суббота, 12 октября 2019 г.

Researchers confirm timeline of human presence on Madagascar

A team of researchers has confirmed that humans arrived on Madagascar about 11,000 years ago, much earlier than commonly accepted estimates of 2,000 years.











Researchers confirm timeline of human presence on Madagascar
Kristina Douglass and her team systematically reviewed all of the archaeological radiocarbon dates for Madagascar
and confirmed the timeline of human presence on Madagascar [Credit: Roland Schmitt/SIPA]

Kristina Douglass, assistant professor of anthropology in the College of the Liberal Arts and a faculty member in the Institutes of Energy and the Environment, led the team of researchers who worked on this project. She said the debate over when people came to Madagascar has long been contentious.


For example, in 2018, two papers by different teams of researchers presented wildly different estimates of when people first arrived on the island, one estimating that Madagascar was settled 11,000 years ago, and the other arguing that people first arrived only 1,500 years ago.


To settle this debate, Douglass and her team collected all of the radiocarbon dates that have ever been generated for archaeological sites on the African island. Their work resulted in the most comprehensive database of radiocarbon dates for the island.


«The African continent has some of the oldest human remains on record, some of which are millions of years old,» Douglass said. «Yet, previous research suggested that this huge island that is not that far off the coast of Africa doesn’t get settled by people until about 2,000 years ago.»


To determine the timeline of human settlement, the researchers used statistical models to rank the dates using specific criteria, including whether the dated samples were clearly associated with human activities and whether the samples came from long or short-lived species, so that both the reliability and precision of radiocarbon dates could be evaluated. This method of «chronometric hygiene» had never been done for Madagascar.


«We looked at the type of material to see whether or not there was built in error based on the type of material,» Douglass said. «We took all of those criteria that we called ‘quality control’ for those dates, and we fed that into a system where we ranked the dates to know which dates are the most reliable based on our criteria and which are the least reliable.»


What Douglass and her team suggest in their paper is that the 11,000-year estimate of human presence is reliable.











Researchers confirm timeline of human presence on Madagascar
A map of sites in Madagascar used in the systematic review of archaeological radiocarbon dates
by Kristina Douglass and her team [Credit: Kristina Douglass]

Despite the reliability of this early arrival estimate, it is still unclear whether the evidence from 11,000 years ago is from permanent human settlements or if humans just visited the island temporarily, Douglass said.


«Somebody could have floated over to Madagascar by accident and left some remains,» she said.


The team’s paper also supports current evidence that cities started to emerge on Madagascar about 1,000 years ago.


Douglass said that confirming the timeline of human settlement is important for historical reasons, but it also has critical meaning for today’s changing world.


«The bigger context of why this matters is because this island with some of the world’s greatest biodiversity hotspots is going through significant environmental change, today and within the last 2,000 years,» Douglass said. «A huge number of animals went extinct on the island about 1,000 years ago—pygmy hippos, giant elephant birds, man-sized lemurs, giant tortoises.»


Douglass said it is important for understanding today’s environmental challenges to determine if these animals went extinct rapidly after a short co-existence with newly arrived people or if the extinctions were a more complex, longer-term process, involving climate change and human activity.


«If people arrived 1,500 years ago, then within 500 years, all of these animals go extinct and all of these changes happen,» Douglass said. «If people arrived 11,000 years ago, people have been coexisting with these environments for a much longer time, so the changes we see may be less abrupt or may have been caused by a significant shift in how people were using the landscape.»


Douglass added that human presence should not be used as the only indication of whether an environment is going to change. Human activity should be considered within a constellation of human-environment-climate dynamics.


«If people were there 11,000 years ago and practicing a certain kind of subsistence, that might be very different from 1,000 years ago when Madagascar is swept into booming Indian Ocean trade networks and people start building ports and cities,» Douglass said. «That is when we start to see the extinctions happen.»


The paper was published in Quaternary Science Reviews.


Author: Kevin Sliman | Source: Pennsylvania State University [October 08, 2019]



TANN



Archive


Genetics contributed to variations in stature among prehistoric Europeans

Genetics has largely contributed to changes in height that occurred among Europeans during the last 38,000 years, a new analysis has found.











Genetics contributed to variations in stature among prehistoric Europeans
Three ~31,000 years old skulls from Dolni Vestonice in the Czech Republic
[Credit: Martin Frouz & Jiri Svoboda]

Height has been variable over the course of human history, with the mean height of early anatomically modern male humans reaching about 175 centimeters (5 feet 8 inches) during the Paleolithic, though then declining to about 164 cm during the Mesolithic before rebounding slightly to about 167 cm during the Bronze Age. Today, the mean adult height of European men ranges between 170 and 180 cm. Bothe genetic and environmental factors — such as genetic drift, climate, and diet — are thought to have influenced these variations.


To tease apart the effects of genetics and environment, a University of Pennsylvania-led team applied a polygenic risk score for height to data from more than 1,000 ancient individuals from Western Europe. As they reported in the Proceedings of the National Academy of Sciences, they compared that genetically predicted height to heights deduced from bone samples.


«We show that changes over the past 35,000 [years] are largely predicted by genetics,» UPenn’s Iain Mathieson and colleagues wrote in their paper.


He and his colleagues developed a PRS for height based on GWAS summary statistics from the UK Biobank. They applied this score to published DNA data on 1,071 ancient individuals who lived in Western Eurasia between 38,000 and 1,100 years ago. At the same time, they generated stature estimates for 1,159 individuals who lived between 33,700 and 1,100 years ago based on skeletal data. The researchers noted, though, that while these samples came from similar temporal and geographic locations, there was limited overlap between those datasets, only 12 individuals.


Still, they found that PRS-based estimates of height and skeletal measurements both decreased, as expected, from the Early Upper Paleolithic, more than 25,000 years ago, to the Mesolithic periods and then increased between the Neolithic and post-Neolithic periods.


