вторник, 16 апреля 2019 г.

Variations in the ‘fogginess’ of the universe identify a milestone in cosmic history

 

New study suggests that reionisation occurred 1.1 billion years after the big bang 
Credit: Kavli Institute for Cosmology
Hi-res image

Large differences in the ‘fogginess’ of the early universe were caused by islands of cold gas left behind when the universe heated up after the big bang, according to an international team of astronomers.


The results, reported in the Monthly Notices of the Royal Astronomical Society, have enabled astronomers to zero in on the time when reionisation ended and the universe emerged from a cold and dark state to become what it is today: full of hot and ionised hydrogen gas permeating the space between luminous galaxies.


Hydrogen gas dims light from distant galaxies much like streetlights are dimmed by fog on a winter morning. By observing this dimming in the spectra of a special type of bright galaxies, called quasars, astronomers can study conditions in the early universe.


“We expected the light from quasars to vary from place to place at most by factor of two at this time, but it is seen to vary by factor of about 500,” said lead author Girish Kulkarni, who completed the research while a postdoctoral researcher at the Kavli Institute, University of Cambridge. “Some hypotheses were put forward for why this is so, but none were satisfactory.”


The new study concludes that these variations result from large regions full of cold hydrogen gas present in the universe when it was just one billion years old, a result which enables researchers to pinpoint when reionisation ended.


During reionisation, when the universe transitioned out of the cosmic ‘dark ages’, the space between galaxies was filled with a plasma of ionised hydrogen with a temperature of about 10,000˚C. This is puzzling because fifty million years after the big bang, the universe was cold and dark. It contained gas with temperature only a few degrees above absolute zero, and no luminous stars and galaxies. How is it then that today, about 13.6 billion years later, the universe is bathed in light from stars in a variety of galaxies, and the gas is a thousand times hotter?


Answering this question has been an important goal of cosmological research over the last two decades. The conclusions of the new study suggests that reionisation occurred 1.1 billion years after the big bang (or 12.7 billion years ago), quite a bit later than previously thought.


The team of researchers from India, the UK, Canada, Germany, and France drew their conclusions with the help of state-of-the-art computer simulations performed on supercomputers based at the Universities of Cambridge, Durham, and Paris, funded by the UK Science and Technology Facilities Council (STFC) and the Partnership for Advanced Computing in Europe (PRACE).


“When the universe was 1.1 billion years old there were still large pockets of the cosmos where the gas between galaxies was still cold and it is these neutral islands of cold gas that explain the puzzling observations,” said Martin Haehnelt of the Kavli Institute, University of Cambridge, who led the group that conducted this research, supported by funding from the European Research Council (ERC).


“This finally allows us to pinpoint the end of reionisation much more accurately than before,” said Laura Keating of the Canadian Institute of Theoretical Astrophysics.


The new study suggests that the universe was reionised by light from young stars in the first galaxies to form.


“Late reionisation is also good news for future experiments that aim to detect the neutral hydrogen from the early universe,” said Kulkarni, who is now based at the Tata Institute of Fundamental Research in India. “The later the reionisation, the easier it will be for these experiments to succeed.”

Reference:

Girish Kulkarni et al. ‘Large Ly α opacity fluctuations and low CMB τ in models of late reionisation with large islands of neutral hydrogen extending to z < 5:5.’ Monthly Notices of the Royal  Astronomical Society (2019). DOI: 10.1093/mnrasl/slz025

Adapted from a press release by Girish Kulkarni (Tata Institute of Fundamental Research)





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Iron Age burials discovered in central Thailand

Pink canopy tents were erected over two opened pits in a small sugar-apple plantation not far from the Central Mosque, or Masjid Ban Suan, in Muang district of Lop Buri. At first glance, it looked like nobody was here. Then someone emerged from the site. He had a broken piece of clay pot in his hand.











Iron Age burials discovered in central Thailand
Sorathach Rotchanarat excavating the second pit [Credit: Karnjana Karnijanatawe]

Sorathach Rotchanarat, an archaeologist from the Fine Arts Department, spent a couple months with his team to dig out the soil and collect evidence to indicate that there was a community living in the area since the New Iron Age, around 3,100-3,800 years ago. The site he most recently discovered is called Khok Phutsa, the newest archaeological site out of 116 that have been excavated in the Lop Buri River Basin over the past 80 years. Khok Phutsa is located about 5km from the King Narai the Great’s Monument, the landmark of the city.


