Scientists track the brain-skull transition from dinosaurs to birds

These are CT scan images of the skull roof (front bone in pink, parietal in green) and brain (in blue) of, top to bottom, a chicken, the birdlike dinosaur Zanabazar, the primitive dinosaur Herrerasaurus, and Proterosuchus, an ancestral form that diverged before the bird/crocodile split.

The dramatic, dinosaur-to-bird transition that occurred in reptiles millions of years ago was accompanied by profound changes in the skull roof of those animals -- and holds important clues about the way the skull forms in response to changes in the brain -- according to a new study.

It is the first time scientists have tracked the link between the brain's development and the roofing bones of the skull. The findings appear in the Sept. 11 edition of the journal Nature Ecology and Evolution.

"Across the dinosaur-bird transition, the skull transforms enormously and the brain enlarges. We were surprised that no one had directly addressed the idea that the underlying parts of the brain -- the forebrain and midbrain -- are correlated or somehow developmentally related to the overlying frontal and parietal bones," said co-senior author Bhart-Anjan Singh Bhullar, an assistant professor of geology and geophysics at Yale University and assistant curator of vertebrate paleontology and vertebrate zoology at the Yale Peabody Museum of Natural History.

Matteo Fabbri, a graduate student in Bhullar's lab, is the first author of the study.

Although previous studies have shown a general relationship between the brain and skull, associations between specific regions of the brain and individual elements of the skull roof have remained unclear. This has led to conflicting theories on some aspects of skull development.

Bhullar and his colleagues set out to trace the evolution of brain and skull shape not simply in the dinosaurs closest to birds, but in the entire lineage leading from reptiles to birds. They discovered that most reptile brains and skulls were markedly similar to each other. It was the dinosaurs most closely related to birds, as well as birds themselves, that were divergent, with enlarged brains and skulls ballooning out around them.

"We found a clear relationship between the frontal bones and forebrain and the parietal bones and midbrain," Bhullar said. The researchers confirmed this finding by looking at embryos of lizards, alligators, and birds using a new contrast-stained CT scanning technique.

"We suggest that this relationship is found across all vertebrates with bony skulls and indicates a deep developmental relationship between the brain and the skull roof," Bhullar said. "What this implies is that the brain produces molecular signals that instruct the skeleton to form around it, although we understand relatively little about the precise nature of that patterning."

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Are we being watched? Tens of other worlds could spot the Earth

Image showing where transits of our solar system planets can be observed. Each line represents where one of the planets could be seen to transit, with the blue line representing Earth; an observer located here could detect us.

A group of scientists from Queen's University Belfast and the Max Planck Institute for Solar System Research in Germany have turned exoplanet-hunting on its head, in a study that instead looks at how an alien observer might be able to detect Earth using our own methods. They find that at least nine exoplanets are ideally placed to observe transits of Earth, in a new work published in the journal Monthly Notices of the Royal Astronomical Society.

Thanks to facilities and missions such as SuperWASP and Kepler, we have now discovered thousands of planets orbiting stars other than our Sun, worlds known as 'exoplanets'. The vast majority of these are found when the planets cross in front of their host stars in what are known as 'transits', which allow astronomers to see light from the host star dim slightly at regular intervals every time the planet passes between us and the distant star.

In the new study, the authors reverse this concept and ask, "How would an alien observer see the Solar System?" They identified parts of the distant sky from where various planets in our Solar System could be seen to pass in front of the Sun -- so-called 'transit zones' -- concluding that the terrestrial planets (Mercury, Venus, Earth, and Mars) are actually much more likely to be spotted than the more distant 'Jovian' planets (Jupiter, Saturn, Uranus, and Neptune), despite their much larger size.

"Larger planets would naturally block out more light as they pass in front of their star," commented lead author Robert Wells, a PhD student at Queen's University Belfast. "However the more important factor is actually how close the planet is to its parent star -- since the terrestrial planets are much closer to the Sun than the gas giants, they'll be more likely to be seen in transit."