This initial decrease in height, the researchers noted, correlates with a time of population replacement and these new groups may have been shorter because of cold adaption or changes in resource availability. Meanwhile, the second change in height, an increase, correlates with the influx of Steppe ancestry into Central and Western Europe.


When they broke their PRS down into a score for sitting height and a score for standing height, the researchers noted that, as predicted by the genetic scores, sitting height changed less than standing height. But they also noted that the genetic score predicted a slight sitting height increase in the post-Neolithic era, which was not represented among their skeletal samples. This, they noted, could be due to the influence of environmental factors, opposing genetic effects, or their limited skeletal data.


They also uncovered shifts in height that correlated with geography, noting that even today Northern Europeans tend to be taller than Southern Europeans. In particular, they found that genetically predicted height did not increase with latitude in the Early Upper Paleolithic through Neolithic periods, but does in the post-Neolithic.


The researchers cautioned, though, that their analysis has a number of limitations. In particular, they relied on a PRS developed from a modern population whose underlying genetic population structure differs from these ancient populations, though they noted they tried to account for these differences.


«We must therefore be cautious in the interpretation of predicted genetic patterns where phenotypes cannot be directly measured, even if it is possible to control stratification,» they added. «Predicted genetic changes should be used as a baseline, against which non-genetic effects can be measured and tested.»


Source: Genome Web [October 08, 2019]



TANN



Archive


2019 excavations at the ancient Cypriot town of Pyla-Koutsopetria completed

The Department of Antiquities, Ministry of Transport, Communications and Works, has announced that the Pyla-Koutsopetria Archaeological Project (PKAP) completed its 15th season οn 14 June 2019 under the direction of Dr. Brandon R. Olson of Metropolitan State University of Denver, Dr Tom Landvatter of Reed College, and Dr R. Scott Moore of the Indiana University of Pennsylvania.











2019 excavations at the ancient Cypriot town of Pyla-Koutsopetria completed
View of the excavation site [Credit: Department of Antiquities,
Republic of Cyprus]

PKAP has excavated a series of small soundings at the site of Pyla-Vigla in the summers of 2008, 2009, 2012, and 2018. These excavations revealed the presence of a previously unknown early-Hellenistic fortification. Vigla is located on a steep plateau overlooking Larnaca Bay, which provided both a strong defensible location and an advantageous view of the coastal road between ancient Kition and Salamis.
The military nature of the site was demonstrated by the discovery of an extensive fortification system, projectile points, and lead sling bullets. The architectural, ceramic, and numismatic evidence discovered during previous seasons clearly date the occupation of the fortifications on Vigla to the late 4th and early 3rd centuries B.C., a period not well-documented in Cypriot history.


PKAP’s previous seasons’ results can be found in Pyla-Koutsopetria I: Archaeological Survey of an Ancient Coastal Town, published by the American Schools of Oriental Research in 2014, while the results of the 2018 season can be found in a recent article in the Journal of Hellenistic Pottery and Material Culture.











2019 excavations at the ancient Cypriot town of Pyla-Koutsopetria completed
View of the excavation site [Credit: Department of Antiquities,
Republic of Cyprus]

PKAP’s 2019 field season was focused on further understanding the site’s fortification system, as well as getting a clearer picture of the domestic/industrial areas within. Excavations around the north fortification wall revealed the continuation of an impressive in situ mudbrick wall first discovered in 2018.


The northern edge of the wall, was identified but its full extent remains elusive, and appears to be over 5m thick. Soundings placed on the south fortification wall, built on the slope, revealed a substantially well-preserved fieldstone wall with an important deposit of early Hellenistic ceramics found at the wall’s base.


Excavations in the centre of the plateau exposed several rooms with pottery sitting in situ on floors. Finds continued to show the military character of the site, including projectile points, iron weapons, and lead sling bullets. Future work planned for Vigla will focus more on the fortification’s interior architecture and the nature of activity within the residential/industrial areas.


Source: Department of Antiquities, Republic of Cyprus [October 08, 2019]



TANN



Archive


Study finds prehistoric humans ate bone marrow like canned soup 400,000 years ago

Tel Aviv University researchers, in collaboration with scholars from Spain, have uncovered evidence of the storage and delayed consumption of animal bone marrow at Qesem Cave near Tel Aviv, the site of many major discoveries from the late Lower Paleolithic period some 400,000 years ago.











Study finds prehistoric humans ate bone marrow like canned soup 400,000 years ago
Marrow inside a metapodial bone after six weeks of storage
[Credit: Dr. Ruth Blasco/AFTAU]

The research provides direct evidence that early Paleolithic people saved animal bones for up to nine weeks before feasting on them inside Qesem Cave.


The study, which was published in the Science Advances, was led by Dr. Ruth Blasco of TAU’s Department of Archaeology and Ancient Near Eastern Civilizations and Centro Nacional de Investigacion Sobre la Evolucion Humana (CENIEH) and her TAU colleagues Prof. Ran Barkai and Prof. Avi Gopher. It was conducted in collaboration with Profs. Jordi Rosell and Maite Arilla of Universitat Rovira i Virgili (URV) and Institut Catala de Paleoecologia Humana i Evolucio Social (IPHES); Prof. Antoni Margalida of University of Lleida, University of Bern, and the Institute for Game and Wildlife Research (IREC); and Prof. Daniel Villalba of University of Lleida.


«Bone marrow constitutes a significant source of nutrition and as such was long featured in the prehistoric diet,» explains Prof. Barkai. «Until now, evidence has pointed to immediate consumption of marrow following the procurement and removal of soft tissues. In our paper, we present evidence of storage and delayed consumption of bone marrow at Qesem Cave.»


«This is the earliest evidence of such behavior and offers insight into the socioeconomics of the humans who lived at Qesem,» adds Dr. Blasco. «It also marks a threshold for new modes of Paleolithic human adaptation.»


