Heavens

How complete is our census of the Sun’s closest neighbors? Astronomers using NSF’s NOIRLab facilities and a team of data-sleuthing volunteers participating in Backyard Worlds: Planet 9, a citizen science project, have discovered roughly 100 cool worlds near the Sun — objects more massive than planets but lighter than stars, known as brown dwarfs. Several of these newly discovered worlds are among the very coolest known, with a few approaching the temperature of Earth — cool enough to harbor water clouds.

Discovering and characterizing astronomical objects near the Sun is fundamental to our understanding of our place in, and the history of, the Universe. Yet astronomers are still unearthing new residents of the Solar neighborhood. A remarkable breakthrough was announced today, with the discovery of roughly 100 cool brown dwarfs near the Sun [1]. The new Backyard Worlds discoveries bridge a previously empty gap in the range of low-temperature brown dwarfs, identifying a long-sought missing link within the brown dwarf population.

“These cool worlds offer the opportunity for new insights into the formation and atmospheres of planets beyond the Solar System,” said Aaron Meisner from the National Science Foundation’s NOIRLab and the lead author of the research paper. “This collection of cool brown dwarfs also allows us to accurately estimate the number of free-floating worlds roaming interstellar space near the Sun.”

This major advancement was made possible with archival data from the Nicholas U. Mayall 4-meter Telescope at Kitt Peak National Observatory (KPNO) and the Víctor M. Blanco 4-meter Telescope at Cerro Tololo Inter-American Observatory (CTIO), which were made available through the Community Science and Data Center (CSDC), all programs of NSF’s NOIRLab. Large survey data sets were then made available to the Backyard Worlds volunteers using NOIRLab’s Astro Data Lab science platform. The results, to be published in TheAstrophysical Journal, demonstrate the rapidly growing role of survey and archival data research in astronomy today.

Brown dwarfs lie somewhere between the most massive planets and the smallest stars. Lacking the mass needed to sustain nuclear reactions in their core, brown dwarfs resemble cooling embers. Their low mass, low temperature and lack of internal nuclear reactions make them extremely faint — and therefore extremely difficult to detect. Because of this, when searching for the very coolest brown dwarfs, astronomers can only hope to detect such objects relatively close to the Sun.

To help find our Sun’s coldest and nearest neighbors, the astronomers of the Backyard Worlds project turned to a worldwide network of more than 100,000 citizen scientists [2]. These volunteers diligently inspect trillions of pixels of telescope images to identify the subtle movements of brown dwarfs and planets. Despite the abilities of machine learning and supercomputers, there’s no substitute for the human eye when it comes to scouring telescope images for moving objects.

The keen eyes of the Backyard Worlds volunteers have already discovered more than 1,500 cold worlds near to the Sun, and today’s paper presents roughly 100 of the coldest in that sample. According to Meisner, this is a record for any citizen science program by a factor of about 20, and 20 citizen scientists are listed as co-authors of the study. A handful of these cool worlds — which are among the very coldest brown dwarfs known — approach the temperature of Earth. NASA’s Spitzer Space Telescope provided the brown dwarf temperature estimates [3].

Brown dwarfs are expected to cool as they age, passing from near-stellar temperatures down to planetary temperatures and below, fading all the while and eventually winking out. The new discoveries attest to this picture by uncovering elusive examples of brown dwarfs approaching Earth-temperature.

“This paper is evidence that the solar neighborhood is still uncharted territory and citizen scientists are excellent astronomical cartographers,” said co-author Jackie Faherty of the American Museum of Natural History. “Mapping the coldest brown dwarfs down to the lowest masses gives us key insights into the low-mass star formation process while providing a target list for detailed studies of the atmospheres of Jupiter analogs.” 

Citizen scientist, Astro Data Lab user, and paper co-author Jim Walla added, “It’s awesome to know that our discoveries are now counted among the Sun’s neighbors and will be targets of further research.”

Alongside the dedicated efforts of the Backyard Worlds volunteers, NOIRLab’s Astro Data Lab was instrumental in this research. The technical burden of downloading billion-object astronomical catalogs is typically insurmountable for individual investigators — including most professional astronomers. “AstroData Lab’s open and accessible web portal allowed Backyard Worlds citizen scientists to easily query massive catalogs for brown dwarf candidates,” explained NOIRLab astronomer Stephanie Juneau, who helped introduce the citizen scientists to Astro Data Lab. Astro Data Lab also enables convenient matching between data sets from NOIRLab telescopes and external facilities, such as NASA’s WISE satellite, that jointly contributed to these brown dwarf discoveries.

In addition to Astro Data Lab’s making data accessible to the Backyard Worlds collaboration, archival observations by telescopes at two other NOIRLab Programs — CTIO and KPNO — were also key to this discovery. “Wide-area imaging from NOIRLab’s Mayall and Blanco telescopes was also critical,” explained Aaron Meisner. “To select only the very coldest brown dwarfs, we inspected deep images from a variety of sensitive astronomical surveys.”

“It’s great to see such thrilling results from NOIRLab’s efforts to broaden participation in astronomy research,” said Chris Davis of the National Science Foundation, the US agency that supports operations at the Kitt Peak and Cerro Tololo observatories and at CSDC. “By making archival data from NSF’s Mayall and Blanco telescopes publicly available and easily accessible through CSDC, folks with a fascination for astronomy can make a real contribution to science and to our understanding of the Universe.”

The approach of the Backyard Worlds project — searching for rare objects in large data sets — is also one of the goals for the upcoming Vera C. Rubin Observatory [4]. Currently under construction on Cerro Pachón in the Chilean Andes, Rubin Observatory will image the visible sky from the southern hemisphere every three nights over ten years, providing a vast amount of data that will enable new ways of doing astrophysical research.

“Vast modern data sets can unlock landmark discoveries, and it’s exciting that these could be spotted first by a citizen scientist,” concludes Aaron Meisner. “These Backyard Worlds discoveries show that members of the public can play an important role in reshaping our scientific understanding of our solar neighborhood.”

Scientists at Skolkovo Institute of Science and Technology (Skoltech), together with colleagues from the Karl-Franzens University of Graz & the Kanzelhöhe Observatory (Austria), Jet Propulsion Laboratory of California Institute of Technology (USA), Helioresearch (USA) and Space Research Institute of the Russian Academy of Sciences (Russia) developed a method to study fast Coronal Mass Ejections, powerful ejections of magnetized matter from the outer atmosphere of the Sun. The results can help to better understand and predict the most extreme space weather events and their potential to cause strong geomagnetic storms that directly affect the operation of engineering systems in space and on Earth. The results of the study are published in the Astrophysical Journal.

