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Here’s How 12,000-Year-Old Weather Can Help Us Predict Future Changes in The Climate

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The end of the last ice age, around 12,000 years ago, was characterised by a final cold phase called the Younger Dryas. Scandinavia was still mostly covered in ice, and across Europe the mountains had many more, and larger, glaciers than today. There was a substantial icefield in the west of Scotland and glaciers could be found on many mountains across the British Isles.

 

Not surprisingly, the climate was colder back then, especially in winter, with temperatures in the UK getting down to -30°C or lower.

Despite these freezing ice-age winters, differences in the Earth’s orbit around the Sun meant the summers were relatively warm, with an average temperature in July between 7°C and 10°C across most of the UK and Ireland.

Then, as now, the polar front jet stream (a high-altitude fast-moving wind belt) had a major influence on the weather across Europe, bringing precipitation (rain and snow) from the Atlantic across the continent.

However, before the time of written climate records, the timing, quantity and pattern of precipitation are poorly understood.

Our new study has used glaciers that existed during the Younger Dryas to determine the precipitation patterns and path of the jet stream across Europe at that time.

We identified glacial landforms called moraines at 122 sites from Morocco in the south to Norway in the north, and from Ireland in the west to Turkey in the east, which demonstrated the presence of glaciers some 12,000 years ago.

 

We reconstructed the 3D geometry of each of these glaciers using knowledge of the way that ice flows across the landscape.

From the reconstructed ice surfaces, we could determine an important point on each of these glaciers, the equilibrium line altitude which is linked to climate via yearly precipitation and average summer temperature.

It is essentially the altitude on the glacier where snow accumulation and snow melt are equal at the end of September and can be seen as the snowline.

The results provided a map of precipitation across Europe about 12,000 years ago which was controlled by the jet stream.

Jet stream weather

What the results showed was that the UK, Ireland, Portugal, and Spain were mostly wetter than the present day, as was the Mediterranean, especially in the east – the Balkans, Greece, and Turkey.

It was relatively drier across much of France, Belgium, the Netherlands, Germany, and farther east across Europe. These areas of wetter and drier climate allowed us to identify the location of the jet stream.

We surmised that the jet stream passed over the wetter regions bringing with it the storms (known as mid-latitude depressions) we are all familiar with in the UK – especially Scotland – and also potentially generated other smaller, more intense storms.

 

Based on the path of the jet stream it is believed that the autumn and spring were wettest in the UK and Ireland and that the winters were drier.

Across Portugal, Spain, and the Mediterranean, the winter months were probably the wettest, with autumn and spring being somewhat drier.

This is the first time that we have had an insight into the seasonal weather patterns across Europe during the Younger Dryas, and indeed such glimpses of past climate, beyond the period for which we have recorded climate observations, are rare.

Normally it is only numerical climate models that reveal such a regional scale view on past atmospheric circulation, storm tracks, and precipitation.

Numerical climate models plot our weather and climate by dividing the atmosphere, Earth’s surface and ocean into multiple interconnected cells, vertically and horizontally, in a three-dimensional grid, and solve complex mathematical equations to determine how energy and matter move through the system.

Changing jet stream

In our study, a comparison of the glacier-derived precipitation from 12,000 years ago was made with the outputs from several palaeoclimate (the study of climate in the past) computer simulations.

Numerical climate models are extremely complex, yet they remain a simplification of reality, so different models inevitably generate outputs which variously agree and disagree.

 

The general pattern of precipitation determined from our study of the palaeo-glaciers agreed with some parts of the climate model outputs, but in disagreement with others – for example, none of the climate models identified all of the UK, Ireland, Portugal, Spain and Mediterranean as being wetter in the past.

We are already seeing signs that the jet stream may be changing as the climate warms and it is thought that it will probably move northwards and become wavier.

These ripples could lead to more extremes, for example, heatwaves in summer and more storms and flooding in the winter.

To understand how climate will change in the future we rely on computer models, but these models do not yet agree on what happened in the past nor on exactly what will happen in the future.

To make better future predictions from ongoing climate warming, palaeoclimate datasets, such as the glacier-derived precipitation determined from our study, can be used to test the computer models.

When the models can better reproduce precipitation patterns reconstructed from past climates, especially in periods when the jet stream has moved, then our confidence in their predictions of future climate will also be boosted.The Conversation

Brice Rea, Professor, Geography, University of Aberdeen.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

 



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Deep-Sea Coral Reefs Found Surviving in Ireland at The Edge of a Submarine Canyon

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Most people associate the word “coral” with sunshine, blue skies and Australia’s Great Barrier Reef. In fact, more than half of the 5,100 species on the planet exist as “cold-water corals” in deep and dark parts of the world’s oceans.