«Prehistoric humans brought to the cave selected body parts of the hunted animal carcasses,» explains Prof. Rosell. «The most common prey was fallow deer, and limbs and skulls were brought to the cave while the rest of the carcass was stripped of meat and fat at the hunting scene and left there. We found that the deer leg bones, specifically the metapodials, exhibited unique chopping marks on the shafts, which are not characteristic of the marks left from stripping fresh skin to fracture the bone and extract the marrow.»











Study finds prehistoric humans ate bone marrow like canned soup 400,000 years ago
Skinning in combination with tendon removal during the development of the experimental series.
Note the use of the tool with an inclination almost parallel to the bone
[Credit: Maite Arilla]

The researchers contend that the deer metapodials were kept at the cave covered in skin to facilitate the preservation of marrow for consumption in time of need.


The researchers evaluated the preservation of bone marrow using an experimental series on deer, controlling exposure time and environmental parameters, combined with chemical analyses. The combination of archaeological and experimental results allowed them to isolate the specific marks linked to dry skin removal and determine a low rate of marrow fat degradation of up to nine weeks of exposure.


«We discovered that preserving the bone along with the skin, for a period that could last for many weeks, enabled early humans to break the bone when necessary and eat the still nutritious bone marrow,» adds Dr. Blasco.


«The bones were used as ‘cans’ that preserved the bone marrow for a long period until it was time to take off the dry skin, shatter the bone and eat the marrow,» Prof. Barkai emphasizes.


Until recently, it was believed that the Paleolithic people were hunter gatherers who lived hand-to-mouth (the Stone Age version of farm-to-table), consuming whatever they caught that day and enduring long periods of hunger when food sources were scarce.











Study finds prehistoric humans ate bone marrow like canned soup 400,000 years ago
Examples of cut marks associated to disarticulation and/or skinning on deer metapodials from Amudian
and Yabrudian levels of Qesem Cave [Credit: Ruth Blasco]

«We show for the first time in our study that 420,000 to 200,000 years ago, prehistoric humans at Qesem Cave were sophisticated enough, intelligent enough and talented enough to know that it was possible to preserve particular bones of animals under specific conditions, and, when necessary, remove the skin, crack the bone and eat the bone marrow,» Prof. Gopher explains.


According to the research, this is the earliest evidence in the world of food preservation and delayed consumption of food. This discovery joins other evidence of innovative behaviors found in Qesem Cave including recycling, the regular use of fire, and cooking and roasting meat.


«We assume that all this was because elephants, previously a major source of food for humans, were no longer available, so the prehistoric humans in our region had to develop and invent new ways of living,» concludes Prof. Barkai. «This kind of behavior allowed humans to evolve and enter into a far more sophisticated kind of socioeconomic existence.»


Source: Tel Aviv University [October 09, 2019]



TANN



Archive


DNA study sheds new light on the people of the Neolithic battle axe culture

In an interdisciplinary study published in Proceedings of the Royal Society B, an international research team has combined archaeological, genetic and stable isotope data to understand the demographic processes associated with the iconic Battle Axe Culture and its introduction in Scandinavia.











DNA study sheds new light on the people of the Neolithic battle axe culture
This is a skeleton of a male individual associated with the Neolithic Age Battle Axe culture on exhibition
 in Linkoping, Sweden. Genomic DNA extracted from this individual was analyzed in the study
[Credit: Jonas Karlsson, Ostergotlands museum]

In 1953, a significant burial site belonging to the Battle Axe Culture was found when constructing a roundabout in Linkoping. 4,500 years ago, a man and a woman were buried together with a child, a dog and a rich set of grave goods including one of the eponymous battle axes. «Today, we call this site ‘Bergsgraven’. I have been curious about this particular burial for a long time. The collaboration of archaeologists with geneticists allows us to understand more about these people as individuals as well as where their ancestors came from,» says archaeogeneticist Helena Malmstrom of Uppsala University, lead author of the study.


The Scandinavian Battle Axe Culture appears in the archaeological record about 5,000 years ago and archaeologically it resembles the continental European Corded Ware Culture. «The appearance and development of the culture complex has been debated for a long time, especially whether it was a regional phenomenon or whether it was associated with migratory processes of human groups, and — if the latter — from where,» says osteoarchaeologist Jan Stora of Stockholm University, one of the senior authors of the study.


By sequencing the genomes of prehistoric individuals from present-day Sweden, Estonia and Poland, the research team showed that the Scandinavian Battle Axe Culture and continental Corded Ware Culture share a common genetic ancestry, which had not been present in Scandinavia or central Europe before 5,000 years ago. «This suggests that the introduction of this new cultural manifestation was associated with movements of people. These groups have a history which we ultimately can trace back to the Pontic Steppe north of the Black Sea,» says population geneticist Torsten Gunther of Uppsala University, co-lead author of the study.


In previous studies, the research team had been able to show that other cultural changes during the Stone Age, such as the introduction of farming practices, were also associated with movements of people. Torsten Gunther: «Again, archaeogenomic analyses reveal new and surprising results concerning demographic processes in the Stone Age.» Jan Stora adds: «Prehistoric movements of people have played a major role in spreading innovations. But there is also some integration and reconnection of previous elements. For example, we find that people sharing the genetic signal of the Battle Axe sites were re-using megalithic tombs for their burials.»


Comparisons between these individuals and other prehistoric Scandinavians provided further valuable insights. Mattias Jakobsson, population geneticist at Uppsala University and one of the senior authors of this study, notes: «It is also interesting that the herders from the Battle Axe Culture differed from other contemporary farmer and hunter-gatherer groups in Scandinavia. At least three genetically and culturally different groups lived side-by-side for centuries and did not mix a lot.»


There is some evidence for low levels of genetic admixture between the incoming herders and other farming cultures. The research team was not able to determine whether this took place before or after their arrival in Scandinavia. «That remains an open question and still leaves room for future studies as more data from additional individuals as well as other geographic regions should provide a more detailed resolution,» concludes Helena Malmstrom.