Coronal Mass Ejections are among the most energetic eruptive phenomena in our solar system and the main source of major space weather events. Huge clouds of plasma and magnetic flux are ejected from the atmosphere of the Sun into the surrounding space with speeds ranging from 100 to 3500 km/s. These gigantic solar plasma clouds and the accompanying powerful shock waves can reach our planet in less than a day, causing severe geomagnetic storms posing hazards to astronauts and technology in space and on Earth. One of the strongest Space Weather events occurred in 1859 when the induced geomagnetic storm collapsed the whole telegraph system in North America and Europe, the main means of communication for business and personal contacts in those days. If such an event occurs today, then modern devices are in no way protected. We may find ourselves without electricity, television, the Internet, radio communications which would lead to significant and cascading effects in many areas of our life. Only a few years ago, in July 2012, an outburst of energy comparable to the event in the 19th century occurred on the Sun, but we were lucky because these outbursts did not touch the Earth. According to some experts, the damage from such an extreme event could cost up to several trillion dollars and the restoration of infrastructure and the economy could take up to 10 years. Thus, understanding and forecasting of the most hazardous extreme events is of prime importance for the protection of the society and technology against the global hazards of Space Weather.

The current research resulted from an earlier work of Dr. Alexander Ruzmaikin, a former Ph.D. student of Academician Yakov Zeldovich and Dr. Joan Feynman, who has made important contributions to the study of Sun-Earth relations, the solar wind and its impact on the Earth magnetosphere, and who is the younger sister of Nobel Prize laureate Richard Feynman. In the current study, it was shown that the strongest and most intense geomagnetic storms are driven by fast Coronal Mass Ejections interacting in the interplanetary space with another Coronal Mass Ejection. Such interplanetary interactions among Coronal Mass Ejections occur in particular when they are launched in sequence one after another from the same active region. This type of ejection can be characterized using the concept of clusters that also generates an enhanced particle acceleration compared to the isolated plasma cloud. In general, the detection of clusters has important applications in many other extreme geophysical events such as floods and major earthquakes, as well as in interdisciplinary areas (hydrology, telecommunications, finance, and environmental studies).

"Understanding the characteristics of extreme solar eruptions and extreme space weather events can help us better understand the dynamics and variability of the Sun as well as the physical mechanisms behind these events," says a research scientist of the Skoltech Space Center and the first author of the study, Dr. Jenny Marcela Rodríguez Gómez.

Now we are at the beginning of a new 11-year cycle of solar activity, which, according to the predictions, will not be very strong. "However, this does not mean that no extreme events can happen", says professor Astrid Veronig, co-author of the study and director of Kanzelhöhe Observatory of the University of Graz. Historically, extreme space weather events occurred during not-so-strong cycles or during the descending phase of a cycle. At the peak of the solar cycle, vast amounts of energy are released in the form of numerous Solar Flares and Coronal Mass Ejections. whereas during the descending phase of a cycle the energy accumulates and may be released in single but very powerful events. "Therefore, our modern technological society needs to take this seriously, study extreme space weather events, and also understand all the subtleties of the interactions between the Sun and the Earth. And whatever storms may rage, we wish everyone good weather in space," says Tatiana Podladchikova, assistant professor at the Skoltech Space Center, research co-author.

According to a 2018 United Nations report, more than 25,000 individuals are officially reported to be victims of trafficking each year. The true number is likely much larger. While scientists have tried to help pinpoint outfits participating in sex trafficking, few scientific studies have looked of how the digital infrastructure behind the online sex market operates. A paper in Applied Network Science from Mayank Kejriwal, a research assistant professor at the USC Information Sciences Institute and Yao Gu (currently at Amazon) provides some insights on the specific digital practices of potential sex trafficking networks.

The researchers studied just under 40,000 accounts affiliated with the now defunct Backpage.com in the UK which was shut down for hosting online advertisements associated with sex trafficking, and discovered linked activities among these accounts in relation to advertisements placed. The common behaviors of these linked "activity networks" were visible in ads placed by the networks on Backpage.com and may, in fact, be clues to help identify illegal trafficking activity in the future.

The researchers believe that prior theories that aimed to identify sex trafficking organizations based on the sheer amount of online activity were insufficient but rather the connectivity of these accounts and joint activities pointed to the likely presence of a sex trafficking operation.

The researchers found that sex trafficking organizations often try to elude detection by:

Placing ads that move from city from city after a few days

Emphasizing foreign origins of female escorts

Changing names associated with the same ads

Emphasizing young age of companions -but also state as old as "99," which researchers believe may function as a code (for example, advertising certain kinds of 'services') to prospective customers

Mayank, the study's lead author who has previously worked to identify sex-trafficking sources on the dark web, said, "This is one of those studies that NGOs and other survivor-oriented organizations may find useful, since it could allow them to intervene more effectively, given limited resources. It could also serve as a model to study the structure of online sex markets in other countries."

Imagine if there were, say, 600 species of giraffes: some the size of a shrew, some three stories tall, some with purple spots. Of course, many giraffes could be found in Africa, but suppose there were reports of rare ones, wandering high in the mountains of the remote tropical island of New Guinea.

And also imagine that no one studied any of these species, that there were no giraffe experts anywhere. Now substitute "fern" for "giraffe" and you have some rough sense of the work of fern expert and University of Vermont research professor Michael Sundue--and why he's traveled to New Guinea on three expeditions to look for ferns.

In a study published August 5, in the journal Nature, Sundue, and three other UVM plant scientists, joined a global team of researchers from 56 institutions to present the first expert-verified checklist to the vascular plants of New Guinea and surrounding islands. So much uncertainty surrounded the number of New Guinea plants known to science that estimates ranged from 9,000 to 25,000. The researchers pored through digital records and plant collections scattered around the world, drawing on the expertise of 99 specialists--to tally 13,634 species in 264 families, with thousands yet to be discovered.

The team's work--supported by the US National Science Foundation and other funders--reveals that New Guinea is the world's richest island for plants.