«I was very excited and happy when we first discovered some artefacts last December. So far we’ve found more than 10,000 broken clay pots and other items at this site,» he said.











Iron Age burials discovered in central Thailand
The human skeleton in the first pit and potholes indicating the use of land after
the new Iron Age [Credit: Karnjana Karnijanatawe]

The excavation of Khok Phutsa started in December last year, after the land owner informed the Fine Arts Department about the discovery of ancient clay pot fragments. Alongside Sorathach, a team of archaeologists led by Pakpadee Yukongdi of the Fine Arts Department, together with Dr Roberto Ciarla and Dr Fiorella Rispoli from Italy, visited the site. The Italian experts worked with the Fine Arts Department through the joint Thai-Italian Lopburi Regional Archaeological Project (LoRAP), founded in 1988 to study archaeology in the Lop Buri River Basin.
Before starting the excavation at the Khok Phutsa site, the team created a map of the area. They selected two vacant lots where there were no sugar-apple trees. The size of the first pit is 4x4m and the second, 3x2m. They are a little bit far from each other.











Iron Age burials discovered in central Thailand
Armbands of multiple bangles made of tin and bronze were found on the wrists
of an adult’s skeleton at Phu Noi site in Ban Mi district
[Credit: Karnjana Karnijanatawe]

While working on each pit, they gradually removed the soil inch by inch until they reached to the natural layer of soil where there is no evidence of anthropogenic activity.


«I was thrilled when we found a human skeleton during the first month of excavation. The depth was only 1.5m,» said Sorathach.











Iron Age burials discovered in central Thailand
Collections of pottery dating back to the Iron Age found in Lop Buri. The items are displayed in the exhibition
at King Narai National Museum in Lop Buri [Credit: Karnjana Karnijanatawe]

After the human bones were found, the team removed dirt by using smaller and softer tools like archaeology brushes. Later, they discovered the whole skeleton. It was straight with the face up. But the team can’t yet tell if it’s a he or a she.
When they finished digging the first pit, they found two skeletons. There was broken pottery beside the bodies. They also found a clay pot, not broken, next to the feet.











Iron Age burials discovered in central Thailand
Beads made from giant clam shells [Credit: The Fine Arts Department]

Currently, the team is working on the second pit at the Khok Phutsa site. Besides the skeletons found in both pits, the team has found shells of giant clams and ornaments made from them, such as broken bangles and beads. Axes made from the shells of giant clams were also found.


«The evidence showed that the area used to be a community where people knew how to create products from giant clams. The species lives on corals, but its shells are found on land. It confirms the old knowledge that the area of Lop Buri and other provinces in the Central Region were part of the sea 8,000 years ago,» he said.











Iron Age burials discovered in central Thailand
A clay whistle, which may have been a musical instrument used by people in the Iron Age. The artefact
was found in Tha Kae site in Muang district [Credit: The Fine Arts Department]

The team found additional artefacts belonging to people from other periods. These include small, loaf-shape skin-rubbing stones, stone axes, drum-shaped ear-studs, clay beads and pottery.
«The items show that people have lived in the area of the Khok Phutsa site since the New Iron Age to the Dvaravati period [6th-11th century]. If we look around, we will see that the site is located in a Muslim community. It means that people have lived in the area from prehistorical times until today,» he said.











Iron Age burials discovered in central Thailand
Carbonised rice grains [Credit: Karnjana Karnijanatawe]

All artefacts found in the two pits will be removed. Some items will be further studied in the laboratory to date them accurately, while the human bones will be extracted to get DNA. The information will also help discover if people migrated during ancient times.


The team expects to finish excavation and remove all artefacts before the monsoon season. They will cover the pits and return the site to the owner, as there is no plan to develop Khok Phutsa to be a new tourist attraction in Lop Buri.











Iron Age burials discovered in central Thailand
Dr Fiorella Rispoli, left, and Dr Roberto Ciarla, middle, the Italian archaeologists, excavated
the first pit of the Khok Phutsa site [Credit: The Fine Arts Department]

«We only need to collect all items we found at the site because every artefact is important evidence letting us know our history. It tells us how people lived their lives in the area that we live in today,» he concluded.


