Oscillation (MJO) — a massive gathering of thunderstorms that forms intermittently over the Indian and western Pacific oceans — impacts regional and global weather. Predicting the impacts, however, has been more difficult because relatively little is known about the phenomenon, at least compared to El Niño and some other weather patterns. But in a new study, scientists have devised a mathematical model that clarifies how the MJO develops and progresses, which may pave the way for more accurate predictions of its effects.

Humans evolved early to be more efficient sleepers

Tue, 19 Apr 2016 15:41:39 -0400

Chimpanzees sleep an average of 11.5 hours per day, usually in a tree nest, whereas humans snooze for just seven hours. Credit: Kathelijne Koops, University of Zurich, Switzerland.

We humans spend about a third of our lives asleep. While that might sound like a lot, we require less sleep than most mammals. In a new study, researchers have quantified how much less sleep we need than other primates, and the findings may offer clues to how and when human sleep patterns evolved.

The softer side of hydrothermal vents

Tue, 19 Apr 2016 15:34:36 -0400

A 3-meter-tall talc spire tops the main hydrothermal vent in the Von Damm Vent Field. Credit: National Oceanography Center Southampton.

Seafloor chimneys belching dark plumes of superheated, acidic fluids into the ocean, called “black smokers,” are the most common kind of submarine hydrothermal vent known. But recently scientists discovered a vent system, of a seemingly gentler nature, unlike any observed before.

Fossil leaves provide clues to ancient Australian habitat

Tue, 19 Apr 2016 15:29:35 -0400

Heath and scrubland vegetation cover this part of Stirling Range National Park in southwestern Australia. In the Late Cretaceous, central Australia may have looked similar, with a mosaic of low-growing and open vegetation and woody thickets. Credit: Raymond Carpenter.

Researchers have long thought that the scrublands of Australia developed over the last 25 million to 30 million years as part of a global trend toward colder and drier climates in which rainforests yielded ground to more open, fire-prone environments.

Medieval earthquakes in Nepal may help reveal the region's tectonic future

Tue, 19 Apr 2016 13:38:34 -0400

Scientists found that the sediments underlying Pokhara, in Nepal, which suffered substantial damage from the April 2015 Gorhka earthquake, were deposited by landslides triggered by several medieval-age earthquakes. Credit: Amelie Stolle

The magnitude-7.8 Gorkha earthquake in Nepal in April 2015 triggered landslides and damage that killed more than 8,500 people and injured at least 20,000, including many in and around Pokhara, the country’s second largest city. In a new study, scientists have found evidence that the city — also a major center of tourism in Nepal — and its surroundings sit atop debris from several large medieval-age quakes, confirming that the recent temblor is only the latest in a region with a long history of major earthquakes.

China's Red Deer Cave people may have survived until the last ice age

Mon, 18 Apr 2016 17:41:16 -0400

Artist's reconstruction of a Red Deer Cave man. Credit: Peter Schouten.

In the 1980s, a collection of bones from very small hominids was excavated from a cave in southwestern China, alongside a number of bones from a species of large red deer. Nicknamed the “Red Deer Cave people,” but not yet declared a distinct species, researchers previously dated radiocarbon in the sediments where the bones were found to about 14,000 years ago. In a new comparative study, the same team has now found that the hominids from which the bones came appear to have been similar to — although far smaller than — Homo habilis and Homo erectus, suggesting it could indeed be a new species.

Museums and exhibits in the Dinosaur Diamond

Mon, 18 Apr 2016 17:27:54 -0400

Dinosaur Diamond Map. Credit: Martin Lockley.

Price’s Prehistoric Museum

A mounted skeleton of Utahraptor, the largest-known dromaeosaurid, at the Prehistoric Museum in Price, Utah. Credit: Christine K. Trease.