BLACK HOLE

In his office, at The University of Vermont's renowned Pringle Herbarium, Sundue holds up a dried plant mounted on newsprint. "Oh that's sexy; that's a Selaginella," he says, pointing to a comely frond that looks a lot like a fern, but more technically is a lycophyte. "I'm not an expert on this. No one else studies this group of plants. There's no Selaginella expert on Earth--and there are 600 species worldwide."

Sundue is an expert on two other groups of ferns--which is why he was called in on the new Nature study. But his goal is not simply to count and identify plants. "The bigger question is where are biodiversity hotspots in the world--and why?" he says. "I've been trying to address that for ferns." New Guinea has been a "black hole," Sundue says, for many plants including ferns. "It's remote, dangerous, hard to get to with almost no roads. You can't just check an app or look at a museum collection--a lot of species have almost no records. So how are you supposed to interpret the evolution of plants on Earth--if you have missing pieces?" he says. "You have to go there and collect."

He holds up the dried plant from New Guinea in the bright Vermont sunshine. "That's a pretty handsome Selaginella," Sundue says. "It's one of the most ancient surviving lineages of plants on Earth."

MEGA-DIVERSITY

When the eighteenth-century Swedish botanist Carl Linnaeus set out to catalog all the world's plants and animals, he proposed their origin was a high mountain in Paradise: an island on the equator revealed when the primeval waters started to subside. "While his notion of one source area for all organisms was soon abandoned," says Rodrigo Camara-Leret--from the University of Zurich and the lead author on the new study--if he were alive today, Linneaus "would likely choose New Guinea as his symbol of a Paradise island teeming with life."

Except for the frozen rock of Greenland, New Guinea is the largest island in the world, just north of Australia and near the equator. Shaped like a crook-necked bird, it covers more than 300,000 square miles--nearly twice the size of California--with a huge spine of mountains that rise to over 16,000 feet. With very complex geology, New Guinea supports a dazzling array of ecosystems--some of the best-preserved on the planet--from mangrove jungles to alpine grasslands to ice-covered mountaintops. It's not surprising that its size and geographic diversity yields the world's richest island flora.

From his work in New Guinea and other places, "we can clearly see now that ferns are most diverse in tropical mountains," Sundue says--largely because "there are so many niches stacked on top of each other combined with the fact that there's low seasonality." This lets the ferns specialize on one habitat and climate type, genetically isolated from each other by rugged topography, leading to species formation.

Since the 17th century, botanists have described and named plants collected in New Guinea. Thousands of plants from the island are stored in herbaria there as well as the Netherlands, Great Britain and the US--including UVM. But despite advances in the past decades in clarifying the taxonomy of many New Guinea plants, publications about these plants have remained scattered, as botanists worked mostly independently from each other. "Great uncertainty remained as to how many plant species grew in New Guinea," says Camara-Leret. "Effectively, compared to other areas, like Amazonia which had plant checklists recently published, New Guinea remained the 'Last Unknown'"-- until the publication of this new study in Nature.

MORE TO DISCOVER

The results show that New Guinea has 19% more species than Madagascar and 22% more species than Borneo--making it the richest island in the world for plants. Also the new research shows that 68% of New Guinea's plants are only found on that island; this high level of endemism is unmatched in tropical Asia. "And it reveals the value of experts," says Sundue, including fellow fern experts--David Barrington, chair of UVM's Department of Plant Biology; recent UVM doctoral student Weston Testo; and Pedro Schwartsburd, a long-term visitor to Sundue's lab from Brazil--and co-authors on the new Nature study. Using online taxonomic platforms alone, the scientists estimate, would have inflated the species count in New Guinea by 22%--many thousands of false data points or confused names.

"The study also shows that we need to invest in training a large group of young and resident taxonomists in New Guinea," says Sundue. New Guinea plants have been mainly studied by non-resident experts, of whom 40% are retired or within ten years of turning 65 years old. But the team estimates that 3-4,000 new plants could be added to their checklist in the next few decades if there is long-term support for developing a new generation of local experts. "Land-use change is an increasing threat so more botanical exploration is therefore urgently needed if unknown species are to be collected before they disappear," the team writes in the new study.

"A checklist may not seem that interesting," Sundue says, "but it's foundational"--giving future studies greater accuracy and clearer targets, like focusing DNA work on species in particularly rich groups and "identifying blank spots on the map to go explore," Sundue says. "Biologists are trying to put together the history of life on Earth and that is done by examining all of the constituent organisms that live here," he says, "not just the ones that are easy to find."

Researchers from Kobe University and the National Institute of Technology, Oshima College have conducted a detailed reanalysis of image data from Voyager 1, 2 and Galileo spacecraft in order to investigate the orientation and distribution of the ancient tectonic troughs found on Jupiter's moon Ganymede. They discovered that these troughs are concentrically distributed across almost the entire surface of the satellite. This global distribution indicates that these troughs may be actually part of one giant crater covering Ganymede.

Based on the results of a computer simulation conducted using the "PC Cluster" at the National Astronomical Observatory of Japan (NAOJ), it is speculated that this giant crater could have resulted from the impact of an asteroid with a radius of 150km. If so, the structure is the largest impact structure identified in the solar system so far.

The European Space Agency's JUICE (Jupiter Icy Moon Explorer) mission, which will be launched in 2022 and arrive in Jupiter's system in 2029, aims to increase our knowledge regarding Jupiter's satellites, including Ganymede. It is hoped that this exploration will confirm the results of this study and further advance our understanding of the formation and evolution of Jupiter's satellites.

The research team consisted of Kobe University Graduate School of Science's Assistant Professor HIRATA Naoyuki and Professor OHTSUKI Keiji (both of the Department of Planetology), and Associate Professor SUETSUGU Ryo of National Institute of Technology, Oshima College. The paper for this study was published online in Icarus on July 15.

Main Points

Many furrows, or trough formations, have been previously observed on the surface of Ganymede, one of Jupiter's moons.

The research group comprehensively reanalyzed image data of Ganymede's surface obtained by NASA's Voyager 1, Voyager 2 and Galileo spacecraft.

The results revealed that almost all of these furrows on the surface of Ganymede appear to be in concentric rings centered at a single point, indicating that this global multiring structure may be the remains of a giant crater.

The radial extent of the multiring measured along the satellite's surface is 7800km. Therefore, if it is actually formed by an impact, it is the largest vestigial impact crater discovered in the solar system so far.

