The Cassini spacecraft has captured the closest ever view of Saturn's small, 'wavemaker,' moon, Daphnis, allowing astronomers to observe new details up close.

The image is the latest in a series of spectacular pictures of Saturn's rings and moons sent back by the spacecraft.

Daphnis is about five miles (8 kilometres) in diameter and orbits Saturn in the 26-mile (42-kilometer) wide Keeler Gap within the A ring - the outermost of the large bright rings.

In this image, taken by the Cassini narrow-angle camera, however, the gap appears smaller due to the spacecraft's viewing angle.

A new study published in the peer-reviewed journal Space Weather reports the discovery of radiation "clouds" at aviation altitudes. When airplanes fly through these clouds, dose rates of cosmic radiation normally absorbed by air travelers can double or more.

"We have flown radiation sensors onboard 264 research flights at altitudes as high as 17.3 km (56,700 ft) from 2013 to 2017," says Kent Tobiska, lead author of the paper and PI of the NASA-supported program Automated Radiation Measurements for Aerospace Safety (ARMAS). "On at least six occasions, our sensors have recorded surges in ionizing radiation that we interpret as analogous to localized clouds."

The fact that air travelers absorb radiation is not news. Researchers have long known that cosmic rays crashing into Earth's atmosphere create a spray of secondary particles such as neutrons, protons, electrons, X-rays and gamma-rays that penetrate aircraft. 100,000 mile frequent flyers absorb as much radiation as 20 chest X-rays—and even a single flight across the USA can expose a traveler to more radiation than a dental X-ray.

Conventional wisdom says that dose rates should vary smoothly with latitude and longitude and the height of the aircraft. Any changes as a plane navigates airspace should be gradual. Tobiska and colleagues have found something quite different, however: Sometimes dose rates skyrocket for no apparent reason.

"We were quite surprised to see this," says Tobiska.

A pair of researchers affiliated with the Natural History Museum in Chemnitz and Technische Universität Bergakademie Freiberg, both in Germany, has found evidence in ancient tree rings of a solar sunspot cycle millions of years ago similar to the one observed in more modern times. In their paper published in the journal Geology, Ludwig Luthardt and Ronny Rößler describe how they gathered an assortment of petrified tree samples from a region in Germany and used them to count sunspot cycles.

Scientists know that the sun undergoes a sunspot cycle of approximately 11 years—some spots appear, grow cooler and then slowly move toward the equator and eventually disappear—the changes to the sun spots cause changes to the brightness level of the sun—as the level waxes and wanes, plants here on Earth respond, growing more or less in a given year—this can be seen in the width of tree rings. In this new effort, the researchers gathered petrified tree samples from a region of Germany that was covered by lava during a volcanic eruption approximately 290 million years ago (during the Permian period), offering a historical record of sun activity.

The research pair obtained 43 petrified tree specimens (tree-trunk slices) and report that they were able to count 1,917 rings which were preserved well enough to allow for observation under a microscope. Because the trees had all died at the same time, the researchers were able to establish a baseline between them which allowed for comparing tree ring growth between samples over the same time periods—which covered 79 years. Doing so, they report, revealed very clearly a cycle of growth similar to that seen in modern trees, though in this case, it was slightly different. Today the cycle is an average of 11.2 years, back then it was 10.6—close enough, the researchers suggest, to conclude that the sun has been behaving very predictably for at least 290 million years.

It should be noted that not everyone agrees with the theory that sunspot activity leaves such a clear record in tree rings—other factors might be involved such as general global temperature, weather patterns or even outbreaks of insect populations.

More information: Ludwig Luthardt et al. Fossil forest reveals sunspot activity in the early Permian, Geology(2017)

Perceived existential threats posed to humanity by artificial intelligence (AI) are "uninformed," a US Department of Defense report has concluded - although some still harbor grave reservations about the technology's potential.

Perspectives on Research in Artificial Intelligence and Artificial General Intelligence Relevant to DoD, authored by a group of independent scientists belonging to JASON, the secretive organization that counsels the US government on sensitive scientific matters, states growing public suspicion of AI is "not always based on fact," especially in respect of military technologies.

Noting that in January 2015 Elon Musk, founder of space transport services company SpaceX and chief product architect at Tesla Motors, declared AI the "biggest existential threat" to the survival of the human race, the report suggests alleged hazards do not cohere with the current research directions of AI. Instead, they "spring from dire predictions about one small area of research within AI, Artificial General Intelligence."

AGI relates to the development of machines capable of long-term decision-making and intent, akin to real human beings.

Humans, not climate changes as it was previously assumed, caused the extinction of the giant beasts that once roamed Australia, a new study proves.

Prehistoric Australian megafauna included 1,000-pound kangaroos, 2-ton wombats, 25-foot-long lizards, 400-pound flightless birds, 300-pound marsupial lions and Volkswagen-sized tortoises. But some 50,000 years ago, more than 85 percent of Australia's animals weighing over 100 pounds went extinct for reasons that have become a subject of much scientific debate.

