пятница, 26 апреля 2019 г.

The day the asteroid might hit


Asteroid Watch logo.


26 April 2019


For the first time, ESA will cover a major international asteroid impact exercise live via social media, highlighting the the actions that might be taken by scientists, space agencies and civil protection organisations.



Visualisation of asteroid Itokawa

Every two years, asteroid experts from across the globe come together to simulate a fictional but plausible imminent asteroid impact on Earth. During the week-long scenario, participants – playing roles such as ‘national government’, ‘space agency’, ‘astronomer’ and ‘civil protection office’ – don’t know how the situation will evolve from one day to the next, and must make plans based on the daily updates they are given.


For the first time, ESA will cover progress of the hypothetical impact scenario from 29 April to 3 May live via social media, primarily via the @esaoperations Twitter channel.


Planetary Defence Conference


The exercise is being produced by experts from NASA’s Planetary Defense Coordination Office working together with the US Federal Emergency Management Agency at the 2019 Planetary Defense Conference, Washington DC. The conference is the world’s most important gathering of asteroid experts, and is strongly supported by ESA, NASA and other agencies, organisations and scientific institutions.


“The first step in protecting our planet is knowing what’s out there,” says Rüdiger Jehn, ESA’s Head of Planetary Defence.



ESA’s Flyeye telescope is now being built in Italy

“Only then, with enough warning, can we take the steps needed to prevent an asteroid strike altogether, or to minimise the damage it does on the ground.”


20’000 asteroid milestone


As of April 2019, 20 000 asteroids whose orbit brings them near Earth have been found. At the current rate of roughly 150 new discoveries every month, this number is set to rapidly increase.


With the planned deployments of ESA’s new Flyeye and Test-Bed Telescopes, Europe’s ability to discover, confirm and understand the ancient rocks that hurtle through space will grow – fundamental to implementing mitigation measures.


Follow asteroid impact exercise live


The @esaoperations Twitter channel will share updates on the asteroid impact exercise in realtime, including daily press releases revealing how the asteroid impact scenario will evolve, so followers will find out the ‘news’ as the experts do.


What will they do? What would you do?


On ESA Facebook, join us for two live-stream videos straight from the Planetary Defense Conference. The first will be on Sunday, 28 April, at 14:00 CEST (08:00 EDT) with Rüdiger Jehn, ESA’s Head of Planetary Defence, and the second on Thursday, 2 May, at around mid-afternoon European time.



Estimated risk corridor for the impact of a hypothetical asteroid

For daily updates on the asteroid impact scenario, check out “Rolling coverage: Brace for hypothetical asteroid impact”, beginning on the first day of the conference, Monday, 29 April, over on ESA’s Rocket Science blog.


Hypothetical impact


Follow ESA’s first-ever live coverage of a hypothetical asteroid impact exercise from the international Planetary Defense Conference
http://blogs.esa.int/rocketscience/2019/04/25/rolling-coverage-brace-for-hypothetical-asteroid-impact/


Asteroid 2019 PDC hypothetical impact scenario


The scene has been set for this year’s hypothetical impact scenario. Although realistic, it is completely fictional and does not describe an actual asteroid impact.


— An asteroid was discovered on 26 March 2019 and was given the name ‘2019 PDC’ by the Minor Planet Center.


— Very little is known about this newly discovered asteroid’s physical properties. With a magnitude (brightness) of 21.1 – invisible to the naked eye but viewable by professional astronomers – it has been classed as a ‘Potentially Hazardous Asteroid’, and experts have determined its average size could be anywhere from 100-300 metres.


— The day after 2019 PDC was discovered, ESA and NASA’s ‘impact monitoring systems’ identified several future dates when the asteroid could hit Earth. At this early stage, with not many observations yet recorded, both systems agreed that the asteroid was most likely to strike on 29 April 2027 – more than eight years away – with a probability of impact of about 1 in 50 000.


— Astronomers continued to monitor the asteroid for a month after its initial detection, which provided them more information about the object’s trajectory, and have now discovered that the chance of impact is rapidly increasing. By 29 April 2019, (the first day of the Planetary Defence Conference), the probability of impact has risen to 1 in 100.


ESA coordinates European efforts


The 2019 Planetary Defence Conference will be the sixth such conference that the International Academy of Astronautics (IAA) has held; and ESA has been closely involved with all of them.



ESA’s planned Hera mission will test asteroid deflection techniques

As in previous years, ESA is sponsoring the event and providing a conference co-chair. A large team of ESA experts will also be present, including members of the Agency’s Near-Earth Object Coordination Centre and the Hera asteroid deflection mission.


During the hypothetical asteroid impact scenario, ESA experts will participate in discussions on the possible risks posed by asteroid 2019 PDC, and what responses could be considered.


“Fortunately, impacts from medium and large asteroids are not very common,” explains Detlef Koschny, senior asteroid expert at ESA who will be involved in the hypothetical scenario.”


“However, this means we have little opportunity to practise our response to this very real – though unlikely – danger. This year’s impact scenario is a very unique chance to run through, in real-time, an asteroid impact.”


Space Safety at ESA


Solar activity, asteroids and artificial space debris all pose threats to our planet and our use of space.



Space Safety & Security at ESA

ESA’s Space Safety activities aim to safeguard society and the critical satellites on which we depend, identifying and mitigating threats from space through projects such as the Flyeye telescopes, the Lagrange space weather mission and the Hera asteroid mission.


As asteroid experts meet for the international Planetary Defense Conference, ESA is focusing on the threat we face from space rocks. How likely is an asteroid impact? What is ESA doing to mitigate impact risks? Follow the hashtag #PlanetaryDefense to find out more.