The results of the numerical impact simulation indicated that an asteroid with a radius of 150km impacting Ganymede at a speed of 20km/s would explain the observed structures on the satellite's surface.

Research Background

Both Voyager 1 and Voyager 2 have closely approached Ganymede in 1979 and 1980 respectively, taking detailed images of the surface. In addition, the Galileo spacecraft orbited Jupiter from 1995 to 2003, obtaining a large amount of Ganymede image data. Ganymede is the largest satellite in the solar system and is bigger than both Pluto and Mercury. The formation and evolution of Jupiter's moons including Ganymede is strongly connected to the formation and evolution of the Jupiter system, and by extension, of the solar system. Consequently, there are various ongoing and planned spacecraft missions to explore the satellite system, including NASA's JUNO mission that is ongoing, the Europa Clipper scheduled to perform a detailed investigation of Jupiter's moon Europa in around 2030, and the aforementioned JUICE mission.

The study was conducted with the aims of clarifying one aspect of the formation and evolution of Jupiter's satellites and of contributing towards these spacecraft missions. The group reanalyzed image data of Ganymede. In particular, the researchers focused on furrows (Figure 1), tectonic troughs that are believed to be the oldest surface features on the satellite. Therefore, the research group hypothesized that they could reconstruct the early history of Ganymede by analyzing these geological formations.

Research Findings

Ganymede's surface is categorized into areas of Dark Terrain and Bright Terrain. Dark Terrain is extremely old and has many remaining craters, as well as trough formations (Figure 1). Bright Terrain is comparatively recent, with hardly any craters. These two types of terrain are not coherently arranged and are randomly distributed over Ganymede's entirety. Furrows are believed to be Ganymede's oldest geological features because they are only found on Dark Terrain and many impact craters (*1) have been formed on top of them later on.

This study reanalyzed the distribution of these trough formations over Ganymede's entire surface, revealing for the first time that almost all of these furrows are concentrically aligned around a single point (Figure 2). The study showed that these furrows form giant, concentric rings over the entire satellite. From this, it can be assumed that there was a giant multiring impact crater which covered the entire surface of Ganymede before the formation of the Bright Terrain areas. A similar ring structure known as the Valhalla Crater remains on the surface of Callisto, another satellite of Jupiter. Until now, the Valhalla Crater has been the largest identified multiring crater in the solar system, with a radius of approximately 1900km. However, the multiring crater on Ganymede has a radial extent of 7800km measured along the satellite's surface.

The research team conducted a simulation to estimate the scale of the impact that formed this giant crater. This was carried out using the "PC Cluster" at the National Astronomical Observatory of Japan (NAOJ). The results indicated that an asteroid with a radius of 150km impacting Ganymede at a speed of 20km/s would be sufficient to form the observed structures on the satellite's surface (Figure 3). It is believed that such an impact occurred around 4 billion years ago.

Further Developments

The discovery that the aftermath of a large-scale impact remains on Ganymede's surface is greatly significant in terms of the satellite's formation process and evolution. For example, Jupiter's satellite Callisto is around the same size as Ganymede, however it is believed that it doesn't have an internal structure composed of differentiated layers. On the other hand, Ganymede is thought to be composed of a differentiated layer structure consisting of rock, iron and ice. An enormous amount of heat is necessary to form these differentiated layers. It is possible that the aforementioned large-scale impact could have been the source of this heat.

This study's discovery will also have substantial significance for the Ganymede exploration programs scheduled in the coming decades. The image data from both Voyager and Galileo missions only provide partial views of the satellite's surface. It is hoped that future explorations will be able to confirm or test this study's results by conducting detailed investigations into the multiring formations and whether or not there are any other remains of large-scale impacts. Hopefully, this will result in a deeper understanding of the origins and evolution of Ganymede as well as Jupiter's other moons.

It is not yet possible to predict earthquakes, but the analysis of different types of seismic data allows scientists to pinpoint where and when each type of earthquake originated, and hence better understand when and where tectonic slip might occur via damaging earthquakes. Tens of thousands of seismic stations around the world continuously record local seismic activity, with an output that is far beyond what scientists can process. Here, researchers from Northwestern University have called over 2,000 citizen scientists to the rescue for the crowd-based analysis of seismic recordings, rendered into audiovisual format, through the program Earthquake Detective on the Open-Science platform Zooniverse. They show that citizens are at least as accurate as machine learning, and can even identify tectonic tremors, which previously was only possible for trained professionals. The results are published today in Frontiers in Earth Science.

"My aim was to receive help with detections of these special seismic events because I felt overwhelmed by the rapidly growing mountain of data I was investigating for my PhD research," says lead author Vivian Tang, a graduate student at the Department of Earth and Planetary Sciences of Northwestern University, Illlinois. "With Zooniverse and the Earthquake Detective team, we provide people everywhere with a simple and engaging way to help further scientific research."

After completing a tutorial and practice session, each citizen scientist was asked to listen to a random selection from among 2,467 recordings captured by seismic stations across Alaska, part of the USArray of stations across North America. Visual traces were shown alongside the audio data. Each recording corresponded to the first 2,000 seconds (but sped up 800 times to audible frequencies) after the estimated arrival at each station of the surface waves from one of 30 known major earthquakes that occurred somewhere in the world between between 2013 and 2018. When the wave from a faraway earthquake reaches a seismically active location such as Alaska, where the Pacific tectonic plate slides under the North American, it may trigger local seismic events, such as smaller earthquakes or tectonic tremors, which are series of thousands of slow, tiny vibrations deep inside the Earth's crust that may last for days or weeks. Tremors were first discovered in 2001 and have since become an important focus of study, because they show us where tectonic slip occurs without earthquakes, yet are thought to play a role in the origin of earthquakes.

Each recording was presented to ten different citizens, who had to classify it as an earthquake, tremor, background noise, or none of the above. Sped up, the seismic recordings of earthquakes typically sound like a slamming door, while tremor sounds like a train going over railway tracks, and background noise can sound like whistling wind, crinkling tin foil, or radio static. The researchers used the number of citizens agreeing on each classification as a measure of the degree of consensus. A selection of the dataset was also classified by trained seismologists among the authors, while output from a machine learning algorithm developed specifically by them to identify earthquakes were used as a benchmark for the citizens' performance. Artificial intelligence has not yet been able to identify tectonic tremor, which until the present study where citizens successfully mastered this task, could only be recognized within seismic data by seismologists.