To look for worlds where civilisations would have the best chance of spotting our Solar System, the astronomers looked for parts of the sky from which more than one planet could be seen crossing the face of the Sun. They found that three planets at most could be observed from anywhere outside of the Solar System, and that not all combinations of three planets are possible.

Katja Poppenhaeger, a co-author of the study, adds, "We estimate that a randomly positioned observer would have roughly a 1 in 40 chance of observing at least one planet. The probability of detecting at least two planets would be about ten times lower, and to detect three would be a further ten times smaller than this."

Of the thousands of known exoplanets, the team identified sixty-eight worlds where observers would see one or more of the planets in our Solar System transit the Sun. Nine of these planets are ideally placed to observe transits of Earth, although none of the worlds are deemed to be habitable.

In addition, the team estimate that there should be approximately ten (currently undiscovered) worlds which are favourably located to detect the Earth and are capable of sustaining life as we know it. To date however, no habitable planets have been discovered from which a civilisation could detect the Earth with our current level of technology.

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Liar, liar, pants on fire! Groups lie more than individuals, according to new research

Do you pride yourself on being an honest person? Even individuals who have a proven track record of honest behavior are no match for the potentially negative influences present in a group dynamic, especially when money is at stake, according to a new study, published in the INFORMS journal Management Science.

When organizations are exposed for large-scale deceptive or corrupt behavior, often it is not the actions of one or two employees, but a coordinated effort of many individuals, to include upper level management. Prominent examples include the bankruptcies of WorldCom and Enron, and even more recently, the alleged issuance of faulty emissions certificates by German car manufacturer Volkswagen. The study, "I lie? We lie! Why? Experimental Evidence on a Dishonesty Shift in Groups," explored what motivates a group of people, especially those who previously behaved honestly, to work together to deceive.

The study authors, Martin G. Kocher, Simeon Schudy and Lisa Spantig, all of the Ludwig-Maximilians-University of Munich, studied 273 participants in both individual and group situations. Participants, who were paid for their role in the study, were shown video of dice rolls and asked to report the number shown on the die. The higher the reported die roll, the larger the monetary compensation. Participants were evaluated on an individual basis, and in two group settings: one in which all members of the group must report the same die roll to receive a payoff, and another in which members do not have to report the same die roll to receive a payoff. In the group settings, members are able to communicate with each other via a chat feature.

"We observed that groups lie significantly more than individuals when group members face mutual financial gain and have to coordinate an action in order to realize that financial gain," said Kocher.

Of the 78 groups that participated in the study, arguments for dishonesty were explicitly mentioned in 51 percent of the group chats. In fact, of the messages that were exchanged among group members, 43.4 percent argued for dishonest reporting, while only 15.6 percent consisted of arguments for honesty. Interestingly, the authors found that the number of individuals in each group who had exhibited dishonest behavior in the individual portion of the study had no real impact on these results, as dishonesty occurred even in groups where all members had previously responded honestly.

"The ability for group members to exchange and discuss potential justifications for their dishonest behavior can create an overall shift in the group's beliefs of what constitutes moral behavior," said Spantig. "This allows them to establish a new norm regarding what does or does not constitute dishonest behavior," according to Schudy.

From Science Daily

3-D-printed biomaterials that degrade on demand

Brown researchers have found a way to 3-D print intricate temporary microstructures that can be degraded on demand using a biocompatible chemical trigger. The technique could be useful could be useful in fabricating microfluidic devices, creating biomaterials that respond dynamically to stimuli and in patterning artificial tissue.

Brown University engineers have demonstrated a technique for making 3-D-printed biomaterials that can degrade on demand, which can be useful in making intricately patterned microfluidic devices or in making cell cultures than can change dynamically during experiments.

"It's a bit like Legos," said Ian Wong, an assistant professor in Brown's School of Engineering and co-author of the research. "We can attach polymers together to build 3-D structures, and then gently detach them again under biocompatible conditions."

The research is published in the journal Lab on a Chip.

The Brown team made their new degradable structures using a type of 3-D printing called stereolithography. The technique uses an ultraviolet laser controlled by a computer-aided design system to trace patterns across the surface of a photoactive polymer solution. The light causes the polymers to link together, forming solid 3-D structures from the solution. The tracing process is repeated until an entire object is built from the bottom up.