Related article:


NASA, FEMA, International Partners Plan Asteroid Impact Exercise
https://orbiterchspacenews.blogspot.com/2019/04/nasa-fema-international-partners-plan.html
 
Related links:


@esaoperations Twitter channel: http://www.twitter.com/esaoperations


ESA Facebook: http://www.facebook.com/europeanspaceagency


NASA’s Planetary Defense Coordination Office: https://www.nasa.gov/feature/nasa-fema-international-partners-plan-asteroid-impact-exercise


2019 Planetary Defense Conference: http://pdc.iaaweb.org/


ESA’s Rocket Science blog: http://blogs.esa.int/rocketscience


Near-Earth Object Coordination Centre: http://neo.ssa.esa.int/


Hera asteroid deflection mission: http://www.esa.int/Our_Activities/Operations/Space_Safety_Security/Hera


#PlanetaryDefense: https://twitter.com/search?l=&q=%23PlanetaryDefense&src=typd


Images, Video, Text, Credits: European Space Agency (ESA)/A. Baker, CC BY-SA 3.0 IGO/ScienceOffice.org.


Greetings, Orbiter.chArchive link


Antarctica’s Effect on Sea Level Rise in Coming Centuries


JPL — Jet Propulsion Laboratory logo.


April 26, 2019


There are two primary causes of global mean sea level rise — added water from melting ice sheets and glaciers, and the expansion of sea water as it warms. The melting of Antarctica’s ice sheet is currently responsible for 20-25% of global sea level rise.


But how much of a role will it play hundreds of years in the future?


Scientists rely on precise numerical models to answer questions like this one. As the models used in predicting long-term sea level rise improve, so too do the projections derived from them. Scientists at NASA’s Jet Propulsion Laboratory in Pasadena, California, have discovered a way to make current models more accurate. In doing so, they have also gotten one step closer to understanding what Antarctica’s ice sheet — and the sea level rise that occurs as it melts — will look like centuries from now.



Thwaites Glacier. Image Credits: NASA/James Yungel

«Unlike most current models, we included solid Earth processes — such as the elastic rebound of the bedrock under the ice, and the impact of changes in sea level very close to the ice sheet,» said JPL’s Eric Larour, first author of the study. «We also examined these models at a much higher resolution than is typically used — we zoomed in on areas of bedrock that were about 1 kilometer instead of the usual 20 kilometers.»


The scientists found that projections for the next 100 years are within 1% of previous projections for that time period; however, further into the future, they observed some significant differences.


«We found that around the year 2250, some of these solid Earth processes started to offset the melting of the ice sheet and the consequent sea level rise,» Larour said. In other words, they actually slowed the melting down.


The team noted that a hundred years even further into the future — by 2350 — this slowdown means that the melting of the ice sheet is likely to contribute 29% less to global sea level rise than previous models indicated.



Animation above: This animation shows projections of ice sheet retreat in Antarctica over 500 years using the previous models (shown in green) and the new models, which take into account solid Earth processes like the elastic rebound of the Earth (shown in red). The new models show that by the year 2350, melting of the ice sheet and its corresponding contribution to sea-level rise will be about 29% less than what previous projections had indicated for this distant time period. Animation Credits: NASA/JPL-Caltech.


«One of the main things we learned was that as grounded ice retreats inland, the bedrock under it lifts up elastically,» said Erik Ivins, a co-author of the study. «It’s similar to how a sofa cushion decompresses when you remove your weight from it. This process slows down the retreat of the ice sheet and ultimately the amount of melting.»


Although this sounds like good news, the scientists say it’s important to keep it in perspective. «It’s like a truck traveling downhill that encounters speed bumps in the road,» said Larour. «The truck will slow down a bit but will ultimately continue down the hill» — just as the ice sheet will continue to melt and sea level will continue to rise.


The breakthrough of this study, he added, was to «reach resolutions high enough to capture as many of these ‘speed bumps’ as possible and determine their effects in Antarctica while also modeling sea level rise over the entire planet.»


The study, titled «Slowdown in Antarctic Mass Loss from Solid Earth and Sea-Level Feedback,» was published today in Science.


More information on the study can be found at: https://vesl.jpl.nasa.gov/sea-level/slr-uplift


Image (mentioned), Animation (mentioned), Text, Credits: NASA/JPL/Esprit Smith.


Greetings, Orbiter.chArchive link


Successful Operation of Asteroid Explorer Hayabusa2’s SCI


JAXA — Hayabusa2 Mission patch.


April 26, 2019


Japan Aerospace Exploration Agency (JAXA) separated the SCI (Small Carry-on Impactor), which had been onboard the asteroid explorer Hayabusa2, on April 5, 2019, for deployment to Ryugu, and then put the SCI into operation.


As a result of checking the images captured by the Optical Navigation Camera — Telescopic (ONC-T) onboard the asteroid explorer Hayabusa2, we have concluded that a crater was created by the SCI.


Hayabusa2 is operating normally.



Images above: Images taken by the ONC-T; Left image: Taken on March 22, 2019; Right image: Taken on April 25, 2019; (Onboard date, JST).


These images were captured by the Optical Navigation Camera — Telescopic onboard Hayabusa2. By comparing the two images, we have confirmed that an artificial crater was created in the area surrounded by dotted lines. The size and depth of the crater are now under analysis.


Image credit: JAXA, The University of Tokyo, Kochi University, Rikkyo University, Nagoya University, Chiba Institute of Technology, Meiji University, The University of Aizu, AIST.


Related article:


Asteroid Explorer Hayabusa2’s Science — Put into Operation
https://orbiterchspacenews.blogspot.com/2019/04/asteroid-explorer-hayabusa2s-science.html


Related links:


Hayabusa2 Asteroid Probe (ISAS): http://www.isas.jaxa.jp/en/missions/spacecraft/current/hayabusa2.html


Asteroid Explorer «Hayabusa2»: http://global.jaxa.jp/projects/sas/hayabusa2/index.html


Images (mentioned), Text, Credits: Japan Aerospace Exploration Agency (JAXA)/National Research and Development Agency.


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Wiring for Locomotion Our reflexes are what keep us alive when…


Wiring for Locomotion


Our reflexes are what keep us alive when we are first brought into the world. As we grow, and the connections that form between cells in our brain and spinal cord become more complex, we acquire more advanced behaviours. Scientists have recently studied how these neuronal circuits develop in zebrafish, which grow into adults just days after birth. Using time-lapse technology, the team found that different circuits are built one on top another, from 24 hours before birth (from above and side, first column) to three days after birth (fifth column). Each circuit dictates different types of movements, with the ones built a day after birth controlling whole-body reflex movements that help the young fish swim away from predators, and those built three days after birth controlling slower, more refined movements. Understanding this relationship between neuronal connections and behaviour may one day lead to treatments that can repair circuits damaged by injury or disease.