The Bergsgraven burial as well as a reconstruction of the individuals is usually on exhibition at Ostergotlands Museum in Linkoping. «Ostergotlands Museum is currently closed for renovation and renewal. Therefore, the display of the Bergsgraven grave has been temporarily removed, but it will be a central part of the upcoming exhibition, in which we aim to integrate current archaeological and historical research. This is a rare opportunity to build a new exhibition, and of course we want to tell the audience about the new analyses and interpretations made of the material,» says Per Nilsson, archaeologist at Ostergotlands Museum.


Source: Uppsala University [October 09, 2019]



TANN



Archive


Cretan tomb’s location may have strengthened territorial claim

Examining the position occupied by tombs in their landscape in Prepalatial Crete gives us new insights into the role played by burial sites, mortuary practices and the deceased in the living society.

Tholos A at Apesokari, in south-central Crete (Greece) is one of ca. 85 Early and Middle Bronze Age circular tombs discovered so far in Crete. A recently published article contributes to the understanding of Tholos A in its landscape and chronological context, while offering an opportunity to address questions pertaining to community, communal identity, strategies of exploitation of the local landscape, and regional interactions in Prepalatial Crete.
The article by Dr. Sylviane Dederix of the University of Heidelberg in Germany has been published in De Gruyter’s open access journal, Open Archaeology.


Tholos A was excavated during World War II by August Schorgendorfer, an Austrian archaeologist and officer in the Wehrmacht, but it remained unstudied until a few years ago, when a new research program was started by Dr. Georgia Flouda of the Heraklion Archaeological Museum. As part of this program, Geographical Information Systems (GIS) were employed by Dr. Dederix to examine the possibility that concerns of visibility, intervisibility and invisibility may have influenced the placement of Tholos A in the landscape of Bronze Age Apesokari.











Cretan tomb's location may have strengthened territorial claim
Plan of the Tholos A at Apesokari [Credit: SchorGendorFer 1951a,
via Georgia Flouda]

Built on a sloping ledge of bedrock overlooking the Mesara Plain, Tholos A at Apesokari occupies an unusual (and quite inconvenient) topographic setting in comparison with most circular tombs. The article discusses GIS-based viewshed analyses that were undertaken to assess whether such a location was intended to maximize the visual impact of the tomb and ensure (or, conversely, prevent) intervisibility with specific features in the landscape. The results of the analyses demonstrate that, even though Tholos A was highly visible in its local landscape, it was invisible from the habitation site and a second circular tomb known in the surroundings. The choice of location of Tholos A may, however, have been intended to visually control parcels of land located in the valley below and/or to increase the visibility of the tomb from an optimal path traversing the area.


«At the cutting edge of the developing collaboration between GIS analysis and prehistoric fieldwork, Dederix addresses a specific question about the siting of one Minoan tomb to investigate how digital technology can work in the service of archaeology rather than the other way round,» said Lucy Goodison, the Phyllis and Eileen Gibbs Travelling Fellow at Newnham College Cambridge.


Source: De Gruyter [October 09, 2019]



TANN



Archive


Mouse Nous The brain is home to millions of neurons – their…


Mouse Nous


The brain is home to millions of neurons – their different tree-like structures branch across brain areas in a diverse ‘forest’ of connections, helping to process information, coordinate our actions and form memories. Using viruses to light up individual mouse neurons, The MouseLight Project is building a 3D model of the brain, piecing together microscopy images of glowing cells using algorithms to map out their tracks. Recently passing the 1000-neuron mark, the project reveals some brain areas have groups of similar neurons, while other regions are peppered with a mixture. With the goal of understanding this complex organisation, the database continues to grow – here thousands of neurons blink into place in a 3D reconstruction, adding to the totalled length of 87+ metres of neurons mapped inside a brain the size of light bulb.


Written by John Ankers



You can also follow BPoD on Instagram, Twitter and Facebook


Archive link


Swinside or Sunkenkirk Neolithic Stone Circle, Broughton in Furness, Lake District,...











Swinside or Sunkenkirk Neolithic Stone Circle, Broughton in Furness, Lake District, 12.10.19.


Source link


Calcite | #Geology #GeologyPage #Minerals Locality: the West…


Calcite | #Geology #GeologyPage #Minerals


Locality: the West Cumbria iron mining district in north west England.


Dimensions: 9.5 × 7.8 × 4.2 cm


Photo Copyright © Crystal Classics


Geology Page

www.geologypage.com — view on Instagram https://scontent.cdninstagram.com/vp/2dcbc45c19d99952e2053647294097f5/5E1F1EA7/t51.2885-15/sh0.08/e35/s640x640/72617978_2378900052222561_8023361363520336175_n.jpg?_nc_ht=scontent.cdninstagram.com


Swinside or Sunkenkirk Neolithic Stone Circle in Autumn, Lake District, 12.10.19.


Swinside or Sunkenkirk Neolithic Stone Circle in Autumn, Lake District, 12.10.19.


Source link


Prehistoric Rock Art, Kelvingrove Museum, Glasgow, 29.9.19.


Prehistoric Rock Art, Kelvingrove Museum, Glasgow, 29.9.19.


Source link


Prehistoric Jet Necklace (2500 to 1500 BCE) from Monybachach, Argyll, Kelvingrove Museum,...


Prehistoric Jet Necklace (2500 to 1500 BCE) from Monybachach, Argyll, Kelvingrove Museum, Glasgow, 29.9.19.