A team of researchers from Monash University in Victoria, Australia and the University of Colorado Boulder tried to reconstruct the past climate and ecosystems of the continent. They studied sediment core which is drilled in the Indian Ocean off the Australian coast, and analyzed chronological layers of material blown and washed into the ocean.

The study was published in Nature Communications on January 20.

Unlike mythical vampires, vampire bats do not prey on humans — or do they? Scientists have found the first evidence of vampire bats supping on human blood.

Diphylla ecaudata, also known as the hairy-legged vampire bat, inhabits forests in northeastern Brazil and is one of three species of vampire bats that feed only on blood. It was thought that birds were its sole prey, but dung analysis recently revealed that other types of two-legged animals — humans — were on the bat's bill of fare.

The bats' feeding preferences may have shifted because birds were hard to find, hinting that even highly specialized bats could have more flexibility in their diets than expected, the study authors wrote.

Rainfall patterns in the Sahara during the 6,000-year "Green Sahara" period have been pinpointed by analyzing marine sediments, according to new research.

What is now the Sahara Desert was the home to hunter-gatherers who made their living off the animals and plants that lived in the region's savannahs and wooded grasslands 5,000 to 11,000 years ago.

"It was 10 times as wet as today," said lead author Jessica Tierney of the University of Arizona. Annual rainfall in the Sahara now ranges from about 4 inches to less than 1 inch (100 to 35 mm).

Although other research had already identified the existence of the Green Sahara period, Tierney and her colleagues are the first to compile a continuous record of the region's rainfall going 25,000 years into the past.

The team's paper "Rainfall regimes of the Green Sahara," is scheduled for publication in the journal Science Advances on Jan. 18.

Archaeological evidence shows humans occupied much of the Sahara during the wet period, but left for about a thousand years around 8,000 years ago—the middle of the Green Sahara period.

Other investigators have suggested the Sahara became drier at the time people left, but the evidence was not conclusive, said Tierney, a UA associate professor of geosciences.

Her team's continuous rainfall record shows a thousand-year period about 8,000 years ago when the Sahara became drier. That drier period coincides with when people left, she said.

"It looks like this thousand-year dry period caused people to leave," Tierney said.

"What's interesting is the people who came back after the dry period were different—most raised cattle. That dry period separates two different cultures. Our record provides a climate context for this change in occupation and lifestyle in the western Sahara."

The world's first quantum communication satellite is now officially operational following months of in-orbit testing, the Chinese Academy of Sciences (CAS) announced, saying that performance of the device is "much better" than was initially expected.

The 600+kg Quantum Experiments at Space Scale (QUESS), nicknamed Micius after the ancient Chinese philosopher and scientist, was sent into orbit by China in August, in a bid to develop "hack-proof" communications in an age of ever-increasing cyber espionage.

Following the satellite's deployment into orbit in August for its two-year mission, Chinese scientists spent much time testing the satellite systems and its links back to Earth, CAS said.

A popular blog that lists "potential, possible, or probable predatory" publishers and journals has disappeared, but it is not clear why.

The blog—started in 2010 by librarian Jeffrey Beall of the University of Colorado in Denver (CU Denver)—now states: "This service is no longer is available."

Beall declined to comment. But a CU Denver spokesperson told Science Insider that Beall made a "personal decision" to take down his list of low-quality journals that charge authors a fee to publish, often with little or no review or editing. The spokesperson says the blog was not hacked, nor was it taken down as a result of legal threats, and Beall will remain on the school's faculty. The spokesperson could not confirm whether the blog's removal is permanent.

"I'm surprised and concerned," says pseudonymous science blogger Neuroskeptic. "Beall's list is (was?) extremely valuable because predatory journals are a huge problem."

Some are circulating a cached version of Beall's list on Twitter. Others speculated on social media that the shutdown may have something to do with the transfer of its lists to the company Cabell's International in Beaumont, Texas. But the firm has publicly said it is in "no way involved" with the blog's closure. Nevertheless, Cabell's noted that it has been developing its own blacklist, working with Beall as a consultant, since 2015, and plans to launch it later this year.

Lacey Earle, vice president of business development at Cabell's International, tweeted that Beall "was forced to shut down blog due to threats & politics."

An artificial intelligence headset that records brain waves, links them to the individual's moods, and then composes original music to uplift its user's feelings has been invented.

The device, developed by a team of Japanese scientists from Osaka University and Tokyo City University and a research institute in Belgium, was unveiled on January 16, Japanese newspaper Asahi reported.

To design the headset the scientists recorded the brain waves of volunteers while they listened to different music samples ranging from J-Pop to nursery rhymes. Based on this data, they create a personalized "emotional music model" for each individual. The AI first studied the relations between the music and the emotions of a particular person and then writes the ideal musical composition.

The story reminds of the famous quotation from the movie "I, Robot" and makes us think again in what unexpected way computers might become better than us.