Written by Gaëlle Coullon



You can also follow BPoD on Instagram, Twitter and Facebook


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Earth: Our Oasis in Space

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Earth: It’s our oasis in space, the one place we know that harbors life. That makes it a weird place – so far, we haven’t found life anywhere else in the solar system…or beyond. We study our home planet and its delicate balance of water, atmosphere and comfortable temperatures from space, the air, the ocean and the ground.


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To celebrate our home, we want to see what you love about our planet. Share a picture, or several, of Earth with #PictureEarth on social media. In return, we’ll share some of our best views of our home, like this one taken from a million miles away by the Earth Polychromatic Imaging Camera (yes, it’s EPIC).


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From a DC-8 research plane flying just 1500 feet above Antarctic sea ice, we saw a massive iceberg newly calved off Pine Island Glacier. This is one in a series of large icebergs Pine Island has lost in the last few years – the glacier is one of the fastest melting in Antarctica.


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It’s not just planes. We also saw the giant iceberg, known as B-46, from space. Landsat 8 tracked B-46’s progress after it broke off from Pine Island Glacier and began the journey northward, where it began to break apart and melt into the ocean.


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Speaking of change, we’ve been launching Earth-observing satellites since 1958. In that time, we’ve seen some major changes. Cutting through soft, sandy soil on its journey to the Bay of Bengal, the Padma River in Bangladesh dances across the landscape in this time-lapse of 30 years’ worth of Landsat images.  


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Our space-based view of Earth helps us track other natural activities, too. With both a daytime and nighttime view, the Aqua satellite and the Suomi NPP satellite helped us see where wildfires were burning in California, while also tracking burn scars and smoke plumes..


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Astronauts have an out-of-this-world view of Earth, literally. A camera mounted on the International Space Station captured this image of Hurricane Florence after it intensified to Category 4.


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It’s not just missions studying Earth that capture views of our home planet. Parker Solar Probe turned back and looked at our home planet while en route to the Sun. Earth is the bright, round object.



Want to learn more about our home planet? Check out our third episode of NASA Science Live where we talked about Earth and what makes it so weird. 


Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com


Smoky Quartz with Fluorite | #Geology #GeologyPage…


Smoky Quartz with Fluorite | #Geology #GeologyPage #Mineral


Locality: Zinggenstock, Grimsel area, Hasli valley, Berner Oberland, Switzerland


Size: 9.6 x 8 x 4 cm


Photo Copyright © Saphira Minerals


Geology Page

www.geologypage.com

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Scientists create largest collection of coral reef maps ever made

A study from scientists at the Khaled bin Sultan Living Oceans Foundation and the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science offers a new way to accurately map coral reefs using a combination of Earth-orbiting satellites and field observations. This first-ever global coral reef atlas contains maps of over 65,000 square kilometers (25,097 square miles) of coral reefs and surrounding habitats.











Scientists create largest collection of coral reef maps ever made
Viewing coral reefs from above reveals much about their health and structure. Repeated observations through
 time can be used to track change. Regional-scale reef mapping is a key precursor for conservation 
of this imperiled ecosystem [Credit: Khaled bin Sultan Living Oceans Foundation]

The maps, published in the journal Coral Reefs, are the result of a 10-year Global Reef Expedition by scientists for the Khaled bin Sultan Living Oceans Foundation. The expedition traveled to over 1,000 remote coral reefs in 15 countries, mapping and surveying the reefs down to a one-square meter scale to better understand their health and resiliency. Many of the reefs visited on the expedition had never been studied before.


The high-resolution coral reef maps contain information on shallow water marine habitat such as fore and back reefs as well as information on the size of seagrass beds and mangrove forests for key locations visited on the expedition. All of these coastal habitats are key components of tropical coastal ecosystems and help to filter water, protect the coast from storms, and provide key nursery habitat for commercial and subsistence fisheries. They also face increasing threats from coastal development, overfishing, and climate change.


To develop the new model to accurately map coral reef and other tropical shallow-water marine habitats, scientists took data collected from extensive SCUBA surveys conducted on the Global Reef Expedition and extrapolate that information across the entire reef using ultra-high-resolution satellite imagery. By comparing the maps with video footage from cameras dropped at precise coordinates along the reef, the scientists were able to verify the accuracy of their new mapping method.


«In order to conserve something, it’s imperative to know where it is located and how much of it you have,» said Sam Purkis, professor and chair of the UM Rosenstiel School Department of Marine Geosciences. «Developing such an understanding for coral reefs is especially challenging because they are submerged underwater and therefore obscured from casual view. With this study, we demonstrate the potential to use satellite images to make coral reef maps at global scale.»


Scientists now have a way to peer beneath the waves to accurately map large areas of coral reefs at greatly reduced cost. Traditional coral reef surveys are expensive to conduct and limited in scope, requiring hours of underwater surveys conducted by highly-trained scientific divers. Using this new model, scientists can create detailed coral reef habitat maps at a regional scale without having to survey the entire reef in person.


«Satellite, aircraft, and drone imaging will become an increasingly important tool for addressing the coral reef crisis at the global scale at which it’s occurring.» said Purkis, also the interim chief scientist for the Living Oceans Foundation.


The high-resolution coral reef maps made for this study can be found on the World Reef Map, an interactive coral reef atlas where users can explore all of the coral reefs and shallow water marine habitats mapped on the Global Reef Expedition.


Although they by no means cover every reef worldwide, this new atlas covers a meaningful portion of key reef provinces around the world. It also provides much-needed baseline data of coral reef health prior to the 2017 mass bleaching event. This digital resource has been made available to the public so that governments and conservation organizations can use these maps to protect and restore their coral reefs for generations to come.


Scientists estimate that over 50 percent of coral reefs worldwide have been lost in the past 40 years due to climate change and other human pressures. These new detailed habitat maps can help local resource managers identify areas that may be in greatest need of conservation action.