The citizens reached a collective decision for 91% of the tested recordings. There was more consensus when classifying earthquakes (74% of recordings with this collective decision reached the preset threshold of 40% votes for the majority classification) than for tremor (51%) and background noise (66%). When their collective decision was compared to the correct classification, as determined by the professional scientists, the citizens were collectively 85% accurate in identifying earthquakes, higher than the 76% accuracy of the machine learning algorithm.

The authors conclude that citizen scientists can make a major contribution to seismology, allowing scientists to process much more data than they ever could on their own, thus helping them to better understand processes deep inside the Earth's crust and forecast earthquakes with greater precision. The citizens' ability to collectively identify tremors, which artificial intelligence can't yet do, will be especially valuable for the field.

"Earthquake Detective can be a resource for other researchers in this field who are interested in receiving input from an impressive group of volunteer scientists. We strongly encourage these researchers to point us to seismograms they would like to see classified, so that we can include them in Earthquake Detective, and return the volunteer classifications to the researchers," says Tang.

Every night on Mars, when the sun sets and temperatures fall to minus 80 degrees Fahrenheit and below, an eerie phenomenon spreads across much of the planet's sky: a soft glow created by chemical reactions occurring tens of miles above the surface.

An astronaut standing on Mars couldn't see this "nightglow"--it shows up only as ultraviolet light. But it may one day help scientists to better predict the churn of Mars' surprisingly complex atmosphere.

"If we're going to send people to Mars, we better understand what's going on in the atmosphere," said Zachariah Milby, a professional research assistant at the Laboratory for Atmospheric and Space Physics (LASP) at CU Boulder.

In a study published today in the Journal of Geophysical Research: Space Physics, Milby and his colleagues set their sights on understanding the phenomenon. They drew on data from NASA's Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft to map the planet's nightglow in greater detail than ever before.

The team's findings show how this light display ebbs and flows over Mars' seasons. The group also discovered something unusual: an unexpectedly bright spot that appears in the planet's atmosphere just above its equator.

Mars, in other words, still has a few surprises in store for scientists, said LASP's Nick Schneider, lead author of the new study.

"The behavior of the Martian atmosphere is every bit as complicated and insightful as that of Earth's atmosphere," said Schneider, also a professor in the Department of Astrophysical and Planetary Sciences.

Full picture

MAVEN wasn't the first spacecraft to spot the nightglow on Mars, a phenomenon that resembles similar glows seen on Earth and Venus. That honor belongs to the European Space Agency's Mars Express Mission, which entered orbit around Mars in 2003.

But the mission was the first to capture the nightglow for what it is--a dynamic and constantly evolving phenomenon.

"It wasn't until MAVEN came along in 2014 that we could actually snap this full picture five times a day as the planet rotates," Schneider said.

In the new study, researchers used MAVEN's Imaging Ultraviolet Spectrograph (IUVS)--an instrument designed and built at LASP--to snap images of Mars from a distance of 3,700 miles. Those far-flung recordings allowed the team to trace the path of nightglow as it moved across the entire planet.

Milby led the data analysis for the research while he was still an undergraduate student at CU Boulder.

He explained that the eerie aura appears when air currents high in Mars' atmosphere plunge to about 40 miles above the planet's surface. When that happens, lone nitrogen and oxygen atoms in the atmosphere combine to form molecules of nitric oxide, giving off small bursts of ultraviolet light in the process.

Put differently, when its atmosphere drops, Mars shines.

"It's a great tracer for dynamics between the layers of the atmosphere," Milby said.

Bright spots

Milby added that, like on Earth, those dynamics can shift with the seasons. The MAVEN team found, for example, that Mars' nightglow seems to be brightest at the height of the planet's northern and southern winters when hotter currents rush away from the equator and toward Mars' poles.

Milby also found something he wasn't expecting in the data: an extra-bright blob of nightglow that appeared and disappeared from almost exactly above 0 degrees longitude and 0 degrees latitude on Mars.

"We spent weeks thinking there was a bug in our code somewhere," Milby said.

There wasn't a bug. The researchers still aren't sure why Mars is glowing so much at that unusual spot--it may have something to do with the shape of the terrain underneath. But Schneider said that observations like this can help scientists improve their computer models of how the planet's atmosphere works.

And that could lead to something that every astronaut might use: more accurate weather reports on Mars.

"We use supercomputers to predict weather on Earth so that you can plan for your vacation or growing crops," Schneider said. "The same computer models can be spun up for Mars and all the other planets."

ITHACA, N.Y. - NASA's Juno spacecraft - orbiting and closely observing the planet Jupiter - has unexpectedly discovered lightning in the planet's upper atmosphere, according to a multi-institutional study led by the NASA/Jet Propulsion Laboratory (JPL), which includes two Cornell University researchers.

The work was published Aug. 5 in the journal Nature.

Jupiter's gaseous atmosphere seems placid from a distance, but up close the clouds roil in a turbulent, chemically dynamic realm. As scientists have probed the opaque surface with Juno's sensitive instrumentation, they've learned that Jupiter's lightning occurs not only deep within the water clouds but also in shallow atmospheric regions (at high altitudes with lower pressure) that feature clouds of ammonia mixed with water.

"On the night side of Jupiter, you see fairly frequent flashes - as if you were above an active thunderstorm on Earth," said Jonathan I. Lunine, the David C. Duncan Professor in the Physical Sciences and chair of the Department of Astronomy in the College of Arts and Sciences at Cornell University. "You get these tall columns and anvils of clouds, and the lightning is going continuously. We can get some pretty substantial lightning here on Earth, and the same is true for Jupiter."

The research, "Small Lightning Flashes From Shallow Electrical Storms on Jupiter," was directed by Heidi N. Becker, the Radiation Monitoring Investigation lead of NASA's Juno mission. Lunine and doctoral candidate Youry Aglyamov were the two Cornell co-authors in the study.

Previous missions to Jupiter - such as Voyager 1, Galileo and New Horizons - had all observed lightning. But thanks to Juno's Stellar Reference Unit, a camera designed to detect dim sources of light, the spacecraft's close observational distance and instrument sensitivity enabled lightning detection at a higher resolution than previously possible.