 

Unlike most other animals, corals are immobile and so rely heavily on currents to transport tiny bits of organic material to feed on.

Over time, in some cases millions of years, cold-water corals can grow to eventually form huge skyscraper-sized structures on the seabed called “coral mounds”.

These structures are common in the northeast Atlantic at the edge of the Irish continental shelf. They can be several kilometres long and reach 100 metres (328 feet) or more in height – taller than any building in Ireland.

I have been studying the cold-water coral habitats off the coast of Ireland for a number of years, and have found these mounds of fossilised coral and sediment are incredibly varied.

Some are completely covered with live coral while others have lots of dead coral on the surface, and the mounds themselves have very different shapes and sizes.

One place of interest is the Porcupine Bank Canyon, the largest submarine canyon at the edge of Ireland’s continental shelf. Colleagues and I wanted to understand why the coral there varied so much over short distances.

 

To do this, we used the Irish Marine Institute’s deepwater research submersible to gather sonar data and deploy monitoring systems.

This equipment is essential to retrieve information from habitats that can be found almost a kilometre (0.62 miles) beneath the surface. We recently published the results of our work in the Nature journal Scientific Reports.

Images show that corals are thriving at the very edge of the canyon on a near-vertical cliff face. Monitoring stations deployed nearby showed that the currents here were fast, sometimes more than a metre per second, the highest speed ever recorded in a cold-water coral habitat.

Nevertheless, there was also more coral rubble at these sites, which may be the result of these faster currents.

We then used video footage captured by the submarine to generate 3D reconstructions of the coral habitats which we could analyse to understand how deep water currents were influencing them.

Interestingly, while the corals can survive these extreme conditions, it appears that they still prefer it when the current slows down as they then find it easier to feed.

As the cold-water corals live in such remote parts of the planet, in the past experiments have been run in tanks in laboratories which show similar results.

As the world warms, so too will the oceans. Winds over the sea surface are getting stronger, causing average ocean currents to accelerate by around 5 percent per decade since the 1990s.

It’s still unclear exactly how these huge mounds of coral deep below the surface of the ocean will respond to these changing conditions, especially since coral lives on such long time scales. After all, these coral mounds grow very slowly, no more than a mere 12 centimetres (4.7 inches) every thousand years.

 

Yet despite their slow-growing nature, colleagues and I have previously found these mounds have exhibited changes over just four years, with increased amounts of coral rubble and significant decreases in the coverage of a particular coral species.

This is why our team recently deployed the monitoring stations for another year. We’re looking out for things like increased production of coral rubble, or growth of coral on the mounds.

Ultimately, our aim is to determine how these corals will respond to these tough and changing conditions in the long run. The Conversation

Aaron Lim, Post-doctoral Researcher, Marine Geoscience, University College Cork.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

 



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The Pandemic Has Made Dating Difficult, Even For a Rhinoceros

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A lonely rhinoceros at a Bangladesh zoo is looking for new love after losing her partner seven years ago, but pandemic travel restrictions are hampering her keeper’s attempts to play matchmaker.

 

Kanchi, a star attraction at the Bangladesh National Zoo, is at her most fertile age. But since the death of her male partner in 2014, she has been living on her own in her muddy pen in the northern suburb of the capital.

The malaise of Kanchi the rhino has become increasingly apparent to the two million-plus visitors a year at the Dhaka landmark. 

Kanchi refuses food and often snubs her carer Farid Mia, who hugs the rhino and scratches its neck and shoulders. 

The one-tonne vegetarian beast is served six kilograms (13 pounds) of rice bran and one kilo of chickpeas each day. 

“Her mood swings frequently. Sometimes she does not respond to my calls. It is mainly because she has grown up alone all these years,” Mia said. 

“I tell her that we will soon find her a male partner. But she is restless. She needs a partner desperately.” 

Abdul Latif, curator of the zoo, said the coronavirus pandemic had blocked recent efforts to bring in a male rhino from Africa.

“We know she feels lonely and we are trying our best to buy a suitable partner,” Latif told AFP. 

 

There has been more attention given to Kanchi, however, since the plight of Kaavan, the world’s loneliest elephant made international headlines in November. 

The Asian elephant, who had been alone since 2012, was moved from a zoo in Pakistan to a conservation park in Cambodia following an intervention from a global animal rights charity and singer Cher.