Author: Karnjana Karnijanatawe | Source: Bangkok Post [April 12, 2019]



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14th century castle walls unearthed during roadworks in Orkney

A team from ORCA Archaeology unearthed sections of wall and cobbled surface this week while undertaking a watching brief for an Orkney Islands Council infrastructure project in the centre of Kirkwall.











14th century castle walls unearthed during roadworks in Orkney
The ORCA Archaeology team working in challenging weather conditions at the site
[Credit: ORCA Archaeology]

To date, three walls in total have been uncovered during the works. One substantial wall set back from the road junction is built using immense stone blocks and lime mortar indicating that it is part of the now demolished fourteenth-century Kirkwall Castle.
The castle itself was built without royal consent in the late fourteenth century by Earl Henry Sinclair while Orkney was still ruled by Scandinavian kings and was said to be one of the strongest castles in the realm. In the early seventeenth century the castle saw action when it was defended by the rebellious Stewart Earls against the Scottish King’s forces under the Earl of Caithness. The structure was so strong that cannon balls were said to “split like wooden golf balls against the walls”!











14th century castle walls unearthed during roadworks in Orkney
Cobbled surface unearthed in Castle Street 
[Credit: ORCA Archaeology]

Following the siege, an order was given by the Scottish King James VI to dismantle the castle in 1615 so that it could not be used again as a centre of rebellion. This process of destruction was completed in 1865 when the remaining structure was demolished to make way for Castle Street.
There are now no visible signs of this immense fortification to be seen above ground, although previous building works in the 1980s revealed massive stone walls close to the present site which most likely were the foundations of the castle.



While the ORCA Archaeology team continues to dig the fascinating and substantial finds, the road project continues.


Pete Higgins, Senior Project Manager ORCA Archaeology commented, “ This is an area of the city that we know was the site of the castle and it is exciting to see the remains of the possible curtain wall and part of the fourteenth-century Kirkwall Castle in situ..”

The whole site will be recorded, added to the historical archive and covered over again so that the infrastructure works can progress without delay.


Source: Orkney Research Centre for Archaeology [April 12, 2019]



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16th century coin hoard found in Slovakia

Archaeologists have been researching interesting findings in the Liptov region. A married couple during a hike to the Choč mountain near Likavka made a great discovery of silver and two golden coins from the turn of 15th and 16th century, My Liptov wrote.











16th century coin hoard found in Slovakia
Credit: Martin Furman

The husband saw the coins in terrain that was dug out by boars. They did not touch it, but immediately contacted archaeologists. They waited for three hours at the spot.
Archaeologists and preservationists are used to people who come to their offices and literally pour the coins on the table. The discovery near Likavka is unique and precious because experts have the opportunity to observe it at the spot of the finding. Coins were collected from an area of about two square metres.











16th century coin hoard found in Slovakia
Credit: Martin Furman

In the shallow hole, there was the broken clay bottom of a jug with coins that were, thanks to corrosion, attached to the remains of the fabric on the inner side of the jug. Nearby, there was a metal pot-lid.


The treasure was covered by a fine layer of soil. We can assume that the person who covered the coins was in hurry. The treasure was located near to an historical trade road.











16th century coin hoard found in Slovakia
Credit: Martin Furman

Martin Furman from Regional Monuments Board Žilina who was also in the team of experts who worked on the spot talked about the treasure as of the most beautiful archaeological discovery in his professional life.
We can only guess who and why hid the coins into the ground. Neither the archaeologists have a clear answer.











16th century coin hoard found in Slovakia
Credit: Martin Furman

“There could be several reasons. It is the treasure hidden either in 1527 or shortly after this year, or it at least looks like that by now. It is probably linked to turbulent year of civil war between Ferdinand of Habsburg and John Zápolya who were fighting to gain the Hungarian throne,” Furman explained, as quoted by My Liptov.


Furman also pointed out that labourer earned between 6 and 10 silver coins per day in 16th century. “It is literary a fortune. Ordinary person could only hardly gain a golden coin.”











16th century coin hoard found in Slovakia
Credit: Martin Furman

The public will have also the possibility to see the treasure from Likavka. However, people should be patient as there are many steps to be taken before it finally get into the Museum of Liptov in Ružomberok.
Historical value of the treasure is unquantifiable, the economic price wil l be given by experts. The married couple will get a reward, as the law said. Monument Board should approve it and in this case, they can look forward to the full finding value.