The Prehistoric Museum in Price, Utah, the western point of the Dinosaur Diamond, now affiliated with Utah State University Eastern, was founded as a tourist attraction in the early 1960s with the acquisition of a complete Allosaurus replica for $2,250. Situated amid the Price-Helper coal mining district, the museum contains many tracks of hadrosaurs and ceratopsians extracted from the coal mines. The museum was expanded in the 1990s and now contains mounted skeletons of Utahraptor and ceratopsians.

Making tracks through the Dinosaur Diamond

Mon, 18 Apr 2016 16:50:47 -0400

Author Martin Lockley beside a Late Triassic trackway formed by an early sauropodomorph. The track was found at the base of the Wingate Sandstone in western Colorado. Credit: Martin Lockley.

For more than a century, the Western Slope of the Rocky Mountains where the mountains descend across the Colorado-Utah border onto the Colorado Plateau has proved a bountiful source of dinosaur fossils. In 1900, the giant Late Jurassic sauropod, Brachiosaurus, was first found in the now world-famous Morrison Formation near Fruita, Colo. Bones in the dinosaur graveyard we now know as Dinosaur National Monument near Vernal, Utah, were discovered starting in 1908 with a Diplodocus femur, followed in 1909 by a nearly complete Apatosaurus and many more dinosaur bones over the ensuing years. These finds — along with multiple others closer to Denver in the late 19th century — set off a fossil-hunting bonanza across the West.

Benchmarks: April 22, 1995: GLOBE is launched

Wed, 13 Apr 2016 18:16:03 -0400

Over the last 20 years, GLOBE students have collected 130 million environmental observations, often without the use of sophisticated instruments. To calculate tree heights (left), students make and use a simple clinometer to measure the angle between the ground and the treetops. To measure clouds (right), students divide the sky into quadrants using their raised arms, then identify cloud types and estimate coverage in each quadrant. Credit: both: courtesy of The Globe Program/All Rights Reserved.

Studying the global environment requires collecting numerous detailed observations. And although it may seem today like we’re awash in such data, relevant observations — collected at the right time and place — are often unavailable. For example, scientists studying precipitation must rely on just a handful of sampling stations: All of the world’s raingages gathered together would only cover an area the size of two basketball courts.

Down to Earth With: Tectonicist Eldridge Moores

Wed, 13 Apr 2016 18:00:05 -0400

Eldridge Moores at the Cordelia Fault, a branch of the San Andreas Fault in the northern Coast Ranges, on a field trip for the general public in March 2010. Credit: Judy Moores.

“When Eldridge Moores was 10 years old, his family lived in Crown King, Ariz., a tiny, remote mining settlement high in the rugged Yavapai Mountains northwest of Phoenix. Money was tight and his family rarely traveled, so Moores vividly remembers a holiday road trip to visit his father’s relatives near San Francisco. The Bay Area left a deep impression on Moores, and, at the end of the journey, upon reaching the first of four switchbacks on the narrow dirt track that led up to Crown King, Moores vehemently pronounced that he would do everything he could to get out of there.

Geologic Column: At the end of the Earth

Wed, 13 Apr 2016 17:25:17 -0400

Tilting at windmills is just as futile these days. credit: ©Shutterstock.com/NCG.

When you think of Spain, what images come to mind? The impoverished sailor from Genoa who was bankrolled by Queen Isabella to sail westward looking for China, but found a New World instead? The conquistadors who used guns, germs, steel and horses to topple two great civilizations? Or (my favorite) a fictional madman called Quixote who tilted at windmills?

Ice (Re)Cap: April 2016

Wed, 13 Apr 2016 17:09:04 -0400

Thawing permafrost in Alaska, which can lead to slope failures like this one along the Noatak River, may increase dramatically this century as air and ground temperatures rise. Credit: Rory Nichols.

From Antarctica to the Arctic; from polar caps, permafrost and glaciers to ocean-rafted sea ice; and from burly bears to cold-loving microbes, fascinating science is found in every nook and crevasse of Earth’s cryosphere, and new findings are announced often. Here are a few of the latest updates.