Stereolithographic printing usually uses photoactive polymers that link together with covalent bonds, which are strong but irreversible. For this new study, Wong and his colleagues wanted to try creating structures with potentially reversible ionic bonds, which had never been done before using light-based 3-D printing. To do it, the researchers made precursor solutions with sodium alginate, a compound derived from seaweed that is known to be capable of ionic crosslinking.

"The idea is that the attachments between polymers should come apart when the ions are removed, which we can do by adding a chelating agent that grabs all the ions," Wong said. "This way we can pattern transient structures that dissolve away when we want them to."

The researchers showed that alginate could indeed be used in stereolithography. And by using different combinations of ionic salts -- magnesium, barium and calcium -- they could create structures with varying stiffness, which could then be dissolved away at varying rates.

The research also showed several ways in such temporary alginate structures could be useful.

"It's a helpful tool for fabrication," said Thomas M. Valentin, a Ph.D. student in Wong's lab at Brown and the study's lead author. The researchers showed that they could use alginate as a template for making lab-on-a-chip devices with complex microfluidic channels.

"We can print the shape of the channel using alginate, then print a permanent structure around it using a second biomaterial," Valentin said. "Then we simply dissolve away the alginate and we have a hollow channel. We don't have to do any cutting or complex assembly."

The researchers also showed that degradable alginate structures are useful for making dynamic environments for experiments with live cells. They performed a series of experiments with alginate barriers surrounded by human mammary cells, observing how the cells migrate when the barrier is dissolved away. These kinds of experiments can be useful in investigating wound-healing processes or the migration of cells in cancer.

The experiments showed that neither the alginate barrier nor the chelating agent used to dissolve it away had any appreciable toxicity to the cells. That suggests that degradable alginate barriers are a promising option for such experiments.

The biocompatibility of the alginate is promising for additional future applications, including in making scaffolds for artificial tissue and organs, the researchers say.

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Crab nebula in the limelight: Unified model for the entire radiation spectrum

This composite image of the Crab Nebula was assembled with arbitrary colour scaling by combining data from five telescopes spanning nearly the entire electromagnetic spectrum: the radio emission representing the wind of charged particles from the central neutron star in red (from the Karl G. Jansky Very Large Array), the infrared including the glow of dust particles absorbing ultraviolet and visible light in yellow (from the Spitzer Space Telescope), the visible-light image featuring the hot filamentary structures in green (from the Hubble Space Telescope), the ultraviolet image in blue and the X-ray image in purple showing the effect of an energetic cloud of electrons (from the XMM-Newton Observatory and the Chandra X-ray Observatory).

The origin of cosmic rays, high-energy particles from outer space constantly impacting on Earth, is among the most challenging open questions in astrophysics. Now new research published in the journal Monthly Notices of the Royal Astronomical Society sheds new light on the origin of those energetic particles.

Discovered more than a hundred years ago and considered a potential health risk to airplane crews and astronauts, cosmic rays are believed to be produced by shock waves, for example those resulting from supernova explosions. The most energetic cosmic rays streaking across the universe carry 10 to 100 million times the energy generated by particle colliders such as the Large Hadron Collider at CERN.

The Crab nebula, the remnant of a supernova explosion that was observed almost a thousand years ago in AD1054, is one of the best studied objects in the history of astronomy and a known source of cosmic rays. It emits radiation across the entire electromagnetic spectrum, from gamma rays, ultraviolet and visible light, to infrared and radio waves. Most of what we see comes from very energetic particles (electrons), and astrophysicists can construct detailed models to try to reproduce the radiation that these particles emit.

The new study, by Federico Fraschetti at the University of Arizona, USA, and Martin Pohl at the University of Potsdam, Germany, reveals that the electromagnetic radiation streaming from the Crab nebula may originate in a different way than scientists have traditionally thought: the entire zoo of radiation can potentially be unified and arise from a single population of electrons, a hypothesis which was previously deemed impossible.