«Benthic habitat maps are an essential tool in coral reef conservation as they provide a snapshot of where reefs are located and the status of their health,» said Alexandra Dempsey, the director of science management for the Khaled bin Sultan Living Oceans Foundation and a co-author of the paper. «Scientists will use these habitat maps as baseline data to help track changes in reef composition and structure over time.»


Source: University of Miami Rosenstiel School of Marine & Atmospheric Science [April 23, 2019]



TANN



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One million species risk extinction due to humans: Draft UN report

Up to one million species face extinction due to human influence, according to a draft UN report that painstakingly catalogues how humanity has undermined the natural resources upon which its very survival depends.











One million species risk extinction due to humans: Draft UN report
Experts say up to a million species face extinction — some within decades — from human activity including habitat loss,
 over-consumption and illegal poaching [Credit: Wikus De Wet/AFP]

The accelerating loss of clean air, drinkable water, CO2-absorbing forests, pollinating insects, protein-rich fish and storm-blocking mangroves — to name but a few of the dwindling services rendered by Nature — poses no less of a threat than climate change, says the report, set to be unveiled on May 6.
Indeed, biodiversity loss and global warming are closely linked, according to the 44-page Summary for Policy Makers, which distills a 1,800-page UN assessment of scientific literature on the state of Nature.


Delegates from 130 nations meeting in Paris from April 29 will vet the executive summary line by line. Wording may change, but figures lifted from the underlying report cannot be altered.











One million species risk extinction due to humans: Draft UN report
The report finds that three-quarters of land surfaces have been ‘severely altered’ by mankind
including through deforestation [Credit: Mohd Rasfan/AFP]

«We need to recognise that climate change and loss of Nature are equally important, not just for the environment, but as development and economic issues as well,» Robert Watson, chair of the UN-mandated body that compiled the report, told Agence France-Presse, without divulging its findings.


«The way we produce our food and energy is undermining the regulating services that we get from Nature,» he said, adding that only «transformative change» can stem the damage.


Deforestation and agriculture, including livestock production, account for about a quarter of greenhouse gas emissions, and have wreaked havoc on natural ecosystems as well.


Mass extinction event


The Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) report warns of «an imminent rapid acceleration in the global rate of species extinction.»











One million species risk extinction due to humans: Draft UN report
Insect populations are declining steeply worldwide, further pressuring foodchains
[Credit: Yuri Kadobnov/AFP]

The pace of loss «is already tens to hundreds of times higher than it has been, on average, over the last 10 million years,» it notes.


«Half-a-million to a million species are projected to be threatened with extinction, many within decades.»


Many experts think a so-called «mass extinction event»—only the sixth in the last half-billion years—is already under way.


The most recent saw the end of the Cretaceous period some 66 million years ago, when a 10-kilometre-wide asteroid strike wiped out most lifeforms.











One million species risk extinction due to humans: Draft UN report
Biodiversity loss around the world measured in percentage compared to an intact ecosystem
[Credit: Simon Malfatto/AFP]

Scientists estimate that Earth is today home to some eight million distinct species, a majority of them insects.


A quarter of catalogued animal and plant species are already being crowded, eaten or poisoned out of existence.


The drop in sheer numbers is even more dramatic, with wild mammal biomass—their collective weight—down by 82 percent.


Humans and livestock account for more than 95 percent of mammal biomass.


Population growth


«If we’re going to have a sustainable planet that provides services to communities around the world, we need to change this trajectory in the next ten years, just as we need to do that with climate,» noted WWF chief scientist Rebecca Shaw, formerly a member of the UN scientific bodies for both climate and biodiversity.


The direct causes of species loss, in order of importance, are shrinking habitat and land-use change, hunting for food or illicit trade in body parts, climate change, pollution, and alien species such as rats, mosquitoes and snakes that hitch rides on ships or planes, the report finds.


«There are also two big indirect drivers of biodiversity loss and climate change—the number of people in the world and their growing ability to consume,» said Watson.



Once seen as primarily a future threat to animal and plant life, the disruptive impact of global warming has accelerated.
Shifts in the distribution of species, for example, will likely double if average temperature go up a notch from 1.5 degrees Celsius (2.7 Fahrenheit) to 2C.


So far, the global thermometer has risen 1C compared with mid-19th century levels.


The 2015 Paris Agreement enjoins nations to cap the rise to «well below» 2C. But a landmark UN climate report in October said that would still be enough to boost the intensity and frequency of deadly heatwaves, droughts, floods and storms.


Global inequity


Other findings in the report include:


— Three-quarters of land surfaces, 40 percent of the marine environment, and 50 percent of inland waterways across the globe have been «severely altered».


— Many of the areas where Nature’s contribution to human wellbeing will be most severely compromised are home to indigenous peoples and the world’s poorest communities that are also vulnerable to climate change.


— More than two billion people rely on wood fuel for energy, four billion rely on natural medicines, and more than 75 percent of global food crops require animal pollination.


— Nearly half of land and marine ecosystems have been profoundly compromised by human interference in the last 50 years.


— Subsidies to fisheries, industrial agriculture, livestock raising, forestry, mining and the production of biofuel or fossil fuel energy encourage waste, inefficiency and over-consumption.


The report cautioned against climate change solutions that may inadvertently harm Nature.


The use, for example, of biofuels combined with «carbon capture and storage»—the sequestration of CO2 released when biofuels are burned—is widely seen as key in the transition to green energy on a global scale.


But the land needed to grow all those biofuel crops may wind up cutting into food production, the expansion of protected areas or reforestation efforts.


Author: Marlowe Hood | Source: AFP [April 23, 2019]



TANN



Archive


Why unique finches keep their heads of many colours

There appears to be an underlying selection mechanism at work among Gouldian Finches—a mechanism that allows this species to produce and maintain individuals with red heads, black heads, and yellow heads. Research by scientists from the the University of Sheffield in the United Kingdom, the Cornell Lab of Ornithology, and other institutions, reveals what this additional evolutionary process might be. Findings were published in the journal Nature Communications.