16th century coin hoard found in Slovakia
Credit: Martin Furman

“If a finder act in accordance with monuments law and let the finding at the spot and call the representatives of the monuments board who will pick up the finding using the methods of archaeological research, he or she has a right to finder’s reward of 100 percent of the finding given by an expert,” explained Furman, as quoted by My Liptov.


In this case, all the requirements were fulfilled. “During my 13-year-long practice in Žilina, I haven’t experienced anything like that.”











16th century coin hoard found in Slovakia
Credit: Martin Furman

Furman dedicates his time of archaeologists also to numismatics. When he received the call, he was in upper Orava region and it took three hours to get to the spot on Saturday. His colleague Barbora Danielová from Orava Museum also helped when she left everything what she was doing, picked up the needed tools and went to the spot to document the treasure.


Source: The Slovak Spectator [April 12, 2019]



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Archaeologists begin re-excavating hidden Roman bath at the Roman Baths

The bath was first discovered and excavated 130 years ago, but was then quickly back-filled and poorly recorded.











Archaeologists begin re-excavating hidden Roman bath at the Roman Baths
Period 1 plunge bath, Roman Baths [Credit: Cotswold Archaeology]

Measuring 4 metres x 5 metres, it is one of eight baths known at the Roman Baths site and is beneath York Street next to the main suite of baths.
Stephen Clews, Manager of the Roman Baths, said: “The excavation of this bath is part of the most significant archaeological investigations to have taken place at the Roman Baths for more than 30 years. It is helping us to build a picture of what was happening on the south side of the site, where it has been very difficult to gain access in the past.”











Archaeologists begin re-excavating hidden Roman bath at the Roman Baths
Period 1 plunge bath, Roman Baths [Credit: Cotswold Archaeology]

The excavation of the bath is part of a wider programme of investigation taking place as part of the National Lottery funded Archway Project, which is creating a new Clore Learning Centre for the Roman Baths and a World Heritage Centre for the city. The position of the bath means that it cannot be seen by visitors on a normal visit to the Roman Baths.
The excavation is being carried out for the Roman Baths by Cotswold Archaeology. The Archway Project is run by Bath & North East Somerset Council, which owns and operates the Roman Baths, with the support of The National Lottery Heritage Fund, The Clore Duffield Foundation, The Roman Baths Foundation, the Garfield Weston Foundation and hundreds of other supporters and donors.


Aquae Sulis was a small town in the Roman province of Britannia that is now modern day Bath. The Romans had probably arrived in the area shortly after their arrival in Britain in AD 43 and there is evidence that their military road, the Fosse Way, crossed the river Avon at Bath.
Not far from the crossing point of their road, they would have been attracted by the large natural hot spring which had been a shrine of the Celtic Brythons, dedicated to their goddess Sulis.



This spring is a natural mineral spring found in the valley of the Avon River in Southwest England, it is the only spring in Britain officially designated as hot. The name is Latin for “the waters of Sulis.”


The Romans identified the goddess with their goddess Minerva and encouraged her worship that helped the native populations adapt to Roman culture. The spring was built up into a major Roman Baths complex associated with an adjoining temple. About 130 messages to Sulis scratched onto lead curse tablets (defixiones) have so far been recovered from the Sacred Spring by archaeologists.


Source: The Roman Baths [April 13, 2019]



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Dental analysis suggests Hyksos ‘invasion’ arose from outsiders marrying into...

Archaeologists have found another confirmation that the Hyksos, who ruled ancient Egypt in 1650-1540 BC, did not conquer the country, but emigrated from the east. Apparently, Hyksos women married Egyptian nobles, and their descendants gradually expelled the local elite. The results of the research were presented at the 88th annual conference of the American Society of Physical Anthropology.











Dental analysis suggests Hyksos 'invasion' arose from outsiders marrying into power
View of excavations at Tell el-Dab’a/Avaris, the ancient capital of the Hyksos empire
[Credit: Bournemouth University]

The Hyksos were tribes (possibly of Semitic origin), which appeared in northern Egypt during the reign of the Pharaohs of the XIII dynasty, before 1650 BCE. Little is known about them, and what has reached us comes mainly from the works of historians that were written more than a thousand years after their disappearance, or from rare preserved sources from the era of the Egyptians’ struggle against them.