According to the generally accepted model, once the particles reach a shock boundary, they bounce back and forth many times due to the magnetic turbulence. During this process they gain energy -- in a similar way to a tennis ball being bounced between two rackets that are steadily moving nearer to one other -- and are pushed closer and closer to the speed of light. Such a model follows an idea introduced by the Italian physicist Enrico Fermi in 1949.

"The current models do not include what happens when the particles reach their highest energy," said Federico, a staff scientist at the University of Arizona's Departments of Planetary Sciences, Astronomy and Physics. "Only if we include a different process of acceleration, in which the number of higher energy particles decreases faster than at lower energy, can we explain the entire electromagnetic spectrum we see. This tells us that while the shock wave is the source of the acceleration of the particles, the mechanisms must be different."

Co-author Martin Pohl added: "The new result represents an important advance for our understanding of particle acceleration in cosmic objects, and helps to decipher the origin of the energetic particles that are found almost everywhere in the universe."

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Monkey sees ... monkey knows?

University of Rochester researchers Jessica Cantlon and Stephen Ferrigno determined that non-human primates exhibited metacognitive illusions after they observed primates completing these series of steps on a computer.

Socrates is often quoted as having said, "I know that I know nothing." This ability to know what you know or don't know -- and how confident you are in what you think you know -- is called metacognition.

When asked a question, a human being can decline to answer if he knows that he does not know the answer. Although non-human animals cannot verbally declare any sort of metacognitive judgments, Jessica Cantlon, an assistant professor of brain and cognitive sciences at Rochester, and PhD candidate Stephen Ferrigno, have found that non-human primates exhibit a metacognitive process similar to humans. Their research on metacognition is part of a larger enterprise of figuring out whether non-human animals are "conscious" in the human sense.

In a paper published in Proceedings for the Royal Society B, they report that monkeys, like humans, base their metacognitive confidence level on fluency -- how easy something is to see, hear, or perceive. For example, humans are more confident that something is correct, trustworthy, or memorable -- even if this may not be the case -- if it is written in a larger font.

"Humans have a variety of these metacognitive illusions -- false beliefs about how they learn or remember best," Cantlon says.

Because other primate species exhibit metacognitive illusions like humans do, the researchers believe this cognitive ability could have an evolutionary basis. Cognitive abilities that have an evolutionary basis are likely to emerge early in development.

"Studying metacognition in non-human primates could give us a foothold for how to study metacognition in young children," Cantlon says. "Understanding the most basic and primitive forms of metacognition is important for predicting the circumstances that lead to good versus poor learning in human children."

Cantlon and Ferrigno determined that non-human primates exhibited metacognitive illusions after they observed primates completing a series of steps on a computer.

The monkey touches a start screen.

He sees a picture, which is the sample. The goal is to remember that sample because he will be tested on this later. The monkey touches the sample to move to the next screen.

The next screen shows the sample picture among some distractors. The monkey must touch the image he has seen before.

Instead of getting a reward right away -- to eliminate decisions based purely on response-reward -- the monkey next sees a betting screen to communicate how certain he is that he's right. If he chooses a high bet and is correct, three tokens are added to a token bank. Once the token bank is full, the monkey gets a treat. If he gets the task incorrect and placed a high bet, he loses three tokens. If he placed a low bet, he gets one token regardless if he is right or wrong.

Researchers manipulated the fluency of the images, first making them easier to see by increasing the contrast (the black image), then making them less fluent by decreasing the contrast (the grey image).

The monkeys were more likely to place a high bet, meaning they were more confident that they knew the answer, when the contrast of the images was increased.

"Fluency doesn't affect actual memory performance," Ferrigno says. "The monkeys are just as likely to get an answer right or wrong. But this does influence how confident they are in their response."

Since metacognition can be incorrect through metacognitive illusion, why then have humans retained this ability?

"Metacognition is a quick way of making a judgment about whether or not you know an answer," Ferrigno says. "We show that you can exploit and manipulate metacognition, but, in the real world, these cues are actually pretty good most of the time."