Why unique finches keep their heads of many colours
Red-headed Gouldian finch [Credit: Marc Gardner, 2019]

«Most people have heard of natural selection,» says lead author Kang-Wook Kim at the University of Sheffield. «But ‘survival of the fittest’ cannot explain the colour diversity we see in the Gouldian Finch. We demonstrate that there is another evolutionary process—balancing selection—that has maintained the black or red head colour over thousands of generations.»
The yellow-headed type (actually more orange) is produced by a completely different mechanism that is not yet understood. Yellow-headed Gouldian Finches make up less than one percent of the wild population.


«Having distinct multiple colour types—a polymorphism—maintained within a species for a long time is extremely rare,» explains co-author David Toews, who did this work as a postdoctoral researcher at the Cornell Lab and who is now at Pennsylvania State University. «Natural selection is typically thought of in a linear fashion—a mutation changes a trait which then confers some reproductive or survival advantage, which results in more offspring, and the trait eventually becomes the sole type in the population.»











Why unique finches keep their heads of many colours
Black-headed Gouldian finch [Credit: Marc Gardner, 2019]

Studies from Macquarie University in Australia have shown the red-headed finches have the apparent advantage. Female Gouldian Finches of all colours prefer the red-headed males, who also happen to be more dominant in the social hierarchy. So why hasn’t the black-headed type disappeared? It turns out there are disadvantages to having a red head, too, such as higher levels of stress hormones in competitive situations.
«If advantages are cancelled out by concurrent disadvantages, these two colour types can be maintained—that’s balancing selection,» Toews says. «Red forms are not as common in the wild, so the counterbalancing pressure reduces the advantage of being red. That’s super cool!»


Teams from the University of Sheffield and the Cornell Lab independently zeroed in on a particular gene called follistatin which is found on the Gouldian Finch sex chromosome and regulates melanin to produce either red- or black-headed finches. Rather than competing, the two teams decided to join forces and share their data. For the yellow morph, a different gene, not located on the sex chromosome, is controlling the head pigmentation, but it hasn’t yet been found and it’s not clear what forces are allowing the yellow morph to persist in the wild.











Why unique finches keep their heads of many colours
Graphic shows the location of genes that control head colour in Gouldian finches
[Credit: Graphic by Bartels Science Illustrator Megan Bishop,
Cornell Lab of Ornithology]

In another twist, Toews and co-author Scott Taylor, at the University of Colorado-Boulder, have done previous research that revealed the genes likely governing the plumage differences between North American Blue-winged and Golden-winged Warblers—and one of those regions is in the same spot on the sex chromosome that differs among Gouldian Finches with different head colours.


«We didn’t expect we’d locate the exact genomic region that governs plumage differences in both the Gouldian Finch and the two warblers,» says Toews. «But now that we’ve done it, it opens up the possibility that the same region in other species may also be controlling plumage colour.»


Source: Cornell University [April 23, 2019]



TANN



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2019 April 26 Southern Cross to Eta Carinae Image Credit &…


2019 April 26


Southern Cross to Eta Carinae
Image Credit & Copyright: Carlos Fairbairn


Explanation: Tracking along the southern Milky Way this beautiful celestial mosaic was recorded under dark Brazilian skies. Spanning some 20 degrees it actually starts with the dark expanse of the Coalsack nebula at the lower left, tucked under an arm of the Southern Cross. That compact constellation is topped by bright yellowish Gamma Crucis, a cool giant star a mere 88 light-years distant. A line from Gamma Crucis through the blue star at the bottom of the cross, Alpha Crucis, points toward the South Celestial Pole. Follow the Milky Way to the right and your gaze will sweep across IC 2948, popularly known as the Running Chicken nebula, before it reaches Eta Carinae and the Carina Nebula near the right edge of the frame. About 200 light-years across, the Carina Nebula is a star forming region much larger than the more northerly stellar nursery the Orion Nebula. The Carina Nebula lies around 7,500 light-years from Earth along the plane of the Milky Way.


∞ Source: apod.nasa.gov/apod/ap190426.html


The Giant Galaxy Around the Giant Black Hole


The galaxy M87, imaged here by NASA’s Spitzer Space Telescope, is home to a supermassive black hole that spews two jets of material out into space at nearly the speed of light. The inset shows a close-up view of the shockwaves created by the two jets.Credit: NASA/JPL-Caltech/IPAC. Full image and caption



The galaxy M87 looks like a hazy, blue space-puff in this image from NASA’s Spitzer Space Telescope. At the galaxy’s center is a supermassive black hole that spews two jets of material out into space. Credit: NASA/JPL-Caltech/IPAC. Hi-res image



This wide-field image of the galaxy M87 was taken by NASA’s Spitzer Space Telescope. The top inset shows a close-up of two shockwaves, created by a jet emanating from the galaxy’s supermassive black hole. The Event Horizon Telescope recently took a close-up image of the silhouette of that black hole, show in the second inset.Credit: NASA/JPL-Caltech/Event Horizon Telescope Collaboration. Hi-res image




On April 10, 2019, the Event Horizon Telescope (EHT) unveiled the first-ever image of a black hole’s event horizon, the area beyond which light cannot escape the immense gravity of the black hole. That giant black hole, with a mass of 6.5 billion Suns, is located in the elliptical galaxy Messier 87 (M87). EHT is an international collaboration whose support in the U.S. includes the National Science Foundation.


This image from NASA’s Spitzer Space Telescope shows the entire M87 galaxy in infrared light. The EHT image, by contrast, relied on light in radio wavelengths and showed the black hole’s shadow against the backdrop of high-energy material around it.


Located about 55 million light-years from Earth, M87 has been a subject of astronomical study for more than 100 years and has been imaged by many NASA observatories, including the Hubble Space Telescope, the Chandra X-ray Observatoryand NuSTAR. In 1918, astronomer Heber Curtis first noticed «a curious straight ray» extending from the galaxy’s center. This bright jet of high-energy material, produced by a disk of material spinning rapidly around the black hole, is visible in multiple wavelengths of light, from radio waves through X-rays. When the particles in the jet impact the interstellar medium (the sparse material filling the space between stars in M87), they create a shockwave that radiates in infrared and radio wavelengths of light but not visible light. In the Spitzer image, the shockwave is more prominent than the jet itself.