The Hyksos


Ancient historians represent the Hyksos hordes as invaders who seized part of the country. They brought with them new types of war chariots, swords, daggers, metal helmets, and shields. However, some modern historians and archaeologists believe that there was no military invasion, but rather a peaceful migration. There is very little evidence of war or battles that would have occurred in the territory of Egypt at that time. Proponents of this theory believe that the pharaohs of the 13th dynasty were weak rulers and could not prevent the emergence of large numbers of immigrants.


The Hyksos founded the 15th dynasty, which reigned in the northern and central part of the country. At the same time, southern Egypt came under the control of the Pharaohs of the XVI-XVII Dynasties. The last pharaohs of the seventeenth Dynasty began a war against the Hyksos, and in about 1540 BC they expelled the last of their kings from the country. After this, Ahmose I, who founded the XVIII Dynasty, became ruler of the country.











Dental analysis suggests Hyksos 'invasion' arose from outsiders marrying into power
Ahmose I depicted fighting back the Hyksos [Credit: WikiCommons]

The capital of the Hyksos state was the city of Avaris, located in the Nile Delta. It was inhabited from approximately 1780 until 1550 BC, until the moment when Ahmose expelled the Hyksos from the country and destroyed their capital.
Today Avaris is called Tel el Daba, and archaeological work has unearthed the tombs of the local elite, created in the style of Canaan, in which burial gifts have also been preserved.


Invasion by Marriage


Archaeologists Christina Stantis and Holger Schutkowski of Bournemouth University (United Kingdom) now suggest that women who married Egyptian nobles first appeared in eastern Egypt, and their descendants gradually expelled the local elite. Scientists analyzed strontium and oxygen isotopes in the remains of 71 people buried in Avaris. About half of them died before the appearance of the Hyksos in Egypt, and half during their rule.


From the ratio of oxygen isotopes and strontium in the teeth, one can determine from which area a person originated. As a baseline, scientists analyzed the proportions of isotopes in animal bones found in Tel al-Daba, as well as samples of local livestock and shells.


It turned out that of the 27 women who lived in Avaris shortly before the appearance of the Hyksos, 21 were not from the Nile Valley, but from other locations. At the same time, almost all the noble men who died at this time were local natives. Scientists believe their results confirm the scenario in which, shortly before the migration began, Hyksos women married members of the local elite.


Source: N+1 [April 13, 2019]



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Iron Age settlement and ‘ritual burials’ discovered in Oxfordshire

A multi-million pound Thames Water project to protect the future of a rare Oxfordshire chalk stream has revealed some fascinating and gruesome discoveries dating back almost 3,000 years.











Iron Age settlement and 'ritual burials' discovered in Oxfordshire
This is believed to be a female skeleton buried with feet cut off and placed by side
 with arms bound behind head [Credit: Cotswold Archaeology]

An ancient settlement was found containing an array of historic artefacts while preparing to lay new water pipes which will relieve pressure on the precious Letcombe Brook, near Wantage.
Among the important finds were 26 human skeletons believed to be from the Iron Age and Roman periods, and some likely to have been involved in ritual burials, along with evidence of dwellings, animal carcases and household items including pottery, cutting implements and a decorative comb.











Iron Age settlement and 'ritual burials' discovered in Oxfordshire
Skeleton uncovered with skull placed at its feet
[Credit: Cotswold Archaeology]

Cotswold Archaeology has now carefully removed the items for forensic examination, allowing Thames Water to start laying the six kilometre pipe which, following consultation with residents, will supply nearby villages with water taken from groundwater boreholes near the River Thames and not Letcombe Brook.


Neil Holbrook, chief executive of Cotswold Archaeology, said: “The new Thames Water pipeline provided us with an opportunity to examine a number of previously unknown archaeological sites.











Iron Age settlement and 'ritual burials' discovered in Oxfordshire
Smashed up Iron Age pottery (c.700 — 400 BC)
[Credit: Cotswold Archaeology]

“The Iron Age site at Childrey Warren was particularly fascinating as it provided a glimpse into the beliefs and superstitions of people living in Oxfordshire before the Roman conquest. Evidence elsewhere suggests that burials in pits might have involved human sacrifice.
“The discovery challenges our perceptions about the past, and invites us to try to understand the beliefs of people who lived and died more than 2,000 years ago.”