Take the game of Jeopardy, for example. People press the buzzer more quickly than they could possibly arrive at an answer. Higher fluency cues, such as shorter, more common, and easier-to-pronounce words, allow the mind to make snap judgments about whether or not it thinks it knows the answer, even though it's too quick for it to actually know.

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Nutrition has benefits for brain network organization

An assortment of foods containing omega 3 healthy fats acids.

Nutrition has been linked to cognitive performance, but researchers have not pinpointed what underlies the connection. A new study by University of Illinois researchers found that monounsaturated fatty acids -- a class of nutrients found in olive oils, nuts and avocados -- are linked to general intelligence, and that this relationship is driven by the correlation between MUFAs and the organization of the brain's attention network.

The study of 99 healthy older adults, recruited through Carle Foundation Hospital in Urbana, compared patterns of fatty acid nutrients found in blood samples, functional MRI data that measured the efficiency of brain networks, and results of a general intelligence test. The study was published in the journal NeuroImage.

"Our goal is to understand how nutrition might be used to support cognitive performance and to study the ways in which nutrition may influence the functional organization of the human brain," said study leader Aron Barbey, a professor of psychology. "This is important because if we want to develop nutritional interventions that are effective at enhancing cognitive performance, we need to understand the ways that these nutrients influence brain function."

"In this study, we examined the relationship between groups of fatty acids and brain networks that underlie general intelligence. In doing so, we sought to understand if brain network organization mediated the relationship between fatty acids and general intelligence," said Marta Zamroziewicz, a recent Ph.D. graduate of the neuroscience program at Illinois and lead author of the study.

Studies suggesting cognitive benefits of the Mediterranean diet, which is rich in MUFAs, inspired the researchers to focus on this group of fatty acids. They examined nutrients in participants' blood and found that the fatty acids clustered into two patterns: saturated fatty acids and MUFAs.

"Historically, the approach has been to focus on individual nutrients. But we know that dietary intake doesn't depend on any one specific nutrient; rather, it reflects broader dietary patterns," said Barbey, who also is affiliated with the Beckman Institute for Advanced Science and Technology at Illinois.

The researchers found that general intelligence was associated with the brain's dorsal attention network, which plays a central role in attention-demanding tasks and everyday problem solving. In particular, the researchers found that general intelligence was associated with how efficiently the dorsal attention network is functionally organized used a measure called small-world propensity, which describes how well the neural network is connected within locally clustered regions as well as across globally integrated systems.

In turn, they found that those with higher levels of MUFAs in their blood had greater small-world propensity in their dorsal attention network. Taken together with an observed correlation between higher levels of MUFAs and greater general intelligence, these findings suggest a pathway by which MUFAs affect cognition.

"Our findings provide novel evidence that MUFAs are related to a very specific brain network, the dorsal attentional network, and how optimal this network is functionally organized," Barbey said. "Our results suggest that if we want to understand the relationship between MUFAs and general intelligence, we need to take the dorsal attention network into account. It's part of the underlying mechanism that contributes to their relationship."

Barbey hopes these findings will guide further research into how nutrition affects cognition and intelligence. In particular, the next step is to run an interventional study over time to see whether long-term MUFA intake influences brain network organization and intelligence.

Read more at Science Daily

The Number of Monarch Butterflies in Western North America Is Plummeting

A Monarch butterfly is viewed in a forest of eucalyptus trees at the Goleta Butterfly Preserve on February 10, 2015, in Goleta, California.

Up until the 1980s, around 10 million monarch butterflies spent their winters in coastal California. Their arrival in places like Pacific Grove, aka Butterfly Town USA, was admired by locals and visitors eager to witness these beautiful, delicate insects and their distinctive orange wings.

While Butterfly Town USA still has its renowned monarch butterfly sanctuary, this and other places across western North America have seen numbers of the pollinating insects plummet.

“Today there are barely 300,000,” said Cheryl Schultz, an associate professor of Washington State University, Vancouver.

She and her colleagues arrived at that estimate after combining data from hundreds of volunteers who have participated in the Xerces Society for Invertebrate Conservation’s Western Monarch Thanksgiving Count since 1997, with earlier monarch counts conducted by amateur and professional butterfly enthusiasts in the 1980s and 1990s. The findings are published in the journal Biological Conservation.