Ammonia is the key. While there is water and other chemical elements such as molecular hydrogen and helium in Jupiter's clouds, ammonia is the "antifreeze" that keeps water in those upper atmospheric clouds from freezing entirely.

Lunine notes Aglyamov's ongoing dissertation work focuses on how lightning is generated under these conditions. The collision of the falling droplets of mixed ammonia and water with suspended water-ice particles constitutes a way to separate charge and produce cloud electrification - resulting in lightning storms in the upper atmosphere.

"The shallow lightning really points to the role of ammonia, and Youry's models are starting to confirm this," Lunine said. "This would be unlike any process that occurs on Earth."

Jupiter's wild gaseous world fascinates Aglyamov.

"Giant planets in general are a fundamentally different kind of world from Earth and other terrestrial planets," he said. "There are hydrogen seas transitioning gradually into skies stacked with cloud decks, weather systems the size of the Earth and who-knows-what in the interior."

The discovery of shallow lightning on Jupiter shifts our understanding of the planet, Aglyamov said.

"Shallow lightning hadn't really been expected and indicates that there's an unexpected process causing it," he said. "It's one more way in which Juno's observations show a much more complex atmosphere of Jupiter than had been predicted. We know enough now to ask the right questions about processes going on there, but as Juno shows, we're in a stage where every answer also tends to multiply the questions."

Thanks to researchers from The University of Queensland, we now know with much greater certainty the nuclear magnetic moments of francium atoms.

Dr Ben Roberts, a postdoctoral research fellow in UQ's School of Mathematics and Physics, said that the nuclear magnetic moment is a fundamental property of atoms, and knowing its value precisely is important when testing fundamental physics theories.

"But because francium is radioactive, the standard techniques for determining nuclear magnetic moments can't easily be applied," Dr Roberts said.

"Using new methods, we were able to calculate moments with uncertainties four times smaller than the previous best values.

"Take francium-211, for example: its nuclear magnetic moment was previously determined to be in the range 3.92 to 4.08 (in the natural unit for expressing these moments).

"Our calculations now show it's between 3.90 and 3.94."

This may not seem like a huge difference, but Dr Jacinda Ginges, an ARC Future Fellow at UQ and Associate Investigator at the ARC Centre of Excellence for Engineered Quantum Systems (EQUS), said that when you're talking about atomic physics, small differences can have a huge effect, so narrowing the range of possible values is a big deal.

"Our current understanding of the fundamental particles that make up the Universe and their interactions relies on the standard model of particle physics, but we also know this model is incomplete, there are some things it can't explain," Dr Ginges said.

"We need precise values for nuclear magnetic moments to be able to test the validity of our atomic models, which in turn are really important for testing the standard model of particle physics.

"By combining precision experiments in atoms with high-precision atomic theory, we get a powerful way to search for new physics."

The improvement in precision was the result of very precise calculations of the hyperfine structure of francium--the tiny differences in atomic energy levels caused by its nuclear magnetic moment--and more accurate models of nuclear effects.

"Previous determinations assumed that the nucleus of a francium atom was like a ball with uniform magnetisation, but in our calculation we assumed a more realistic model that allowed the magnetisation to vary within the nucleus," Dr Roberts said.

"The effect of non-uniform magnetisation (known as the Bohr-Weisskopf effect) is especially large in francium, so by accurately taking this into account we were able to determine its nuclear magnetic moments much more precisely."

"Our results can now be used to benchmark atomic theory, which will help interpret experiments currently underway at Canada's national nuclear and particle physics facility, TRIUMF," Dr Ginges said.

"They also show how important it is to accurately model nuclear effects, and will have implications for past and future precision experiments with heavy atoms."

Planet-forming environments can be much more complex and chaotic than previously expected. This is evidenced by a new image of the star RU Lup, made with the Atacama Large Millimeter/submillimeter Array (ALMA).

All planets, including the ones in our Solar System, are born in disks of gas and dust around stars, so-called protoplanetary disks. Thanks to ALMA we have stunning high-resolution images of many of these planet factories, showing dusty disks with multiple rings and gaps that hint at the presence of emerging planets. The most famous examples of these are HL Tau and TW Hydrae.

But disks are not necessarily as neatly arranged as these initial dust observations suggest. A new ALMA image of RU Lup, a young variable star in the Lupus constellation, revealed a giant set of spiral arms made of gas, extending far beyond its more well-known dust disk. This spiral structure - resembling a 'mini-galaxy' - extends to nearly 1000 astronomical units (au) from the star, much farther away than the compact dust disk that extends to about 60 au.

Previous observations of RU Lup with ALMA, which were part of the Disk Substructures at High Angular Resolution Project (DSHARP, https://public.nrao.edu/news/2018-alma-survey-disks/), already revealed signs of ongoing planet formation, hinted by the dust gaps in its protoplanetary disk. "But we also noticed some faint carbon monoxide (CO) gas structures that extended beyond the disk. That's why we decided to observe the disk around the star again, this time focusing on the gas instead of the dust," said Jane Huang of the Center for Astrophysics, Harvard & Smithsonian (CfA) and lead author on a paper published today in the Astrophysical Journal.

Protoplanetary disks contain much more gas than dust. While dust is needed to accumulate the cores of planets, gas creates their atmospheres.

In recent years, high resolution observations of dust structures have revolutionized our understanding of planet formation. However, this new image of the gas indicates that the current view of planet formation is still too simplistic and that it might be much more chaotic than previously inferred from the well-known images of neatly concentric ringed disks

"The fact that we observed this spiral structure in the gas after a longer observation suggests that we have likely not seen the full diversity and complexity of planet-forming environments. We may have missed much of the gas structures in other disks," added Huang.

Huang and her team suggest several scenarios that could possibly explain why the spiral arms appeared around RU Lup. Maybe the disk is collapsing under its own gravity, because it is so massive. Or maybe RU Lup is interacting with another star. Another possibility is that the disk is interacting with its environment, accreting interstellar material along the spiral arms.

"None of these scenarios completely explain what we have observed," said team-member Sean Andrews of CfA. "There might be unknown processes happening during planet formation that we have not yet accounted for in our models. We will only learn what they are if we find other disks out there that look like RU Lup."

Our solar system has one habitable planet -- Earth. A new study shows other stars could have as many as seven Earth-like planets in the absence of a gas giant like Jupiter.