Iron Age settlement and 'ritual burials' discovered in Oxfordshire
Late Roman or Anglo Saxon bone comb
[Credit: Cotswold Archaeology]

Paolo Guarino, Cotswold Archaeology project officer, added: “These findings open a unique window into the lives and deaths of communities we often know only for their monumental buildings, such as hillforts or the Uffington White Horse.


“The results from the analysis of the artefacts, animal bones, the human skeletons and the soil samples will help us add some important information to the history of the communities that occupied these lands so many years ago.”











Iron Age settlement and 'ritual burials' discovered in Oxfordshire
Bronze brooch (Roman) was discovered by one of the workers
at the dig site [Credit: Cotswold Archaeology]

Chris Rochfort, Thames Water environmental manager, said: “We’ve found significant historical items on many previous upgrade projects but this is one of our biggest and most exciting yet.
“This is a £14.5m project which is going to have real benefits for the environment by reducing the need to take water from the Letcombe Brook, a chalk stream which is a globally rare and highly important habitat for us to protect. As a result, future generations will be able to enjoy it for years to come – and now they can also learn about their village’s secret history.”











Iron Age settlement and 'ritual burials' discovered in Oxfordshire
The dig site near Letcombe Bassett where the remains were discovered
[Credit: Cotswold Archaeology]

The archaeological findings have already been shared with residents at events in Letcombe Bassett and Letcombe Regis village halls.


Source: Thames Water [April 14, 2019]



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‘Too Far North’ Poetry PamphletA new poetry selection coming…


‘Too Far North’ Poetry Pamphlet


A new poetry selection coming soon! All rights reserved, 2019.


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‘An Economy Of Stones’ Poetry Reading and Interactive Exhibition…


‘An Economy Of Stones’ Poetry Reading and Interactive Exhibition at Ebor Studios and Gallery Frank, Littleborough, North Manchester on Saturday, 20th of July 2019 from 7.00pm until 8.000pm. Doors open at 6.45pm. Tickets available via Eventbrite. Hope you can join us!


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NASA’s Cassini Reveals Surprises with Titan’s Lakes


NASA & ESA — Cassini Mission to Saturn & Titan patch.


April 16, 2019


On its final flyby of Saturn’s largest moon in 2017, NASA’s Cassini spacecraft gathered radar data revealing that the small liquid lakes in Titan’s northern hemisphere are surprisingly deep, perched atop hills and filled with methane.


The new findings, published April 15 in Nature Astronomy, are the first confirmation of just how deep some of Titan’s lakes are (more than 300 feet, or 100 meters) and of their composition. They provide new information about the way liquid methane rains on, evaporates from and seeps into Titan — the only planetary body in our solar system other than Earth known to have stable liquid on its surface.



Image above: This near-infrared, color view from Cassini shows the sun glinting off of Titan’s north polar seas. Image Credits: NASA/JPL-Caltech/Univ. Arizona/Univ. Idaho.


Scientists have known that Titan’s hydrologic cycle works similarly to Earth’s — with one major difference. Instead of water evaporating from seas, forming clouds and rain, Titan does it all with methane and ethane. We tend to think of these hydrocarbons as a gas on Earth, unless they’re pressurized in a tank. But Titan is so cold that they behave as liquids, like gasoline at room temperature on our planet.


Scientists have known that the much larger northern seas are filled with methane, but finding the smaller northern lakes filled mostly with methane was a surprise. Previously, Cassini data measured Ontario Lacus, the only major lake in Titan’s southern hemisphere. There they found a roughly equal mix of methane and ethane. Ethane is slightly heavier than methane, with more carbon and hydrogen atoms in its makeup.


«Every time we make discoveries on Titan, Titan becomes more and more mysterious,» said lead author Marco Mastrogiuseppe, Cassini radar scientist at Caltech in Pasadena, California. «But these new measurements help give an answer to a few key questions. We can actually now better understand the hydrology of Titan.»


Adding to the oddities of Titan, with its Earth-like features carved by exotic materials, is the fact that the hydrology on one side of the northern hemisphere is completely different than the that of other side, said Cassini scientist and co-author Jonathan Lunine of Cornell University in Ithaca, New York.