Source link


2019 October 12 Interplanetary Earth Cassini Imaging Team, SSI,…


2019 October 12


Interplanetary Earth
Cassini Imaging Team, SSI, JPL, ESA, NASA & NASA/JHU Applied Physics Lab/Carnegie Inst. Washington


Explanation: In an interplanetary first, on July 19, 2013 Earth was photographed on the same day from two other worlds of the Solar System, innermost planet Mercury and ringed gas giant Saturn. Pictured on the left, Earth is the pale blue dot just below the rings of Saturn, as captured by the robotic Cassini spacecraft then orbiting the outermost gas giant. On that same day people across planet Earth snapped many of their own of their own pictures of Saturn. On the right, the Earth-Moon system is seen against the dark background of space as captured by the robotic MESSENGER spacecraft, then in Mercury orbit. MESSENGER took its image as part of a search for small natural satellites of Mercury, moons that would be expected to be quite dim. In the MESSENGER image, the Earth (left) and Moon (right) are overexposed and shine brightly with reflected sunlight. Destined not to return to their home world, both Cassini and Messenger have since retired from their missions of Solar System exploration.


∞ Source: apod.nasa.gov/apod/ap191012.html


Saturn Surpasses Jupiter After Discovery of 20 New Moons


Figure 1: The discovery images for the newly found very distant prograde moon of Saturn. They were taken on the Subaru Telescope with about one hour between each image. The background stars and galaxies do not move, while the newly discovered Saturnian moon, highlighted with an orange bar, shows motion between the two images. (Photographs are courtesy of Scott Sheppard.)


Using the Subaru Telescope, a team led by Carnegie’s Scott S. Sheppard has found 20 new moons orbiting Saturn. This brings the ringed planet’s total number of moons to 82, surpassing Jupiter, which has 79. The discovery was announced on October 7, 2019, by the International Astronomical Union’s Minor Planet Center.


Each of the newly discovered moons is about five kilometers, or three miles, in diameter. Seventeen of them orbit the planet backwards, or in a retrograde direction, meaning their movement is opposite of the planet’s rotation around its axis. The other three moons orbit in the prograde—the same direction as Saturn rotates.


Two of the prograde moons are closer to the planet and take about two years to travel once around Saturn. The more-distant retrograde moons and one of the prograde moons each take more than three years to complete an orbit.


«Studying the orbits of these moons can reveal their origins, as well as information about the conditions surrounding Saturn at the time of its formation,» Sheppard explained.


The outer moons of Saturn appear to be grouped into three different clusters in terms of the inclinations of the angles at which they are orbiting around the planet. Two of the newly discovered prograde moons fit into a group of outer moons with inclinations of about 46 degrees called the Inuit group, as they are named after Inuit mythology. These moons may have once comprised a larger moon that was broken apart in the distant past. Likewise, the newly announced retrograde moons have similar inclinations to other previously known retrograde Saturnian moons, indicating that they are also likely fragments from a once-larger parent moon that was broken apart. These retrograde moons are in the Norse group, with names coming from Norse mythology. One of the newly discovered retrograde moons is the farthest known moon around Saturn.


«This kind of grouping of outer moons is also seen around Jupiter, indicating violent collisions occurred between moons in the Saturnian system or with outside objects such as passing asteroids or comets,» explained Sheppard.


The other newly found prograde moon has an inclination near 36 degrees, which is similar to the other known grouping of inner prograde moons around Saturn called the Gallic group. But this new moon orbits much farther away from Saturn than any of the other prograde moons, indicating it might have been pulled outwards over time or might not be associated with the more inner grouping of prograde moons.


If a significant amount of gas or dust were present when a larger moon broke apart and created these clusters of smaller moon fragments, there would have been strong frictional interactions between the smaller moons and the gas and dust, causing them to spiral into the planet.


«In the Solar System’s youth, the Sun was surrounded by a rotating disk of gas and dust from which the planets were born. It is believed that a similar gas-and-dust disk surrounded Saturn during its formation,» Sheppard said. «The fact that these newly discovered moons were able to continue orbiting Saturn after their parent moons broke apart indicates that these collisions occurred after the planet-formation process was mostly complete and the disks were no longer a factor.»



Figure 2: An artist’s conception of the 20 newly discovered moons orbiting Saturn. These discoveries bring the planet’s total moon count to 82, surpassing Jupiter for the most in our Solar System. Studying these moons can reveal information about their formation and about the conditions around Saturn at the time. Illustration is courtesy of the Carnegie Institution for Science. (Illustration is courtesy of the Carnegie Institution for Science. Saturn image is courtesy of NASA/JPL-Caltech/Space Science Institute. Starry background courtesy of Paolo Sartorio/Shutterstock.)


The new moons were discovered using the Subaru Telescope. The observing team included Sheppard, David Jewitt of UCLA, and Jan Kleyna of the University of Hawaii.


«Using some of the largest telescopes in the world, we are now completing the inventory of small moons around the giant planets,» says Scott Sheppard. «They play a crucial role in helping us determine how our Solar System’s planets formed and evolved.»

Last year, Sheppard discovered 12 new moons orbiting Jupiter and Carnegie hosted an online contest to name five of them.


«I was so thrilled with the amount of public engagement over the Jupiter moon-naming contest that we’ve decided to do another one to name these newly discovered Saturnian moons,» Sheppard said. «This time, the moons must be named after giants from Norse, Gallic, or Inuit mythology.» Contest details are available here.



Archive link


Celebrating a Mission That Changed How We Use Radar


NASA — STS-59 Mission patch.


October 11, 2019


Oct. 11, 2019, marks the 25th anniversary of the end of a space mission that transformed the way we use radar to observe large-scale environmental processes on our home planet. The Spaceborne Imaging Radar-C and X-Band Synthetic Aperture Radar (SIR-C/X-SAR) mission made available to people worldwide the scientific data used to this day to inform decisions to slow and mitigate climate change.


The SIR-C instrument, built by NASA’S Jet Propulsion Laborator in Pasadena, California, and the X-SAR instrument, built by the German Aerospace Center (DLR), constituted the most advanced imaging radar system ever used in air or space. During hundreds of orbits on two flights aboard the Space Shuttle Endeavour, in April and October 1994, the radar system made multiple passes over 19 «supersites» — areas of scientific interest in such locations as the Sahara, Brazil, the Alps and the Gulf Stream. It also imaged events occurring during the flights, such as as a volcano erupting in Russia.