But the keepers in Dhaka do not want the same fate for Kanchi, who is now at her most fertile age. 

“A rhino can live up to 38 years in captivity. She has many more years to live here. So, it is our duty to find a partner,” said Latif. 

While she waits, Kanchi ambles around her pen and wallows in her mud spa. 

She also basks lazily in the sun, ignoring the multitudes who come to see the 3,000 animals at the zoo. 

“Her health is alright now, but I don’t know about the future,” said Mia. 

“She needs a partner badly and pretty soon.”

© Agence France-Presse

 



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The Pandemic Could Be Harming Kids’ Eyesight, But It Isn’t The Virus to Blame

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School closures are among the more controversial options for controlling the COVID-19 pandemic, with authorities debating whether the preventative measure is worth the potential educational, social, and emotional costs.

 

Researchers in China have uncovered yet another health concern faced by children kept in isolation for extended periods; deteriorating eyesight.

Short-sightedness – what is medically referred to as myopia – is already a concerning problem in East Asian countries, prompting China to make it a health priority in recent years.

One of its public programs is an annual eye exam for school children. Based on a diagnostic process called photoscreening, the system captures light-induced reflexes in each eye, giving technicians a snapshot of refractive errors or misalignments in crucial eye anatomy.

Researchers used photoscreening records from children in 10 Shandong elementary schools, all collected at the start of every school year since 2015.

With COVID forcing the closure of schools for the first half of 2020, a new school year was kicked off in June rather than the usual September. But the usual screening took place nonetheless, giving eye specialists and researchers a good look at the eyes of thousands of children aged six to 13.

All up, the five consecutive years of testing provided the scientists with a glimpse into a total of 389,808 eyeballs.

 

An analysis of the frequency of refractive errors found in all of those eyes revealed a relatively stable trend from 2015 to 2019, with perhaps a slight shift towards myopia.

That shift was unmistakable in 2020’s results though, with a substantial jump in errors that qualify as short-sightedness, significantly among six to eight year olds.

In fact, the prevalence of myopia in children aged six was three times more than in those of any previous year.

While we can only speculate over the cause of the widespread change, staring intently at books and screens for long periods while isolated indoors will do the trick just nicely.

“This substantial myopic shift was not seen in any other year-to-year comparison, making the cause possibly due to the unusual occurrence of home confinement in 2020,” the researchers suggest in their report.

It’s possible the fact the screening took place in June rather than September, together with all of the masking and distancing precautions that come with pandemic safety, just might have somehow affected the results.

But the differences weren’t consistent across all ages tested, making it unlikely confounding factors are to blame.

 

Just why some ages were more affected than others is a bit of a mystery. Given younger children were typically assigned fewer tasks to complete under home schooling, variations in screen-time or differences in amounts of near-sighted work probably aren’t enough to explain what’s going on.

 

Spending time outdoors is known to help, but again, it’s hard to argue that there’s any big difference between the amount of time six- and 13-year-olds spend outdoors.

What is looking likely is that six-year-olds are simply going through development that is more sensitive to environmental effects. It’s possible that with a longer window of isolation, even older children would soon face challenges with their sight.

“If that is the case, the period of environmental change may be the main risk factor for myopia development, with the younger children more sensitive to the environmental change than the older children,” the team writes.

“Children aged six to eight years may be experiencing an important period for myopia development.”

It’s a hypothesis that requires further research to confirm one way or another.

 

In any case, the results strongly suggests that spending copious amounts of time indoors during our childhood increases the risk to our vision.

This isn’t to say we need schools to be open for the sake of our children’s eyes. With the pandemic far from over, it’s important we do everything we can to save lives by isolating where necessary.

But knowing how isolation can affect our children’s development means we can take measures to reduce its impact.

Limiting screen time, keeping digital media half a metre away (at least 18 inches or so) from the face and spending time outside each day where possible could be enough to mitigate at least some of the effects isolation indoors has on sight.

COVID-19 has taken enough of a toll on humanity’s health. Our eyesight doesn’t need to be another cost.

This research was published in JAMA Ophthalmology.

 



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Astronomers Find an Astonishing ‘Super-Earth’ That’s Nearly as Old as The Universe

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It turns out that planets can live a very long time indeed.

Around one of the galaxy’s oldest stars, an orange dwarf named TOI-561 just 280 light-years away, astronomers have found three orbiting exoplanets – one of which is a rocky world 1.5 times the size of Earth, whipping around the star on a breakneck 10.5-hour orbit.