Comment: How long have humans been altering Earth's climate?

Thu, 07 Apr 2016 18:48:29 -0400

The early anthropogenic hypothesis holds that prolonged warmth in the Holocene was caused by early agriculture. Paleoclimatologists have long sought an analog of the current Holocene interglaciation. Here, precession (A) and obliquity (B), which impact solar insolation, and atmospheric carbon dioxide concentrations (C) of previous interglaciations are compared with the Holocene (stage 1). The closest analog to the Holocene is stage 19, which began about 787,000 years ago. Credit: Ruddiman et al., Review of Geophysics, 2016.

Throughout the 20th century the paleoclimate science community regarded the warmth of the current (Holocene) interglaciation — prior to the major anthropogenic intervention of the last 150 years — as overwhelmingly natural in origin. In this view, changes in Earth’s orbit had resulted in increased summer insolation at high latitudes of the Northern Hemisphere, which began melting the North American and Scandinavian ice sheets 17,000 years ago and eventually ushered in interglacial warmth. Although further orbital shifts then led summer insolation to begin decreasing 10,000 years ago, the drop was thought not to have been substantial enough to cause renewed glaciation.

Bat signals

Fri, 01 Apr 2016 12:34:24 -0400

Mystacina tuberculata foraging on New Zealand's South Island. Credit: Rob Morris.

Bats, the only true-flight mammals, first appeared during the Early Eocene after a period of acute global warming known as the Paleocene-Eocene Thermal Maximum. Despite decades of study, however, much remains unknown about bats. Recent discoveries are shedding new light on the natural history of these creatures, which today comprise one of the most diverse mammalian groups.

Crippling heat stress projected by midcentury in densely populated regions

Fri, 01 Apr 2016 12:28:56 -0400

Land-surface temperatures, as shown in this false-color NASA MODIS image taken on July 1, 2004, were as high as 59 degrees Celsius during a blistering heat wave over the Iberian Peninsula, while "dry-bulb" air temperatures reached up to 40 degrees. New research suggests that many densely populated parts of the planet will be subjected to "crippling" heat stress by midcentury. Credit: NASA Goddard Space Flight Center.

Extreme heat events, defined by the U.S. Environmental Protection Agency as periods of summer weather that are substantially hotter and/or more humid than is typical for a given location and time, can cause heat stress. Heat stress, an illness that occurs when the body is unable to cool itself via sweating, can lead to cramps, heat exhaustion and — at its most severe — heat stroke, a potentially fatal condition.

An absentee note for ancient blueschist: Lack of metamorphic rock does not date onset of plate tectonics

Fri, 01 Apr 2016 12:19:51 -0400

Blueschist (left) and greenschist (right) are both metamorphic rocks that form in subduction zones, but under different thermodynamic conditions. Credit: both: Callan Bentley.

Plate tectonics is a defining characteristic of our 4.5-billion-year-old home planet, responsible for earthquakes, mountain building, and much of the evolution of the planet’s oceans and atmosphere. But when this formative process began is a mystery. Some researchers have pointed to the lack of blueschist — a type of metamorphic rock that only forms in tectonically driven subduction zones — in rocks older than 800 million years as a clue to when subduction began. But a new study rules this option out, offering a novel explanation for the rock’s absence in ancient rocks.

Downgoing plate topography stopped 2005 Sumatra rupture

Fri, 01 Apr 2016 12:10:25 -0400

Earthquakes off the coast of Sumatra in 2004 and 2005 ruptured different neighboring segments of the subduction zone. A raised ridge between the segments may have blocked the ruptures from propagating simultaneously. Credit: K. Cantner, AGI.