«It is as if you looked down on the Earth’s North Pole and could see that North America had completely different geologic setting for bodies of liquid than Asia does,» Lunine said.


On the eastern side of Titan, there are big seas with low elevation, canyons and islands. On the western side: small lakes. And the new measurements show the lakes perched atop big hills and plateaus. The new radar measurements confirm earlier findings that the lakes are far above sea level, but they conjure a new image of landforms — like mesas or buttes — sticking hundreds of feet above the surrounding landscape, with deep liquid lakes on top.



Image above: Artist’s conception of Cassini winging by Saturn’s moon Titan (right) with the planet in the background. Image Credits: NASA/JPL-Caltech.


The fact that these western lakes are small — just tens of miles across — but very deep also tells scientists something new about their geology: It’s the best evidence yet that they likely formed when the surrounding bedrock of ice and solid organics chemically dissolved and collapsed. On Earth, similar water lakes are known as karstic lakes. Occurring in in areas like Germany, Croatia and the United States, they form when water dissolves limestone bedrock.


Alongside the investigation of deep lakes, a second paper in Nature Astronomy helps unravel more of the mystery of Titan’s hydrologic cycle. Researchers used Cassini data to reveal what they call transient lakes. Different sets of observations — from radar and infrared data — seem to show liquid levels significantly changed.


The best explanation is that there was some seasonally driven change in the surface liquids, said lead author Shannon MacKenzie, planetary scientist at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland. «One possibility is that these transient features could have been shallower bodies of liquid that over the course of the season evaporated and infiltrated into the subsurface,» she said.


These results and the findings from the Nature Astronomy paper on Titan’s deep lakes support the idea that hydrocarbon rain feeds the lakes, which then can evaporate back into the atmosphere or drain into the subsurface, leaving reservoirs of liquid stored below.


Cassini, which arrived in the Saturn system in 2004 and ended its mission in 2017 by deliberately plunging into Saturn’s atmosphere, mapped more than 620,000 square miles (1.6 million square kilometers) of liquid lakes and seas on Titan’s surface. It did the work with the radar instrument, which sent out radio waves and collected a return signal (or echo) that provided information about the terrain and the liquid bodies’ depth and composition, along with two imaging systems that could penetrate the moon’s thick atmospheric haze.


The crucial data for the new research were gathered on Cassini’s final close flyby of Titan, on April 22, 2017. It was the mission’s last look at the moon’s smaller lakes, and the team made the most of it. Collecting echoes from the surfaces of small lakes while Cassini zipped by Titan was a unique challenge.


«This was Cassini’s last hurrah at Titan, and it really was a feat,» Lunine said


The Cassini-Huygens mission is a cooperative project of NASA, ESA (European Space Agency) and the Italian Space Agency. NASA’s Jet Propulsion Laboratory, a division of Caltech in Pasadena, California, manages the mission for NASA’s Science Mission Directorate, Washington. JPL designed, developed and assembled the Cassini orbiter. The radar instrument was built by JPL and the Italian Space Agency, working with team members from the U.S. and several European countries.


More information about Cassini can be found here: https://solarsystem.nasa.gov/cassini


Images (mentioned), Text, Credits: NASA/JoAnna Wendel/JPL/Gretchen McCartney.


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NEOWISE Celebrates Five Years of Asteroid Data


NASA — NEOWISE Mission logo.


April 16, 2019


NASA’s Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE) mission released its fifth year of survey data on April 11, 2019. The five years of NEOWISE data have significantly advanced scientists’ knowledge of asteroids and comets in the solar system, as well as the stars and galaxies beyond.


The data from all five years of the survey are available at: http://wise2.ipac.caltech.edu/docs/release/neowise/.



Animation above: Comet C/2018 Y1 Iwamoto as imaged in multiple exposures of infrared light by the NEOWISE space telescope. The infrared images were taken on Feb. 25, 2019, when the comet was about 56 million miles, or 90 million kilometers, from Earth. C/2018 Y1 Iwamoto is a long-period comet originally from the Oort Cloud and coming in near the Sun for the first time in over 1,000 years. Animation Credits: NASA/JPL-Caltech.