Western monarchs form a distinct population segment from eastern monarchs, much like the relationship between different runs of salmon in the Pacific Northwest. Western monarchs intermix with eastern monarchs from time to time, but are not a different species or subspecies.

Like eastern monarchs, which overwinter in Mexico, western monarchs have an impressive and lengthy migration. They spend the winter months in forested groves along coastal California before fanning out in the spring to lay their eggs on milkweed and consume nectar from flowers in Arizona, California, Nevada, Oregon, Washington, Idaho, and Utah. They then return to their coastal overwintering sites in the fall.

A new study finds monarch butterfly populations from western North America have declined far more dramatically than was previously known and face a greater risk of extinction than eastern monarchs.

In a second paper, Sarina Jepsen, endangered species program director at Xerces, and her team list the top 25 highest priority overwintering sites for conservation.

“Among the sites with the most severe population drops are Lighthouse Field and Natural Bridges, which are both in Santa Cruz,” Jepsen said. “However, Santa Cruz is in the core of the overwintering range, and as the population has gotten smaller, many of the peripheral sites in the San Diego area and north of San Francisco no longer host monarchs in the winter.”

Schultz’s colleague Elizabeth Crone, a professor of biology at Tufts University, said some conservation biologists mistakenly assume monarch butterflies are in decline primarily because the insects cannot find enough places to lay their eggs. Instead, research indicates multiple factors could be causing the decline. Drought severity may be one, along with loss of milkweed-rich grasslands throughout the West, and particularly in California’s Central Valley.

“We also know that the use of many insecticides and herbicides have increased dramatically in the past couple of decades in some parts of the West that monarchs use,” Jepsen said. “We have documented the loss of dozens of monarch overwintering sites along coastal California, as housing developments replace forested habitat, and dozens more sites have been degraded.”

Some environmentalists suspect that increased use of glyphosate and neonicotinoid chemicals in crop fields hurt butterflies, along with other pesticides and herbicides. The use of chemicals, however, can actually come back to hurt farmers, since butterflies are pollinators of many plants.

“Monarchs, in particular, are toxic to birds, which allows other, non-toxic butterflies to survive because they look like monarchs and therefore don’t get eaten,” Crone explained.

She added that artists and engineers have observed monarchs for inspiration. Navigation systems, for example, have even been modeled upon butterfly flight.

The insect’s beauty, however, is what tends to captivate us the most.

“So many people spent their childhoods watching monarch caterpillars transform into a chrysalis, then emerge as butterflies,” Jepsen said. “The story of their migration is amazing.”

A monarch butterfly on a milkweed plant

Given the new data, all of the researchers now believe that western monarch butterflies should be listed as a threatened species under the Endangered Species Act. Crone explained that the listing would help to motivate agencies and landowners to participate in conservation practices.

“Listing would also substantially raise awareness of the plight of monarchs and similar species,” she continued. “For example, many other butterfly species also seem to be less abundant now than 30 years ago.”

The researchers said homeowners can take part in the butterfly conservation effort too. They are encouraged to plant native, locally sourced milkweed plants. Xerces has a milkweed seed finder to help locate vendors. Homeowners should also include other native plants and monarch-attracting wildflowers in their gardens.

“Some common garden flowers, like petunias and geraniums, don’t produce nectar,” Crone explained. “Others, like pansies, provide nectar and are used by native insects.”

The scientists also urge homeowners to minimize “homogenous” land surfaces, like pavement and grass-only lawns, and to support organic and other wildlife-friendly gardening and farming practices.

At present, Schultz and her team are monitoring where and when monarchs breed across the West. They are working across five states: California, Nevada, Idaho, Oregon, and Washington. They are also involved in a joint five-year project evaluating the importance of species interactions for population viability of rare butterflies, and how these interactions might be impacted by climate change.

The scientists are in talks with scientists in Mexico about collaborating on the larger eastern monarch population that overwinters in Mexico.