In late March 2005, a magnitude-8.7 earthquake struck off the northwest coast of Sumatra, Indonesia, rupturing a portion of the Sunda Megathrust Fault and further terrorizing a region still reeling from the devastating 2004 Boxing Day earthquake and tsunami just three months prior. The March quake, however, could have been far larger than it was, according to new research. Scientists have identified a topographic barrier on the oceanic Indo-Australian Plate — which descends under the Sunda Plate in the Sumatra Subduction Zone — that may have stopped the 2005 rupture from propagating farther.

Inside an icthyosaur's brain

Fri, 01 Apr 2016 12:01:23 -0400

The combination of an unusually well-preserved skull and CT scanning technology has produced the clearest image yet of an ichthyosaur's braincase. Credit: University of Bristol.

While the dinosaurs were busy ruling the continents in the Mesozoic, an order of marine reptiles known as the ichthyosaurs ruled the oceans. Ichthyosaurs are well known from numerous fossils, but they are often found flattened, limiting researchers’ ability to study the skulls and braincases as they existed in life.

Where on Earth? - April 2016

Fri, 01 Apr 2016 09:20:55 -0400

Click to enlarge photo.

Clues for April 2016:

This 85-square-kilometer lake stretches to the northwest of one of Earth’s most active volcanoes, a 1,670-meter-tall andesitic stratovolcano that began forming about 7,000 years ago and most recently erupted in an episode lasting from 1968 to 2010.
The volcano, part of a subduction zone-formed arc, is located in the north of a tropical isthmus nation renowned for its ecotourism. This lake in particular is a popular spot year-round for windsurfing and fishing.
A 157-megawatt hydroelectric dam built in 1979 raised the lake’s surface by more than 40 meters, forcing nearby villages to relocate. Today, the dam provides roughly 10 percent of its home country’s electricity.

North Sea uplift caused Jurassic cooling event

Wed, 30 Mar 2016 19:02:35 -0400

The Laurasian Seaway (a) connected the Boreal Sea to the Tethys Ocean to the south during the Jurassic. Uplift of the North Sea Dome (b) beginning in the Early Jurassic might have blocked the northward flow of warm Tethyan waters through the seaway, causing an abrupt cooling event about 174 million years ago. Credit: Korte et al., Nature Communications, December 2015, CC BY 4.0.

The climate of the Jurassic, long envisioned as ubiquitously warm from the equator to the poles, was actually more dynamic, sometimes cooling dramatically, according to a new study. The research joined isotopic and sedimentological data to suggest that an abrupt cooling event occurred in the midlatitudes early in the Middle Jurassic as a result of changing ocean currents associated with a feature known as the North Sea Dome.

King Oraefajokull

Tue, 29 Mar 2016 20:01:51 -0400

View from Skaftafell National Park toward Öraefajökull Volcano. The toe of the Skaftafellsjökull Glacier and its ice lagoon are to the left. Svínafellsjökull Glacier is to the right. Credit: Tommy Bee.

The Öraefajökull Volcano boasts Iceland’s highest peak — 2,109 meters above sea level — and has the reputation of being Iceland’s largest and most violent volcano. Major eruptions in 1362 and 1727 were among the most explosive in the island’s history, and both were accompanied by catastrophic glacial floods. After the 1362 event, the Icelandic word öraefi, originally meaning “area without a harbor,” was rechristened to mean “wasteland.”

Hekla the heckler

Tue, 29 Mar 2016 19:45:15 -0400

Hekla Volcano overlooking the Thjórsá River. Credit: Hansueli Krapf, CC BY-SA 3.0.

Hekla is one of Iceland’s most active volcanoes, erupting more than 25 times since its first recorded eruption in 1104. The most recent eruptions in 1970, 1980, 1981, 1991 and 2000 have allowed geoscientists to create a detailed eruption profile for the volcano.

Eerily quiet Katla

Tue, 29 Mar 2016 19:38:05 -0400

The largest known jökulhlaups are issued by eruptions of Katla Volcano, which lies under the Mýrdalsjökull Ice Cap. The flow rates of Katla's glacial outburst floods can exceed those of the Amazon River. Credit: Malcom Browne, CC BY-SA 2.0.