«NEOWISE recently surpassed 95 billion recorded measurements of asteroids, comets, stars and galaxies — a remarkable accomplishment for a recycled spacecraft,» said Lindley Johnson, NASA’s planetary defense officer and head of the Planetary Defense Coordination Office at NASA Headquarters in Washington. «This asteroid hunter has measured the sizes of more than 1,000 near-Earth asteroids and is still producing great data, making it a unique asset in our portfolio of asteroid-hunting telescopes and an important prototype for an upcoming space-based NEO survey mission.»


In addition to providing critical data on asteroids and comets in our own solar system, NEOWISE has provided data that have enabled the worldwide scientific community to track bursting stars, characterize distant quasars from the first billion years of the universe’s history, conduct a census of millions of merging galaxies and take multi-wavelength measurements of hundreds of millions of stars and galaxies.


«The data from NEOWISE effectively give us a movie of the universe as it changes over time at infrared wavelengths, which is now being used in over 1,000 different astronomical publications,» said Amy Mainzer, NEOWISE principal investigator at NASA’s Jet Propulsion Laboratory in Pasadena, California.


From WISE to NEOWISE


Originally called the Wide-field Infrared Survey Explorer (WISE), the spacecraft was launched in December 2009 to study galaxies, stars and solar system bodies by imaging the the infrared light in the entire sky. It was placed in hibernation in 2011 after completing its primary astrophysics mission. In September 2013, the spacecraft was reactivated, renamed NEOWISE and assigned a new mission: to assist NASA’s efforts to identify and characterize the population of near-Earth objects. NEOWISE is also characterizing more distant populations of asteroids and comets to provide information about their sizes and compositions.




NEOWISE asteroids hunter. Image Credits: NASA/JPL

The NEOWISE survey will end when its changing orbit eventually prevents it from obtaining high-quality data. But until that time, NEOWISE will continue to contribute valuable data both to humanity’s record of the universe around us and to the search for asteroids that pose a hazard to Earth.


NASA’s Jet Propulsion Laboratory in Pasadena, California, manages and operates the NEOWISE mission for NASA’s Planetary Defense Coordination Office within the Science Mission Directorate in Washington. The Space Dynamics Laboratory in Logan, Utah, built the science instrument. Ball Aerospace & Technologies Corp. of Boulder, Colorado, built the spacecraft. Science data processing takes place at IPAC at Caltech in Pasadena. Caltech manages JPL for NASA.


For more information about NEOWISE, visit: https://www.nasa.gov/neowise and http://neowise.ipac.caltech.edu/


For more information about asteroids and near-Earth objects, visit: https://www.jpl.nasa.gov/asteroidwatch


Images (mentioned), Text, Credits: NASA/JoAnna Wendel/JPL/DC Agle.


Best regards, Orbiter.chArchive link


ancientanimalart: Boar protome from a yoke fitting 2nd century…


ancientanimalart:



Boar protome from a yoke fitting


2nd century CE


According to the description at the source, it seems that the Celts originated the use of the front half of a boar in designs like this and the Romans adopted it from them to use on horse harnesses. This object uses the tip of an elephant’s tusk where normally one would find a boar’s tusk, thus (according to the source), it “imitates a supernaturally large boar tooth.” They go on to say that there is no firm evidence for ivory crafting north of the Alps, so we can assume that this was created elsewhere. 


from Augusta Raurica (Augst, Switzerland)



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clevelandmuseumarchivist: Nikko, the Sun Bodhisattva, was…


clevelandmuseumarchivist:



Nikko, the Sun Bodhisattva, was Sherman Lee’s favorite work in the museum collection.


Nikko, the Sun Bodhisattva, c. 800s


Japan, Heian Period (794-1185)


wood, carved from one block of Japanese yew, Overall: h. 46.7 cm (18 3/8 in.). John L. Severance Fund 1961.48



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mini-girlz: Standing Female Figure Mexico, Guerrero, Mezcala 500…


mini-girlz:



Standing Female Figure


Mexico, Guerrero, Mezcala


500 B.C. — A.D. 1000


Stone Sculpture 


Height: 9 1/16 in. (23 cm)


Art of the Ancient Americas



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Bought this and it’s a hugely enjoyable read; handy for the car too!

Bought this and it’s a hugely enjoyable read; handy for the car too!



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Carreg Coetan Arthur Prehistoric Burial Chamber, Newport, Wales, 12.4.19.


Carreg Coetan Arthur Prehistoric Burial Chamber, Newport, Wales, 12.4.19.










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