The researchers encourage the public to participate in projects in North America, in addition to the Western Monarch Thanksgiving Count, aimed at collecting data about butterfly populations. These projects include the Western Monarch Milkweed Mapper, Project Monarch Health, Journey North, and the Monarch Larva Monitoring Project.

Read more at Seeker

Saturn’s Icy Moons Are a Little Less Mysterious Thanks to Cassini’s Long Mission

An artist rendering of the Cassini spacecraft entering orbit around Saturn.

The Cassini spacecraft will take a death plunge into Saturn next on September 15 after more than a decade observing the planet and its moons. Perhaps its greatest contribution to science is helping us learn about the many icy moons circling Saturn and its elegant rings. Scientists are interested in finding life outside of Earth, to see if it's similar to what we have on our own planet.

Icy moons are likely our best shot at finding microbes. That's because they have a ready source of heat — in this case, tidal interactions with Saturn — as well as abundant water in the form of oceans and lakes. Cassini's observations from orbit showed us geysers, oceans, and other signs of liquid. Future missions on the drawing board might use submarines or little rovers to take a close-up look at the moons.

Here are some of Cassini's key discoveries.

Enceladus

Enceladus is perhaps the most famous icy moon of Saturn, as Cassini has tracked at least 101 geysers spouting water into space from "tiger stripes" or cracks in the ice. Late in Cassini's mission, in April 2017, researchers announced that Cassini detected hydrogen in Enceladus’s plumes, which suggests that there are hydrothermal vents in the ocean below. These vents are warm spots that, on Earth, are places where creatures tend to congregate as it is a ready-made source of energy and food.

Photograph of Enceladus, the sixth-largest moon of Saturn

Perhaps the most notable discovery was in September 2015, when researchers found evidence of a global ocean, based on how the moon wobbles as it orbits Saturn. Other key discoveries included evidence that Enceladus’s spouting water lands in Saturn's atmosphere and that the south polar area changes over time, hinting at evidence of Earth-like plate tectonics. It also recorded multiple observations of the geysers’ composition, structure, and eruption frequency.

This view of Titan, the largest of Saturn's 56 known moons, was taken on 26 December 2005 and reveals structure in the moon's complex atmosphere.

Titan

Scientists knew very little about the surface of Titan because observations showed only an orange blob. Cassini changed that forever, using radar to reveal a world of hydrocarbon-filled lakes that shift with the changing seasons.

Its mission began with the deployment of the European Space Agency’s Huygens lander, which flew to the surface in January 2005. Huygens made the first measurements from the lower atmosphere, finding — to the surprise of investigators — methane, even though the gas is typically broken down by the sun. This means that there is likely a renewable source of methane somewhere on Titan.

Cassini also made several science discoveries of its own, such as finding a disappearing and reappearing island on Titan's surface, watching the evolution of Titan's seasons, and finding evidence of an underground ocean.

Rhea, moon of the planet Saturn, assembled from a composition of multiple photos taken by the Voyager 1 spacecraft, 1980

Rhea

While Rhea is not reported on as much as Titan and Enceladus, it is notable because of its size — it's the second-largest of Saturn’s moon, although at 475 miles (764 kilometers) it is only a third of the radius of Titan. Its surface is likely made of water ice because it is so reflective of light. High reflectivity is also apparent on the small moons Dione and Tethys.

Cassini showed that Rhea likely has a mixture of ice and rock underneath its surface. Cassini also revealed canyons on Rhea — showing that the moon must have had tectonic movement long ago — as well as a wispy atmosphere of oxygen and carbon dioxide. Rings were also found in 2008.

This NASA Cassini Spacecraft image obtained 24 November, 2004 shows Saturn's icy moon Tethys

Tethys

Tethys, a small icy moon of Saturn, has mysterious red arcs on its surface that Cassini first detected in 2004. The scientists are not sure about the source of the arcs, but speculation includes chemical impurities in the ice, or perhaps fractures that are just a little bit smaller than what Cassini's cameras were able to resolve.