This is the conclusion of a study led by UC Riverside astrobiologist Stephen Kane published this week in the Astronomical Journal.

The search for life in outer space is typically focused on what scientists call the "habitable zone," which is the area around a star in which an orbiting planet could have liquid water oceans -- a condition for life as we know it.

Kane had been studying a nearby solar system called Trappist-1, which has three Earth-like planets in its habitable zone.

"This made me wonder about the maximum number of habitable planets it's possible for a star to have, and why our star only has one," Kane said. "It didn't seem fair!"

His team created a model system in which they simulated planets of various sizes orbiting their stars. An algorithm accounted for gravitational forces and helped test how the planets interacted with each other over millions of years.

They found it is possible for some stars to support as many as seven, and that a star like our sun could potentially support six planets with liquid water.

"More than seven, and the planets become too close to each other and destabilize each other's orbits," Kane said.

Why then does our solar system only have one habitable planet if it is capable of supporting six? It helps if the planets' movement is circular rather than oval or irregular, minimizing any close contact and maintain stable orbits.

Kane also suspects Jupiter, which has a mass two-and-a-half times that of all the other planets in the solar system combined, limited our system's habitability.

"It has a big effect on the habitability of our solar system because it's massive and disturbs other orbits," Kane said.

Only a handful of stars are known to have multiple planets in their habitable zones. Moving forward, Kane plans to search for additional stars surrounded entirely by smaller planets. These stars will be prime targets for direct imaging with NASA telescopes like the one at Jet Propulsion Laboratory's Habitable Exoplanet Observatory.

Kane's study identified one such star, Beta CVn, which is relatively close by at 27 light years away. Because it doesn't have a Jupiter-like planet, it will be included as one of the stars checked for multiple habitable zone planets.

Future studies will also involve the creation of new models that examine the atmospheric chemistry of habitable zone planets in other star systems.

Projects like these offer more than new avenues in the search for life in outer space. They also offer scientists insight into forces that might change life on our own planet one day.

"Although we know Earth has been habitable for most of its history, many questions remain regarding how these favorable conditions evolved with time, and the specific drivers behind those changes," Kane said. "By measuring the properties of exoplanets whose evolutionary pathways may be similar to our own, we gain a preview into the past and future of this planet -- and what we must do to main its habitability."

What The Study Did: This population epidemiology study estimates associations of school closures in the U.S. and the timing of those closures in March with change in daily COVID-19 incidence and mortality through the first week of May, accounting for other existing public health interventions.

Authors: Katherine A. Auger, M.D., M.Sc., of the Cincinnati Children's Hospital Medical Center in Ohio, is the corresponding author.

To access the embargoed study: Visit our For The Media website at this link https://media.jamanetwork.com/

(doi:10.1001/jama.2020.14348)

Editor's Note: The article includes conflict of interest and funding/support disclosures. Please see the article for additional information, including other authors, author contributions and affiliations, financial disclosures, funding and support, etc.

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Using information from a national database, investigators took an evidence-based approach to defining the lower limit of pulmonary vascular resistance

This new lower parameter can capture more patients who have pulmonary hypertension and are at risk for death or hospitalization

When most people think of high blood pressure, they think of being tested with an arm cuff at a doctor's appointment. That type of blood pressure is separate from pulmonary hypertension (PH), which is high blood pressure in the lung arteries. In a study published today in The Lancet Respiratory Medicine, investigators from Brigham and Women's Hospital took an evidence-based approach to determine the lower end of the risk spectrum for PH based on pulmonary vascular resistance (PVR), which is resistance against blood flow from the pulmonary artery to the lungs. The team presents evidence that by redefining the lower risk level for PVR, 60 percent more patients who are at risk for death due to PH can be diagnosed.

"The findings of this study cast the clinical profile of patients who have PH and are at risk for major clinical events into a new and wider light," said corresponding author Bradley Maron, MD, an associate physician in the Division of Cardiovascular Medicine at the Brigham. "We can use this information to raise awareness among clinicians on those patients that may need reconsideration for risk factor modification, conventional treatment, and potential clinical trial enrollment."

PH affects 70 million people worldwide across a broad age, geographic and socioeconomic spectrum. Left untreated, average survival is 2 to 3 years after diagnosis. PH can cause serious problems because changes in blood pressure in the lung arteries are not tolerated well by the heart and can lead to hospitalization, heart failure and death. Despite being a grave condition, the way PH was defined in clinical practice previously was not evidence-based and did not account for physiological changes in blood pressure, such as may occur due to circumstances that are immediately reversible. Although PVR was already considered important in the prognosis of PH, the actual range of PVR that is informative of PH was not known.

The researchers analyzed the association of PVR and mortality using the Veterans Association (VA) national database, which includes comprehensive information on patients' medical histories and clinical events. The researchers acknowledge the limitations to working with a national population relative to errors in measurements. Also, the VA population is almost entirely male, so the team validated the findings in a sex-balanced cohort at Vanderbilt University Medical Center to account for both men and women. The data analysis did account for comorbidities but was not positioned to distinguish between the different stages of diseases that could affect outcome, such as the degree of lung disease in individual patients.

The results indicated that starting at a PVR of around 2.2 Wood Units (a standard unit of measurement for PVR), there is an increase in association with mortality among patients with increased pulmonary artery pressure. This 2.2 level is well below what is currently associated with the disease in clinical practice. The new, lower threshold expands the range of patients who are considered to have PH and optimizes the specificity of PH criteria used clinically.

"Pulmonary hypertension is often overlooked in clinical practice, but this study provides a specific context for clinicians and health care workers to understand the range of risk for a large group of patients," said Maron. "We have established an evidence-based way to recognize patients with PH who would have otherwise been considered to be normal, but, in fact, have a concerning profile."

From here, the team is interested in looking at populations that were not included in this study, including patients with less common forms of PH or PH that exists in the absence of heart and lung disease.

Saturn is truly the lord of the rings in this latest snapshot from NASA's Hubble Space Telescope, taken on July 4, 2020, when the opulent giant world was 839 million miles from Earth. This new Saturn image was taken during summer in the planet's northern hemisphere.

Hubble found a number of small atmospheric storms. These are transient features that appear to come and go with each yearly Hubble observation. The banding in the northern hemisphere remains pronounced as seen in Hubble's 2019 observations, with several bands slightly changing color from year to year. The ringed planet's atmosphere is mostly hydrogen and helium with traces of ammonia, methane, water vapor, and hydrocarbons that give it a yellowish-brown color.