Katla Volcano is located near the southern tip of Iceland, under the Mýrdalsjökull Ice Cap. Ashfall deposits found as far away as Norway and Denmark indicate that Katla erupted at least 20 times between A.D. 930 and the last eruption in 1918. Its present dormancy is the longest-known quiet period in the volcano’s history.

Where fire freezes: All eyes, ears and instruments on Iceland's volatile volcanoes

Tue, 29 Mar 2016 18:35:15 -0400

In 1996, Grímsvötn Volcano erupted beneath the Vatnajökull Ice Cap, triggering a massive glacial outburst flood, called a jökulhlaup, that discharged 300,000 cubic meters per second as it flowed across the Skeidarársandur, a glacial outwash plain on the southern coast of Iceland. Credit: USGS/Icelandic Meteorological Office, Oddur Sigurdsson.

With examples of every type of volcano on Earth, and about a third of the island’s more than 30 active volcanic systems buried under glacial ice, Iceland earns its nickname: the land of fire and ice.

Sailors right about sneaky rogue waves

Sun, 27 Mar 2016 16:57:08 -0400

A massive wave, estimated to be more than 18 meters high, hits the starboard side of a tanker heading south from Valdez, Alaska, in the Gulf of Alaska in February 1993. Credit: Captain Roger Wilson, Greenland, N.H., CC BY 2.0.

Sailors are notorious for telling tall tales, including legends about monstrous “rogue waves” that appear at sea without warning. Oceanographers have traditionally dismissed such stories because they thought that unusually large waves would be preceded by series of waves of increasing size.

Lunar atmosphere more active than we thought

Sun, 27 Mar 2016 16:47:00 -0400

NASA's Lunar Atmosphere and Dust Environment Explorer (LADEE) spacecraft orbits near the moon's surface in this illustration. Credit: NASA Ames/Dana Berry

LADEE — pronounced “laddie” and short for Lunar Atmosphere and Dust Environment Explorer — was among the shortest-lived of NASA’s successful satellites. Launched on Sept. 7, 2013, it crashed onto the moon’s surface, as intended, on April 17, 2014, after six months orbiting the moon. Data collected by LADEE have already greatly expanded our understanding of the atmosphere of the moon and other bodies in the solar system; the spacecraft also made a number of unexpected discoveries, some of which were presented at the fall meeting of the American Geophysical Union (AGU) in San Francisco last December.

Going with the flow: Mapping the mantle under the Cascadia Subduction Zone

Tue, 22 Mar 2016 19:44:36 -0400

A new study using seafloor seismic instruments has revealed more information about the complex and dangerous Cascadia Subduction Zone. Credit: K. Cantner, AGI.

The Cascadia Subduction Zone (CSZ), off the Pacific Northwest coast of the United States and Canada, is one of the world’s most mysterious — and potentially dangerous — earthquake zones. Eerily quiet since a massive magnitude-9 event in 1700, scientists have long warned that the 1,000-kilometer-long fault zone could produce another devastating earthquake and tsunami. Now, a new effort to map the fault zone’s tectonic environment, including the underlying mantle, is shedding light on some of the dynamic forces that may influence earthquakes in the region.

Underground ants can't take the heat

Tue, 22 Mar 2016 19:11:07 -0400

According to a recent study, underground species of army ants are much less tolerant of high temperatures than aboveground ants. Credit: Kaitlin Baudier.

Army ants, which move in swarms and show their prey little mercy, are some of the most ferocious insects in the animal kingdom, but a recent study reveals a weakness in some underground species: warm temperatures.

A long layover on the Bering land bridge

Wed, 16 Mar 2016 20:22:15 -0400

The Late Pleistocene remains of two infants recovered from the Upper Sun River campsite in eastern Alaska are shedding light on the peopling of the Americas. Credit: K. Cantner, AGI, after Tackney, et al. 2015.