The brighter jet, located to the right of the galaxy’s center, is traveling almost directly toward Earth. Its brightness is amplified due to its high speed in our direction, but even more so because of what scientists call «relativistic effects,» which arise because the material in the jet is traveling near the speed of light. The jet’s trajectory is just slightly offset from our line of sight with respect to the galaxy, so we can still see some of the length of the jet. The shockwave begins around the point where the jet appears to curve down, highlighting the regions where the fast-moving particles are colliding with gas in the galaxy and slowing down.


The second jet, by contrast, is moving so rapidly away from us that the relativistic effects render it invisible at all wavelengths. But the shockwave it creates in the interstellar medium can still be seen here.


Located on the left side of the galaxy’s center, the shockwave looks like an inverted letter «C.» While not visible in optical images, the lobe can also be seen in radio waves, as in this imagefrom the National Radio Astronomy Observatory’s Very Large Array.


By combining observations in the infrared, radio waves, visible light, X-rays and extremely energetic gamma rays, scientists can study the physics of these powerful jets. Scientists are still striving for a solid theoretical understanding of how gas being pulled into black holes creates outflowing jets.


Infrared light at wavelengths of 3.4 and 4.5 microns are rendered in blue and green, showing the distribution of stars, while dust features that glow brightly at 8.0 microns are shown in red. The image was taken during Spitzer’s initial «cold» mission.


The Jet Propulsion Laboratory in Pasadena, California, manages the Spitzer Space Telescope mission for NASA’s Science Mission Directorate in Washington. Science operations are conducted at the Spitzer Science Center at Caltech in Pasadena. Space operations are based at Lockheed Martin Space Systems in Littleton, Colorado. Data are archived at the Infrared Science Archive housed at IPAC at Caltech. Caltech manages JPL for NASA.



More information on Spitzer can be found at its website:  http://www.spitzer.caltech.edu/


News Media Contact


Calla Cofield
Jet Propulsion Laboratory, Pasadena, Calif.
626-808-2469

calla.e.cofield@jpl.nasa.gov






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Holocene changes of landforms and environments in the eastern portion of Asian...

Deserts belong to the most beautiful landforms on Earth although their potential encroachments may threaten daily lives of many people, in particular those in developing countries. Studies of past environmental changes in deserts are of great significance for understanding the nature of arid ecosystems and for establishing effective strategies to overcome the threat of desertification to the global communities in the 21st Century.











Holocene changes of landforms and environments in the eastern portion of Asian mid-latitude deserts
Location of study area. (A) Overview of the drylands in north China. The Gonghe Basin is located in the
 marginal zone influenced by the Asian summer monsoon. The modern Asian summer monsoon limit is
indicated by a dark dashed line redrawn from Gao et al. (1962). (B) The Gonghe Basin (Google Earth™),
with locations of the studied aeolian sections and the Lagan (LG) section (Liu et al., 2013)
indicated by solid blue squares [Mingrui Qiang et al. 2016]

The remains of paleo-landforms and sedimentary sections in deserts allow scientists to reconstruct phases of aeolian activity or occurrence of sand dunes, and the state and timing of environmental stability due to the increase in vegetation coverage. Because of extreme sensitivities of desert ecosystem, the study of deserts can help scientists better identify not only the nature and history of deserts but also the variability of climate system on Earth.


Sand seas dominated by active sand dunes, the most common landforms in deserts, are widely distributed in the arid regions of northern China with a mean annual precipitation less than 200 mm, while the sandy lands characterized with semi-fixed and vegetated (at least partly) dunes mainly occur in the semi-arid regions with a mean annual precipitation of 200-400 mm in the mid-latitudes of Asia. The spatial and temporal variations of these vegetated and active dunes provide clues to decipher changes of global climate systems, human activities and the interactions between natural and human factors.


Based on careful field investigation over decades and geochronological and paleoenvironmental data, Professor Xiaoping Yang of Zhejiang University in Hangzhou and his collaborators from several institutions jointly studied the Holocene histories of the sand seas and sandy lands in the eastern portion of the desert belt in northern China.


Their results show that spatial and temporal heterogeneity has been common in the dune fields of northern China. They demonstrated that it is a must to obtain more than a few sedimentary records in order to correctly reconstruct palaeoclimatic histories in the arid and semi-arid areas with diverse landforms like those in northern China.











Holocene changes of landforms and environments in the eastern portion of Asian mid-latitude deserts
Photographs of the studied aeolian sections [Mingrui Qiang et al. 2016]

One of the difficulties in interpreting paleoenvironmental histories in deserts is that new phase of aeolian activities might be just a reworking of previously deposited sediments from an existing dune system, resulting in a lower probability of preserving older deposits, a potentially large gap in the palaeoenvironmental records. Even though, the team is able to have recognized periods of environmentally stable conditions in the eastern portion of the desert belt in northern China on the basis of large number of new data.


On the contrary to the earlier doctrine of millions of years in age, the new study shows that the sand seas and sandy lands in the eastern portion of the desert belt in northern China is very vulnerable to climate changes and to human activities. The current Kubuqi Sand Sea, the only sand sea in the semi-arid regions of China, has been formed during the Holocene, partly due to agricultural cultivation in historical times.


A long-lasting, although not equally long, stabilization of aeolian landforms had occurred almost in every sandy land in northern China during the middle Holocene according to their studies. The team emphasized that dune activities cannot simply be considered as an indicator of climate aridity as done in some early projects. Due to strong interactions between aeolian, fluvial and lacustrine processes in these sandy lands, the study areas provide an ideal laboratory for understanding Earth surface processes and Earth system.


Such kind of studies may help decision-makers establish ecologically sustainable land use strategies. These research results have just been published online in the journal Science China Earth Sciences under the title «Holocene aeolian stratigraphic sequences in the eastern portion of the desert belt (sand seas and sandy lands) in northern China and their palaeoenvironmental implications».


Source: Science China Press [April 23, 2019]



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The population history of the last hunter-gatherers of the Iberian Peninsula

The scientific journal Nature Communications is publishing a new study today about the demographic dynamics of the last populations of hunter-gatherers that inhabited the Iberian Peninsula between 18.000 to 8.000 years ago.