Image above: With SIR-C/X-SAR instruments mounted in the cargo bay atop the shuttle, the Endeavour crew flew upside down, using precise navigation, the hinge on the X-band antenna and «electronic steering» in the C- and L-band antennas to point the radars at «supersites» of scientific interest on Earth. Image Credits: NASA/JPL-Caltech.


«The many innovationsof SIR-C/X-SAR have been used in virtually every air- and spaceborne radar mission since, starting with NASA’s Shuttle Radar Topography Mission, which mapped 80% of the Earth in 2000,» said Tony Freeman, now manager of JPL’s Innovation Foundry, who led end-to-end calibration of SIR-C. «DLR’s TerraSAR-X and TanDEM-X missions have since filled remaining gaps.»


Radar imaging of Earth has never been the same since SIR-C/X-SAR’s demonstration of what’s known as simultaneous multifrequency, fully polarized, repeat-pass interferometric SAR. To unpack that sizable trunk of terminology, let’s start with «synthetic aperture radar»: Since the late 1970s, NASA has been imaging Earth with radar — in darkness, under cloud cover or vegetation, even underground — using the movements of a host airplane or spacecraft to «synthesize» an «aperture» much larger than the antenna itself. The larger the aperture, the greater the image resolution. Indeed, SIR-C’s predecessors, SIR-A and SIR-B, were synthetic aperture radar missions.


However, unlike SIR-C/X-SAR, neither predecessor made radar observations simultaneously in three frequencies — C-, L- and X-band — using three adjacent antennas combined into a massive, 12-by-4-meter, 11.5-ton structure. That advance, analogous to the leap from black-and-white to color film, allowed the mission to collect data in different scales, providing a crisp snapshot of each targeted feature, unmuddied by possible changes over time.


Blazing a Trail


In addition to multiple frequencies, some observations were made in multiple «polarizations.» Radio frequency waves can be either horizontal (in a wavy plane parallel to the ground) or vertical (in a plane perpendicular to the ground). The C- and L-band antennas could send and receive waves of both horizontal and vertical polarization. Using this «fully polarized» data, scientists can separate out the scattering of radar waves to distinguish, for example, vegetated from unvegetated terrain.


SIR-C/X-SAR wanted to capture changes over time; that’s why it flew on shuttle flights six months apart. To observe the same supersites during both flights and to make consistent daily passes over them, the shuttle crew used sophisticated algorithms to navigate the spacecraft in precise orbits as close as 10 meters apart. And they did this flying upside down, since the cargo bay holding the instruments was on top of the shuttle. While the X-band antenna had a hinge, the C- and L-band antennas were fixed at a particular angle, but they had «electronic steering» that allowed them to «see» to either side of what was right in front of them.


Those repeated, slightly offset passes over the same terrain were essential for the data-processing technique of interferometry. Combining views, interferometry creates detailed, 3D topographical images of a target at the moment of simultaneous observations. And it can reveal even minute changes in the target between successive observations — like the gradual creep of an earthquake fault or the movement of an ice sheet.



Image above: These ancient river channels, invisible to the human eye beneath the deep, dry sand of the Sahara Desert, were revealed for the first time by SIR-C/X-SAR instruments during their second shuttle flight in October 1994. Image Credits: NASA/JPL-Caltech.


The SIR-C/X-SAR dataset proved immediately useful, revealing, for instance, ancient riverbeds beneath the Sahara — an artifact of preindustrial climate change — and remains in high demand.


«SIR-C/X-SAR was the path opener for multiple U.S. and international missions that followed,» said Charles Elachi, the mission’s principal investigator before he became director of JPL. «Imaging of subsurface river channels in the Eastern Sahara enabled new understanding of the environmental history of that and other arid regions. Using multiple frequencies enabled for the first time ‘color’ radar images that have been used extensively to map vegetation and forests and extract their vegetation content. Using repeat-pass interferometry enabled us for the first time to map surface motion at the centimeter level. This technique is now commonly used to map motions resulting from earthquakes, volcanic eruptions and other natural disasters.»


Freeman agrees: «SIR-C/X-SAR was innovative on so many fronts: We knew what we were working on was something special, but we didn’t know at the time how many firsts the mission would rack up».


The NASA Image and Video Library makes mission data available to researchers worldwide. The University of Michigan hosts a search tool for accessing its own vast SIR-C/X-SAR database. And in its MapReady tool the University of Alaska Satellite Facility has processed the data for compatibility with multiple computer platforms.


Missions using technologies pioneered by SIR-C/X-SAR have revealed changes in Earth’s natural features over increasingly meaningful periods, informing long-term policy to prevent and mitigate climate change. At the same time, they reveal the immediate effects of natural disasters rapidly enough to advise first responders.



Image above: Using the technique of interferometric SAR first demonstrated on SIR-C/X-SAR, four international space agencies cooperated to combine many years’ worth of radar observations over the Greenland ice sheet to map its depth and accelerating speed of loss. Image Credits: Courtesy of NASA/GSFC/Jefferson Beck.


SIR-C/X-SAR was a collaboration of NASA, DLR and the Italian Space Agency (ASI), which contributed to the ground segment for X-SAR observations. JPL managed the mission for NASA. DLR was responsible for calibration, operations and data processing for X-SAR.


Related links:


NASA Image and Video Library: https://images.nasa.gov/


MapReady: https://www.asf.alaska.edu/data-tools/mapready/


Images (mentioned), Text, Credits: NASA/JPL/Matthew Segal.


Greetings, Orbiter.chArchive link


Space Station Science Highlights: Week of October 7, 2019


ISS — Expedition 61 Mission patch.