Cassini also found a heat signature on Titan that resembles the shape of the 1980s video game character Pac-Man. The approximately V-shaped structure likely happens when electrons, traveling at high speed around Saturn, crash onto the moon. The electron collision turns the soft surface into hard ice, which would not heat up as fast during the day, or cool down as quickly during the night, compared to the surrounding surface. A similar heat signature is present on Mimas.

Read more at Seeker

Pluto features given first official names

Pluto's first official surface-feature names are marked on this map, compiled from images and data gathered by NASA's New Horizons spacecraft during its flight through the Pluto system in 2015.

The IAU has assigned names to fourteen geological features on the surface of Pluto. The names pay homage to the underworld mythology, pioneering space missions, historic pioneers who crossed new horizons in exploration, and scientists and engineers associated with Pluto and the Kuiper Belt. This is the first set of official names of surface features on Pluto to be approved by the IAU, the internationally recognised authority for naming celestial bodies and their surface features.

NASA's New Horizons team proposed the names to the IAU following the first reconnaissance of Pluto and its moons by the New Horizons spacecraft. Some of the names were suggested by members of the public during the Our Pluto campaign, which was launched as a partnership between the IAU, the New Horizons project and the SETI Institute. Other names had been used informally by the New Horizons science team to describe the many regions, mountain ranges, plains, valleys and craters discovered during the first close-up look at the surfaces of Pluto and its largest moon, Charon.

"We're very excited to approve names recognising people of significance to Pluto and the pursuit of exploration as well as the mythology of the underworld. These names highlight the importance of pushing to the frontiers of discovery," said Rita Schulz, chair of the IAU Working Group for Planetary System Nomenclature. "We appreciate the contribution of the general public in the form of their their naming suggestions and the New Horizons team for proposing these names to us."

More names are expected to be proposed to the IAU, both for Pluto and for its moons. "The approved designations honour many people and space missions who paved the way for the historic exploration of Pluto and the Kuiper Belt, the most distant worlds ever explored," said Alan Stern, New Horizons Principal Investigator from the Southwest Research Institute (SwRI) in Boulder, Colorado.

The approved Pluto surface feature names are listed below.

Tombaugh Regio honours Clyde Tombaugh (1906-1997), the U.S. astronomer who discovered Pluto in 1930 from Lowell Observatory in Arizona.

Burney crater honors Venetia Burney (1918-2009), who as an 11-year-old schoolgirl suggested the name "Pluto" for Clyde Tombaugh's newly discovered planet. Later in life she taught mathematics and economics.

Sputnik Planitia is a large plain named after Sputnik 1, the first space satellite, launched by the Soviet Union in 1957.

Tenzing Montes and Hillary Montes are mountain ranges honouring Tenzing Norgay (1914-1986) and Sir Edmund Hillary (1919-2008), the Indian/Nepali Sherpa and New Zealand mountaineer who were the first to reach the summit of Mount Everest and return safely.

Al-Idrisi Montes honours Ash-Sharif al-Idrisi (1100-1165/66), a noted Arab mapmaker and geographer whose landmark work of medieval geography is sometimes translated as "The Pleasure of Him Who Longs to Cross the Horizons."

Djanggawul Fossae defines a network of long, narrow depressions named for the Djanggawuls, three ancestral beings in indigenous Australian mythology who travelled between the island of the dead and Australia, creating the landscape and filling it with vegetation.

Sleipnir Fossa is named for the powerful, eight-legged horse of Norse mythology that carried the god Odin into the underworld.

Virgil Fossae honors Virgil, one of the greatest Roman poets and Dante's fictional guide through hell and purgatory in the Divine Comedy.

Adlivun Cavus is a deep depression named for Adlivun, the underworld in Inuit mythology.

Hayabusa Terra is a large land mass saluting the Japanese spacecraft and mission (2003-2010) that returned the first asteroid sample.

Voyager Terra honours the pair of NASA spacecraft, launched in 1977, that performed the first "grand tour" of all four giant planets. The Voyager spacecraft are now probing the boundary between the Sun and interstellar space.

Tartarus Dorsa is a ridge named for Tartarus, the deepest, darkest pit of the underworld in Greek mythology.

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