About 11,500 years ago, two infants were laid to rest side by side in a shallow grave 80 kilometers southeast of what is now Fairbanks, Alaska. The area was once part of Beringia, a strip of ice-free land connected to Asia during the last ice age. Researchers found the remains in 2013, and have now sequenced the complete mitochondrial genomes of the two children. The results revealed that the infants had different mothers and that their genetic signatures are found today throughout North and South America.

Getting there and getting around Gotland

Wed, 16 Mar 2016 20:12:25 -0400

Wildflowers blooming near the Gotland coast. Credit: Naomi Lubick.

Useful websites for planning your trip to Gotland include the island’s own commercial sites: Gotland.com and Destination Gotland. Start there for everything from travel to entertainment events, and for ideas on what to see.

Travels in Geology: Gotland getaway: Sweden's 'tropical' escape in the Baltic

Wed, 16 Mar 2016 19:46:07 -0400

The iconic sea stacks, called raukarna, of Langhammars Nature Reserve on Fårö Island are the remnants of Silurian coral reefs. Credit: Naomi Lubick.

White sand beaches and thatched-roof houses probably are not part of most people’s conception of Sweden, yet they are characteristic of this northern European nation’s very own coral reef island getaway. This is no tropical island, mind you: 3,100-plus-square-kilometer Gotland sits squarely in the Baltic Sea, off the southeastern shore of Sweden just a short trip from the capital, Stockholm. My husband and I had heard about Gotland since we moved to Sweden several years ago. Swedes extol their country’s largest island as a place with good food, great beaches and lovely summers.

Mass measured for smallest exoplanet yet

Wed, 16 Mar 2016 19:01:16 -0400

This illustration depicts the Kepler-138 system, with Mars-like Kepler-138b in the foreground. The masses and densities of the system's three small planets were determined by studying how each affected the orbits of the other two. Credit: Danielle Futselaar, SETI.

By the late 19th century, astronomers had calculated correctly that Mars — about half the diameter of Earth — holds roughly one-tenth the mass of Earth, whereas its density is about 71 percent that of our planet. These fundamental planetary traits have also long been known for Mercury and Venus. But measuring the masses and densities of the many roughly Earth-sized exoplanets discovered lately — which, to space telescopes, appear as mere specks as they pass in front of, or transit, their home stars — has proved challenging.

The ups and downs of an island

Wed, 16 Mar 2016 18:54:42 -0400

The approximate amount of uplift of Chile's Isla Santa Mariá resulting from the 2010 Maule earthquake is evident here from the ring of dead seaweed near the base of the rock. Credit: Daniel Melnick.

In 1835, Captain Robert FitzRoy and the crew of the HMS Beagle — who were exploring and studying the Chilean coast with Charles Darwin in tow — arrived at Isla Santa Mariá near the city of Concepción six weeks after a magnitude-8.5 earthquake jolted the region. Along with scenes of dried seaweed and dead mussels lining the island’s shores well above the high-tide line, comparison of a bathymetric survey of a shallow bay adjacent to Santa Mariá to one conducted the previous year suggested to FitzRoy that the earthquake had thrust the island 2.4 to 3 meters out of the water.

Protracted drought threatens California levees

Tue, 15 Mar 2016 20:52:29 -0400

An earthen levee along the Sacramento River in California. Credit: public domain.

Levee failures are most often associated with the onslaught of water from large storms, such as Hurricane Katrina, whose landfall in 2005 caused more than 50 floodwalls and levees around New Orleans to fail.

Rainbows reclassified

Mon, 21 Dec 2015 19:08:35 -0500

A rainbow in Toulouse, France, after a storm. Credit: Jean Ricard

Rainbows — those arches of color that streak across wet skies — are recognizable to almost everyone. Our understanding of rainbows, though, particularly how they form and the diversity of shapes they can take, is still fuzzy.