Hubble photographed a slight reddish haze over the northern hemisphere in this color composite. This may be due to heating from increased sunlight, which could either change the atmospheric circulation or perhaps remove ices from aerosols in the atmosphere. Another theory is that the increased sunlight in the summer months is changing the amounts of photochemical haze produced. "It's amazing that even over a few years, we're seeing seasonal changes on Saturn," said lead investigator Amy Simon of NASA's Goddard Space Flight Center in Greenbelt, Maryland. Conversely, the just-now-visible south pole has a blue hue, reflecting changes in Saturn's winter hemisphere.

Hubble's sharp view resolves the finely etched concentric ring structure. The rings are mostly made of pieces of ice, with sizes ranging from tiny grains to giant boulders. Just how and when the rings formed remains one of our solar system's biggest mysteries. Conventional wisdom is that they are as old as the planet, over 4 billion years. But because the rings are so bright - like freshly fallen snow - a competing theory is that they may have formed during the age of the dinosaurs. Many astronomers agree that there is no satisfactory theory that explains how rings could have formed within just the past few hundred million years. "However, NASA's Cassini spacecraft measurements of tiny grains raining into Saturn's atmosphere suggest the rings can only last for 300 million more years, which is one of the arguments for a young age of the ring system," said team member Michael Wong of the University of California, Berkeley.

Two of Saturn's icy moons are clearly visible in this exposure: Mimas at right, and Enceladus at bottom.

This image is taken as part of the Outer Planets Atmospheres Legacy (OPAL) project. OPAL is helping scientists understand the atmospheric dynamics and evolution of our solar system's gas giant planets. In Saturn's case, astronomers continue tracking shifting weather patterns and storms.

Some supposedly inert ingredients in common drugs -- such as dyes and preservatives -- may potentially be biologically active and could lead to unanticipated side effects, according to a preliminary new study by researchers from the UC San Francisco School of Pharmacy and the Novartis Institutes for BioMedical Research (NIBR).

Most medications include only a relatively small amount of their active pharmaceutical ingredient by mass (for instance, the acetaminophen in Tylenol and other medications). The rest of any given pill, liquid or injectable can be composed of ingredients including preservatives, dyes, antimicrobials and other compounds known as excipients. These ingredients play critical roles in making sure a drug's active ingredient is delivered safely and effectively, as well as conferring important qualities like shelf stability and the ability to quickly distinguish pills by color.

Excipients are generally accepted to be biologically inactive based on their long history of use, or because they don't produce any obvious toxicity in animal studies. But few studies have looked for more subtle effects of long-term exposure to these compounds or how they might interact in people who take multiple different medicines that include these ingredients.

Researchers Brian Shoichet, PhD, of the UCSF Department of Pharmaceutical Chemistry and Laszlo Urban, PhD, Global Head of Preclinical Safety Profiling at NIBR, had begun to wonder about whether all of these substances were really inert, and joined forces to investigate them. They began the work in 2017 with a database documenting most readily accessible pure excipients, which the UCSF group had compiled in an easy-to-use excipients browser, itself drawing on a more specialized FDA inactive ingredients database (IID), with support from the FDA-funded UCSF-Stanford Center of Excellence in Regulatory Science and Innovation (CERSI).

As reported in their new study, published July 23, 2020 online in Science, the researchers have now systematically screened 3296 excipients contained in the inactive ingredient database, and identified 38 excipient molecules that interact with 134 important human enzymes and receptors.

The research team emphasizes that their study, which did not look for actual effects on human patients, is only intended to flag molecules with the potential to pose negative health effects, and the examples they list will need to be further studied to understand how they might contribute to side effects of drugs in which they are found.

"These data illustrate that while many excipient molecules are in fact inert, a good number may have previously unappreciated effects on human proteins known to play an important role in health and disease," Shoichet said. "We demonstrate an approach by which drug makers could in the future evaluate the excipients used in their formulations, and replace biologically active compounds with equivalent molecules that are truly inactive."

The team used a couple of different approaches. At UCSF, Shoichet's team computationally examined excipient molecules that physically resemble the known biological binding partners of 3117 different human proteins in the public ChEMBL database. The team then computationally pared down 2 million possible interactions of these excipients and human target proteins to 20,000 chemically plausible interactions. Based on visual inspection, the researchers identified a subset of 69 excipients with highest likelihood of interacting with human target proteins, and tested these interactions experimentally in laboratory dishes, in collaboration with the groups of Bryan Roth, PhD, a professor of pharmacology at the University of North Carolina, Chapel Hill, and Kathy Giacomini, PhD, a professor of bioengineering at UCSF and co-director of the UCSF-Stanford CERSI center.

These experiments identified 25 different biological interactions involving 19 excipient molecules and 12 pharmacologically important human proteins.

In a complementary set of experiments at NIBR, the researchers screened 73 commonly used excipients against a panel of human protein targets involved in drug-induced toxicity and regularly used to test drug candidates for safety. They identified an additional 109 interactions between 32 excipients and these human safety targets.

"Our study was meant to expand on anecdotal evidence that excipients may be the culprits of unexpected physiological effects seen in certain drug formulations," said study lead author Joshua Pottel, PhD, a former postdoctoral researcher in the Shoichet lab who is now President and CEO of Montreal-based Molecular Forecaster Inc. "It was not so surprising to find new properties of understudied compounds that have been grandfathered in as 'inactive' for decades, but it was surprising to see how potent some of these molecules are, especially considering the fairly high quantities sometimes used in typical drug formulations."

The biologically active excipients the study identified in laboratory dishes merit further study in animal models to establish whether any of them may in fact produce unwanted side effects in human patients, the authors said. Many should be readily interchangeable with truly inert excipients of similar function, they said, but for others, new replacement compounds may need to be developed.

"After decades with little innovation in how drugs are formulated, we see this as an opportunity for a public-private partnership between academic, regulatory, and pharmaceutical communities to seek new and better excipients, and we demonstrate an approach to doing so," Shoichet said. "Given the challenge this work presents to the pharmaceutical status quo, we are grateful for the forward-thinking support the project has received primarily from the FDA and through our collaboration with Novartis, in addition to the National Institutes of Health."