Oct. 11, 2019


While it was a week full of spacewalks, the crew aboard the International Space Station fit in some science during the week of Oct. 7. In addition to prepping for a series of battery Extravehicular Activities (EVAs), research conducted included collecting air quality samples, watering veggies and recharging free-flying robot assistants. Research like this conducted aboard the space station is a crucial stepping stone for Artemis, NASA’s plans to go forward to the Moon and on to Mars.



Image above: NASA astronaut Andrew Morgan takes an out-of-this-world «space-selfie» during a spacewalk to upgrade space station power systems on the Port-6 (P6) truss structure. He and fellow NASA astronaut Christina Koch (out of frame) worked for about seven hours to begin the latest round of upgrading the station’s large nickel-hydrogen batteries with newer, more powerful lithium-ion batteries. Image Credit: NASA.


Here are details on some of the science conducted on the orbiting laboratory during the week:


Checking out the air


This past week, the crew helped collect samples for the Spacecraft Atmosphere Monitor (S.A.M.). One of the most important conditions associated with crew health during spaceflight is air quality. Currently, atmosphere quality aboard the space station is assessed by periodic sampling and ground-based analysis using sophisticated instruments. Since samples cannot be returned to Earth during future exploration missions, a complement of smaller and more reliable instruments such as S.A.M. becomes essential to monitor the crew environment.


It’s planting season



Image above: NASA astronaut Christina Koch checks progress on small plant pillows for the Veg-04B investigation. Veg-04B focuses on the effects of light quality and fertilizer on the leafy Mizuna mustard green crop, microbial food safety, nutritional value and the taste acceptability by the crew. Image Credit: NASA.


Watering crops on the space station is a bit different than on Earth. Rather than pouring water onto soil, the crew injected water to small plant pillows that provide needed water to the growing veggies. This is part of Veg-04B, one piece of a phased research project attempting to address the need for a continuous fresh-food production system in space to supplement typical pre-packaged foods for astronauts. Veg-04B focuses on the effects of light quality and fertilizer on the leafy Mizuna mustard green crop, microbial food safety, nutritional value and the taste acceptability by the crew.



Image above: NASA astronaut Andrew Morgan reviews procedures the day before the EVA that took place on Oct. 6 to upgrade the space station’s batteries. Image Credit: NASA.


Getting charged up


The free-flying robot facility known as Astrobee got its batteries charged up this week. The facility is designed to help scientists and engineers develop and test technologies that can assist astronauts with routine chores and give ground controllers additional eyes and ears on the space station. The autonomous robots, powered by fans and vision-based navigation, perform crew monitoring and sampling and logistics management. The robots accommodate up to three investigations.



Animation above: NASA astronaut Christina Koch spins a Grab Sample Container, a device that is used for collecting environmental samples for the Spacecraft Atmosphere Monitor.
Image Credit: NASA.


Other investigations on which the crew performed work:


— The brain is capable of self-regulating blood flow even when the heart and blood vessels cannot maintain an ideal blood pressure. The Cerebral Autoregulation investigation tests whether this self-regulation improves in the microgravity environment of space.
https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=1938


— The Food Physiology experiment is designed to characterize the key effects of an enhanced spaceflight diet on immune function, the gut microbiome and nutritional status indicators.
https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7870


— Actiwatch is a nonintrusive, wearable monitor that analyzes a crew member’s circadian rhythms, sleep-wake patterns and activity.
https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Facility.html?#id=838


— ISS Ham Radio provides students, teachers, parents and other members of the community an opportunity to communicate directly with astronauts using Ham radio units.
https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=337


— Food Acceptability examines changes in the appeal of food aboard the space station during long-duration missions. “Menu fatigue” from repeatedly consuming a limited choice of foods may contribute to the loss of body mass often experienced by crew members, potentially affecting astronaut health, especially as mission length increases.
https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7562


— The Microgravity Crystals investigation crystallizes a membrane protein that is integral to tumor growth and cancer survival. Results may support development of cancer treatments that target the protein more effectively and with fewer side effects.
https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7977


— BEST studies the use of DNA sequencing to identify unknown microbial organisms and improve understanding of how humans, plants and microbes adapt to living in space.
https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7687


Related links:


Expedition 61: https://www.nasa.gov/mission_pages/station/expeditions/expedition61/index.html


Artemis: https://www.nasa.gov/artemis


Spacecraft Atmosphere Monitor (S.A.M.): https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=1843


Veg-04B: http://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7895


Astrobee: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Facility.html?#id=1891


ISS National Lab: https://www.issnationallab.org/


Spot the Station: https://spotthestation.nasa.gov/


Space Station Research and Technology: https://www.nasa.gov/mission_pages/station/research/index.html


International Space Station (ISS): https://www.nasa.gov/mission_pages/station/main/index.html


Images (mentioned), Animation (mentioned), Text, Credits: NASA/Michael Johnson/John Love, Lead Increment Scientist Expedition 61.


Best regards, Orbiter.chArchive link


Second of Five Power Upgrade Spacewalks Wraps Up



ISS — Expedition 61 Mission patch / EVA — Extra Vehicular Activities patch.


October 11, 2019


Expedition 61 Flight Engineers Christina Koch and Andrew Morgan of NASA concluded their spacewalk at the International Space Station at 2:23 p.m. EDT. During six-hour and 45-minute spacewalk, the two NASA astronauts continued the replacement of nickel-hydrogen batteries with newer, more powerful lithium-ion batteries on the far end of the station’s port truss.


Astronauts also were able to accomplish several get-ahead tasks setting up for the next spacewalk.



Image above: Astronauts Andrew Morgan and Christina Koch are pictured in their U.S. spacesuits during a spacewalk earlier this year. Image above:


These new batteries provide an improved power capacity for operations with a lighter mass and a smaller volume than the nickel-hydrogen batteries. On Oct. 16, Morgan and NASA astronaut Jessica Meir are scheduled to venture outside for another spacewalk to continue the battery replacements on the first of the two power channels for the station’s far port truss. The following spacewalks dedicated to the battery upgrades are scheduled on Oct. 21 and 25.