The population history of the last hunter-gatherers of the Iberian Peninsula
Distribution of archaeological sites with radiocarbon dates analyzed in this study.
The colours represent the different regional subsets analyzed
[Credit: IPHES]

This period, known as the Pleistocene-Holocene Transition, is characterised by extreme changes in climatic and environmental conditions whose impact on prehistoric societies has been debated for decades.


The paper analyses the whole radiocarbon record of the Iberian Peninsula for this period, conducting thousands of computational simulations to compare the goodness of fit of different demographic models. Therefore, three different demographic phases have been identified for this period.


First, during the end of the last glacial cycle, between 16.600 and 12.700 years ago, the population grew exponentially.


In contrast, between 12.700 and 10.200 years ago, during the cold episode of the Younger Dryas and the rapid warming of Early Holocene onset, authors find a sustained phase of population contraction and stabilisation.


 Finally, at third demographic phase is identified between 10.200 and 8.000 years ago, during the Mesolithic period, with a rapid population increase followed by stabilisation under a new demographic threshold.


The results show that prehistoric foragers had an inherent capacity for rapid demographic growth, but this was checked by the constraints of the environment, especially during periods of climate change.


Source: Institut Català de Paleoecologia Humana i Evolució Social (IPHES) [April 23, 2019]



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Replica of part of destroyed Palmyra altar unveiled in Syria

A Damascus museum on Tuesday unveiled a replica, built by Italian archaeologists, of part of a temple altar destroyed by Islamic State militants in the ancient Syrian city of Palmyra.











Replica of part of destroyed Palmyra altar unveiled in Syria
A replica of an altar ceiling from the Temple of Bel is exhibited at Syria’s National Museum of Damascus
[Credit: Yamam Alshaar]

The 2,000-year-old Temple of Bel at Palmyra was one of the jewels in Syria’s lavish trove of historical monuments, spanning myriad civilizations, before the country’s conflict began in 2011.
Islamic State seized Palmyra in May 2015 and demolished many of its ancient structures and objects, while looting others to help finance its operations.











Replica of part of destroyed Palmyra altar unveiled in Syria
A replica of an altar ceiling from the Temple of Bel is exhibited at Syria’s National Museum of Damascus
[Credit: Yamam Alshaar]

The temple’s ornate stone altar structure was destroyed in October 2015, but an Italian team has rebuilt its ceiling using 3D imaging and skilled stonework.
“It is identical to the original piece with all its details and decorations because the 3D technique is very developed,” said Mamoun Abdul Karim, the former head of the Syrian government’s antiquities department. “But it is no substitute for the original object,” he added.











Replica of part of destroyed Palmyra altar unveiled in Syria
A view of a 3D-printed model of a section of the roof of the Palmyrene Temple of Bel
[Credit: AFP]

The new altar is 4 meters long and built with a combination of plastic and polished stone, said Frances Pinnock of the Sapienza University of Rome, head of the scientific team that worked on the building process.
She said they had proposed building a replica as an emotional response to the destruction of the ceiling, but also to see if it was scientifically possible to construct what was lost.



Abdul Karim called on the international community to make the same effort to restore Syria’s Palmyra as it is making for Notre Dame Cathedral in Paris, damaged in a fire last week.


“It is an international responsibility,” he said.


Source: Reuters [April 23, 2019]



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A Neanderthal tooth discovered in Serbia reveals human migration history

In 2015, our Serbian-Canadian archaeological research team was working at a cave site named Pešturina, in Eastern Serbia, where we had found thousands of stone tools and animal bones. One day, an excited Serbian undergrad brought us a fossil they had uncovered: a small molar tooth, which we immediately recognized as human.











A Neanderthal tooth discovered in Serbia reveals human migration history
A 3D recreation of a recently discovered Neanderthal tooth
[Credit: Joshua Lindal]

A single tooth may not seem like much, but a lot of information can be drawn from it. We knew it was about 100,000 years old, because the layer it was found in had previously been dated. We were able to build a high-resolution 3D model to study the shape of the crown, roots and internal structure. We made detailed measurements and performed statistical analyses which are published in the June 2019 issue of the Journal of Human Evolution.
The results of our analysis are clear: our little tooth belonged to a Neanderthal. Neanderthal fossils have been found in Croatia and Greece, but they are still relatively rare in the Balkans, compared to Western Europe and the Middle East. This is the first Neanderthal ever found in Serbia.


The first Neanderthal from Serbia


The Neanderthals were a group of ancient humans who lived in western Eurasia during the Pleistocene epoch. Their earliest ancestors lived in Spain almost half a million years ago, and their range gradually expanded eastward through Europe and the Levant and as far as Siberia.


But around 100,000 years ago, modern humans (like us) started to migrate out of Africa and into Eurasia. By 40,000 years ago, Neanderthals began to disappear from Europe, retreating westward as modern humans moved in on their territory. And, around 30,000 years ago, the last remaining Neanderthals in Spain died out.



The timing of the Neanderthal demise and the modern human conquest of Europe can’t be a coincidence. Ten years ago, most paleoanthropologists would have told you that our two groups were competitors: Neanderthals were bigger and stronger, but we were smarter, and in the battle for survival in the harsh landscape, brains beat out brawn.


Attitudes quickly changed in 2010 when the Neanderthal genome was sequenced for the first time, and along with it we discovered that all living humans outside of sub-Saharan Africa carry a small amount of Neanderthal DNA. More recently, we’ve discovered that they carried some of our genes too.


This means that, at least some of the time, our two groups were lovers and not fighters. We’ve never found modern human and Neanderthal skeletons together at the same site, so it’s possible these romantic flings were rare exceptions. But we don’t have any clear evidence of violence between the two groups either, so the question remains open.


The crossroads of Europe


The Central Balkans could hold the key to answering these questions. Sitting at the “crossroads of Europe,” the Balkan Peninsula represents the intersection of several important migration corridors. Rivers like the Danube cut paths through mountain ranges, creating highways for migrating animals and people to follow. Modern humans followed these routes when they first migrated into Europe, funnelled through the same valleys the Neanderthals called home.