 

Obviously an exoplanet so close to its star isn’t likely to be habitable, even if it is rocky like Earth, Venus and Mars. It would have a temperature of 2,480 Kelvin, tidally locked with a magma ocean on the permanent day side.

But the TOI-561 system, planets and all, is one of the oldest ever seen, at an estimated age of around 10 billion years.

That’s more than twice as old as the Solar System, nearly as old as the Universe itself, and evidence that rocky exoplanets can remain stable for a very long time.

“TOI-561 b is one of the oldest rocky planets yet discovered,” said astronomer Lauren Weiss of the University of Hawai’i.

“Its existence shows that the universe has been forming rocky planets almost since its inception 14 billion years ago.”

The three planets, named TOI-561 b, TOI-561 c and TOI-561 d, were identified by NASA’s planet-hunting space telescope, TESS. TESS stares at sections of the sky, looking for periodic, faint dips in the light of distant stars. These are transits, when a planet passes between us and its star.

 

From this data, and follow-up observations, astronomers were able to determine the orbital periods and sizes of the three exoplanets.

TOI-561 d, the outermost, is around 2.3 times the size of Earth, with an orbital period of 16.3 days. TOI-561 c is 2.9 times the size of Earth, with an orbital period of 10.8 days. And TOI-561 b is 1.45 times the size of Earth, with an orbital period of just over 10.5 hours.

The team also conducted radial velocity measurements. As planets orbit a star, that star doesn’t sit still. Each exoplanet exerts its own gravitational tug on the star, resulting in a little complex dance that compresses and stretches the star’s light as it moves towards and away from us as we observe it.

If we know the mass of the star, we can observe how much the star moves in response to an exoplanet’s gravitational tugging and calculate the mass of the exoplanet. From this, the researchers calculated that TOI-561b is about three times the mass of Earth.

But its density is about the same as Earth’s, about five grams per cubic centimetre.

 

“This is surprising because you’d expect the density to be higher,” said planetary astrophysicist Stephen Kane of the University of California, Riverside. “This is consistent with the notion that the planet is extremely old.”

That’s because the heavier elements in the Universe – metals heavier than iron – are forged in the hearts of stars, in the supernovae at the end of a massive star’s life, and collisions between massive dead stars. Only once stars have died and spread these elements out into space can they be taken up into other objects.

So, the very oldest stars in the Universe are very poor in metals. TOI-561, for instance, is low in metallicity. And any planets that formed in the earlier Universe should likewise have low metallicity.

Previous research has suggested that there is a lower metallicity limit for rocky planet formation, since heavier elements are less likely to be evaporated by stellar radiation, the grains surviving long enough in the circumstellar disc to clump together and form planets.

Finding planets like TOI-561 b can help constrain those models, which in turn could help us locate more ancient rocky exoplanets.

“Though this particular planet is unlikely to be inhabited today,” Kane said, “it may be a harbinger of a many rocky worlds yet to be discovered around our galaxy’s oldest stars.”

And this can aid us in the search for habitable worlds. Earth is around 4.5 billion years old; the earliest signs of life are thought to be about 3.5 billion years old. And yet vertebrates didn’t appear on the fossil record until about 500 million years ago, give or take.

Complex life as we know it takes time to emerge. So if we want to find life more complex than archaea or microbes, planets that are long-lived and relatively stable will be, scientists think, the most likely to be hospitable.

So while TOI-561 b wouldn’t be a nice place to visit, it constitutes yet another clue that could help us in our avid search for other life out there in the Universe.

The team’s research was presented at the 237th meeting of the American Astronomical Society. It has also been accepted into The Astronomical Journal, and is available on arXiv.

 



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Earliest Animal Cave Art on Record Has Been Found in Indonesia, And It’s Adorable

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The oldest-known animal drawing in the world is a 45,500-year-old depiction of a hairy, warty pig on a cave wall in Indonesia, a new study finds.

The mulberry colored painting, drawn with the red mineral ochre, shows the profile of what is likely a Sulawesi warty pig (Sus celebensis), a wild stubby-legged beast with facial warts that can weigh up to nearly 190 pounds (85 kilograms).

 

These pigs “are still found there today, although in ever-dwindling numbers,” said study co-lead researcher Adam Brumm, a professor of archaeology at Griffith University’s Australian Research Centre for Human Evolution.



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Dire Wolves May Have Been Lonely Survivors of an Ancient Lineage

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The ancient, extinct dire wolf may have been among the lonest of the wolves – so genetically distinct from its closest wolf relative that it could no longer interbreed, forcing it into an evolutionary dead end when it died out 13,000 years ago.