October 11, 2019 spacewalk. Image Credit: NASA TV

After completion of the battery spacewalks, the second half of this sequence of spacewalks will focus on repairs to the space station’s Alpha Magnetic Spectrometer. Dates for those spacewalks still are being discussed, but they are expected to begin in November.


Space station crew members have conducted 220 spacewalks in support of assembly and maintenance of the orbiting laboratory. Spacewalkers have now spent a total of 57 days 13 hours and 12 minutes working outside the station.


Related links:


Expedition 61: https://www.nasa.gov/mission_pages/station/expeditions/expedition61/index.html


Alpha Magnetic Spectrometer (AMS): https://www.nasa.gov/feature/extending-science-in-the-search-for-the-origin-of-the-cosmos


Space Station Research and Technology: https://www.nasa.gov/mission_pages/station/research/index.html


International Space Station (ISS): https://www.nasa.gov/mission_pages/station/main/index.html


Images (mentioned), Text, Credits: NASA/Norah Moran.


Best regards, Orbiter.chArchive link


Meteor Activity Outlook for October 12-18, 2019

David Young captured this bright meteor on the morning of October 3, 2019, from Fremont, California USA. ©David Young

During this period the moon reaches its full phase on Sunday October 13th. At this time the moon will be located opposite the sun and lie above the horizon all night long. Toward the end of this period there will be a moonless period of a couple of hours between dusk and moonrise. Unfortunately meteor rates at this time are very low. The estimated total hourly meteor rates for evening observers this week is near 3 for those viewing from the northern hemisphere and 2 for those located south of the equator. For morning observers the estimated total hourly rates should be near 12 as seen from mid-northern latitudes (45N) and 7 as seen from tropical southern locations (25S) . The actual rates will also depend on factors such as personal light and motion perception, local weather conditions, alertness and experience in watching meteor activity. Rates are reduced during this period due to moonlight. Note that the hourly rates listed below are estimates as viewed from dark sky sites away from urban light sources. Observers viewing from urban areas will see less activity as only the brightest meteors will be visible from such locations.


The radiant (the area of the sky where meteors appear to shoot from) positions and rates listed below are exact for Saturday night/Sunday morning October 12/13. These positions do not change greatly day to day so the listed coordinates may be used during this entire period. Most star atlases (available at science stores and planetariums) will provide maps with grid lines of the celestial coordinates so that you may find out exactly where these positions are located in the sky. A planisphere or computer planetarium program is also useful in showing the sky at any time of night on any date of the year. Activity from each radiant is best seen when it is positioned highest in the sky, either due north or south along the meridian, depending on your latitude. It must be remembered that meteor activity is rarely seen at the radiant position. Rather they shoot outwards from the radiant so it is best to center your field of view so that the radiant lies at the edge and not the center. Viewing there will allow you to easily trace the path of each meteor back to the radiant (if it is a shower member) or in another direction if it is a sporadic. Meteor activity is not seen from radiants that are located below the horizon. The positions below are listed in a west to east manner in order of right ascension (celestial longitude). The positions listed first are located further west therefore are accessible earlier in the night while those listed further down the list rise later in the night.





Radiant Positions at 21:00 LDST


Radiant Positions at 21:00 Local Daylight Saving Time






Radiant Positions at 01:00 LDST


Radiant Positions at 1:00 Local Daylight Saving Time






Radiant Positions at 05:00 LDST


Radiant Positions at 5:00 Local Daylight Saving Time





These sources of meteoric activity are expected to be active this week.


.


Detailed descriptions of each source will continue next week when viewing conditions improve.






















































































SHOWER DATE OF MAXIMUM ACTIVITY CELESTIAL POSITION ENTRY VELOCITY CULMINATION HOURLY RATE CLASS
RA (RA in Deg.) DEC Km/Sec Local Daylight Saving Time North-South
Northern Taurids (NTA) Nov 03 01:54 (028) +16 28 02:00 1 – <1 II
Southern Taurids (STA) Oct 10 02:08 (032) +09 27 02:00 2 – 2 II
Orionids (ORI) Oct 22 05:46 (087) +16 67 05:00 3 – 2 I
epsilon Geminids (EGE) Oct 11 06:24 (096) +28 70 06:00 1 – <1 II
nu Eridanids (NUE) Sep 24 06:20 (095) +10 67 06:00 <1 – <1 IV
October Ursa Majorids (OCU) Oct 15 09:40 (145) +65 56 09:00 <1 – <1 IV
Leonis Minorids (LMI) Oct 23 10:02 (151) +40 62 10:00 <1 – <1 II

Source link


2019 September 26 Da Vinci Rise Image Credit & Copyright:…


2019 September 26


Da Vinci Rise
Image Credit & Copyright: Likai Lin


Explanation: An old Moon rose this morning, its waning sunlit crescent shining just above the eastern horizon before sunrise. But earthshine, light reflected from a bright planet Earth, lit the shadowed portion of the lunar disk and revealed most of a familiar lunar near side to early morning risers. In fact, a description of earthshine in terms of sunlight reflected by Earth’s oceans illuminating the Moon’s dark surface was written over 500 years ago by Leonardo da Vinci. One lunation ago this old Moon also rose above the eastern horizon. Its sunlit crescent and da Vinci glow were captured in stacked exposures from the Badain Jilin Desert of Inner Mongolia, China on August 29, 2019. This year marks the 500th anniversary of Leondardo da Vinci’s death.


∞ Source: apod.nasa.gov/apod/ap190926.html


Featured

    Солнечное затмение 14 декабря 2020 года  — полное  солнечное затмение  142  сароса , которое лучше всего будет видно в юго-восточной час...

Popular