A Neanderthal tooth discovered in Serbia reveals human migration history
A map showing Pešturina’s location [Credit: Miloš Radonjić]

Pešturina Cave sits along one of these migration routes, in the side of Jelašnica Gorge, facing out towards the great floodplain of the Nišava River near the modern city of Niš. Even though no one had ever found a Neanderthal fossil in Serbia before now, we were pretty sure they lived there because we have found the remains of their culture: the so-called “Mousterian” stone tool tradition. We also know that early modern human migrants made Pešturina their home later on, because we find their unique stone tool traditions as well. This makes Pešturina Cave one of very few sites in Serbia where we know that both groups lived in the same place, albeit at different times.
Unfortunately, we still don’t know very much about the early prehistory of the Central Balkans, despite the long tradition of archaeological research in the region. Twentieth century archaeologists concentrated on early farmers, Roman palaces and Medieval fortresses. Less visible and more difficult to interpret, Palaeolithic archaeology took a back seat, until now.


Filling in the gaps


Led by archaeology professor Dušan Mihailović of Belgrade University and Bojana Mihailović, curator at the National Museum of Serbia, our international team of researchers has been identifying and excavating caves throughout Serbia, trying to fill the gaps in our knowledge of this important region. Along with our coauthor Predrag Radović, our role on the team is to study fossil human remains.











A Neanderthal tooth discovered in Serbia reveals human migration history
Pešturina Cave, where the fossil was found [Credit: Dušan Mihailović]

A decade ago, in a cave not far from Pešturina named Mala Balanica, we found a human jawbone which would later be dated to about half a million years old — the oldest human fossil from the Central Balkans and one of the oldest from Europe. This jawbone did not belong to a Neanderthal, but to an older (and different) kind of human called Homo heidelbergensis. But we expect to find even older remains: human fossils have been dated to 1.8 million years ago in Georgia and to 1.4 million years ago in Spain; the Balkan crossroads lies right in the middle.
Pešturina Cave has also given up other gifts as well. In the same level as the tooth, our team found a cave bear bone with a series of parallel cut marks made by stone tools. They’re not butchery cuts, and it looks like they might have a symbolic purpose. This would be a big deal because until recently, most researchers thought symbolism and artistic expression were uniquely modern human behaviours. This attitude is shifting, since we’ve recently discovered that Neanderthals probably adorned themselves with feathers, talons and shells and even painted their caves.


The tooth from Pešturina is a small but exciting step towards reconstructing the complex prehistory of human migration and cultural contact in the Central Balkans.


In a collaboration between Belgrade University and the University of Winnipeg, we have been able to offer hands-on field experience to Canadian and international students. Through this collaboration, the Central Balkans will continue to give up more and more clues about our early ancestors and their relationship with the mysterious Neanderthals.


Authors: Mirjana Roksandic & Joshua Allan Lindal | Source: The Conversation [April 23, 2019]



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What the vibrant pigments of bird feathers can teach us about how evolution works

A University of Arizona-led research team has shown that evolution is driven by species interaction within a community.











What the vibrant pigments of bird feathers can teach us about how evolution works
House finch colours itself with 24 carotenoid compounds derived from diverse dietary sources,
such as saguaro pollen [Credit: Alex Badyaev/tenbestphotos.com]

All living things exist within communities, where they depend on resources or services provided by other species. As community members change, so do the products the species depend on and share. The late George Gaylord Simpson, who was a professor of geosciences at the UA and one of the most influential evolutionary thinkers of the last century, proposed that these fluctuating dependencies should determine the speed of evolution.


The theory has been notoriously difficult to test because species interactions are both ubiquitous and ephemeral, said UA ecology and evolutionary biology professor Alexander Badyaev. But he and his team think they’ve found a way by examining evolution of biochemical pathways that produce colour diversity in birds.


Badyaev and his co-authors showed that the way biochemical processes are structured in birds holds the key to understanding how species gain and lose their reliance on others in their communities. Consequently, this dictates how quickly species can diversify and evolve.


The new study, which was published in Nature Communications earlier this month, both confirms this prediction and reveals the mechanisms that show how it works.


Badyaev studied the evolution of the pathways by which birds convert dietary carotenoids into molecules necessary for everything from vision to the immune system to feather pigmentation.


The team, which included undergraduate and graduate students, and a postdoctoral fellow in Badyaev’s lab, built and tested the structure of thousands of carotenoid biochemical pathways in nearly 300 bird species. Then, they explored how the pathways had changed over the last 50 million of years.











What the vibrant pigments of bird feathers can teach us about how evolution works
A combination of 16 different carotenoids make up striking colouration of male pyrrhuloxia
[Credit: Alex Badyaev/tenbestphotos.com]

«The importance of carotenoids for multiple functions contrasts with birds’ inability to create carotenoids themselves,» Badyaev said. «So a species deriving its dietary carotenoids from a single food source is hostage to the source’s disappearance.»


The solution resides in the structure of the biochemical pathways, where the same molecules might be interchangeably produced by different dietary carotenoids. Not only does this enable species to reliably receive their essential carotenoids despite environmental fluctuations, it also allows birds to explore additional biochemical pathways. Badyaev calls this «internalizing control.»


«Think about hanging by a rope off a cliff. With one rope, if it disappears, you die. If you have two and one fails, you get to live. But having a third safety rope allows enough stability that you can make something out of the first two — like a ladder — and thus take control of your trajectory while the stability lasts,» Badyaev said.


His team found that when species temporarily internalize control over their carotenoid production by capitalizing on multiple sources of carotenoids, they evolve at exceptionally high rates and produce some of the most extravagantly coloured birds in the world.


«But the moment you do this, you become susceptible to new external controls, and then the cycle repeats itself,» he said. «This is because both gains and losses of external controls occur with equal frequency.»


This research builds on both Darwin’s theory of evolution by natural selection and Simpson’s idea that an organism’s evolution is dependent on others in their community.


«It shows how adaptation and evolutionary change are linked mechanistically,» Badyaev said. «It shows why gaining and losing internal control is a key feature of evolution.»


Source: University of Arizona [April 24, 2019]



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