 

That’s the finding based on a new study, the in-depth analysis of DNA retrieved from ancient dire wolf bones from across North America. Once dire wolves (Canis dirus) diverged from grey wolves millions of years ago, they seem to have never mingled since.

In fact, so different is their genetic lineage from other canids that the research team proposes that dire wolves be placed in another genus completely – that they be reclassified as Aenocyon dirus, as was first proposed all the way back in 1918.

“Dire wolves are sometimes portrayed as mythical creatures – giant wolves prowling bleak frozen landscapes – but reality turns out to be even more interesting,” said palaeobiologist Kieren Mitchell of the University of Adelaide in Australia.

“Despite anatomical similarities between grey wolves and dire wolves – suggesting that they could perhaps be related in the same way as modern humans and Neanderthals – our genetic results show these two species of wolf are much more like distant cousins, like humans and chimpanzees.”

Dire wolf remains can be found in the fossil record from 250,000 to around 13,000 years ago, and seem to have dominated the carnivore scene during the last Ice Age in what is now North America.

 

In the famous La Brea tar pits alone, excavated dire wolf individuals outnumber the slightly smaller grey wolf (Canis lupus) more than a hundredfold.

But how they diverged, evolved and ultimately went extinct towards the end of the Last Glacial Period, about 11,700 years ago, has been challenging to piece together. So an international team of scientists set to work on one of the only clues we have: bones.

“Dire wolves have always been an iconic representation of the last ice age in the Americas, but what we know about their evolutionary history has been limited to what we can see from the size and shape of their bones,” said archaeologist Angela Perri of Durham University.

But sometimes palaeontological remains can contain other information inside: DNA preserved well enough to be sequenced. And that’s what the team investigated.

They obtained five samples of dire wolf DNA from over 50,000 years ago to 12,900 years ago, from Idaho, Ohio, Wyoming and Tennessee, and sequenced them.

Then, they compared them to genomic data from eight canids that are living today, obtained from a genomic database: grey wolf, coyote (Canis latrans), African wolf (Canis lupaster), dhole (Cuon alpinus), Ethiopian wolf (Canis simensis), African wild dog (Lycaon pictus), Andean fox (Lycalopex culpaeus) and grey fox (Urocyon cinereoargenteus).

 

They also generated new genome sequences for the grey wolf, the black-backed jackal (Canis mesomelas) and the side-striped jackal (Canis adustus).

They found that, unlike other wolves that migrated between regions, the dire wolf stayed put, never straying out of North America.

And, fascinatingly, even though they shared space with coyotes and grey wolves for at least 10,000 years, they never seem to have interbred with them to produce hybrids.

“When we first started this study, we thought that dire wolves were just beefed-up grey wolves, so we were surprised to learn how extremely genetically different they were, so much so that they likely could not have interbred,” said molecular geneticist Laurent Frantz of Ludwig Maximilian University in Germany and Queen Mary University in the UK.

“This must mean that dire wolves were isolated in North America for a very long time to become so genetically distinct.”

In fact, according to the team’s analysis, the dire wolves and grey wolves must have diverged from a common ancestor more than 5 million years ago. When you consider that dogs and wolves diverged between 15,000 and 40,000 years ago, that’s a very long time indeed.

Interbreeding between canid species whose territories overlap is quite common. The hybrid of a coyote and a wolf is so common that it has a name – coywolf – and wolf-dog hybrids aren’t unknown either (although breeding them as pets is extremely controversial in the US). So for dire wolves to have spent so long in proximity with canids without interbreeding is highly unusual.

And, although the team did not explore this possibility, the genetic isolation could have contributed to the ancient beast’s eventual demise, as it was unable to adapt to a changing world with new traits.

“While ancient humans and Neanderthals appear to have interbred, as do modern grey wolves and coyotes, our genetic data provided no evidence that dire wolves interbred with any living canine species,” Mitchell said. “All our data point to the dire wolf being the last surviving member of an ancient lineage distinct from all living canines.”

The research has been published in Nature.

 



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Every 8 Years, Swarms of Millipedes Stop Trains in Japan. Scientists Finally Know Why

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Every eight years during fall, a plague of millipedes swarm train lines in mountainous Japan, earning them the nickname ‘train millipedes’.

Working together, these small beasties (around 3 cm or 1.18 inches long) – which play a large role cycling nitrogen in Japan’s larch forests – have forced trains to come to a skidding halt.

 

Up until now, scientists weren’t quite sure what was causing them to swarm with such peculiar regularity, but a 50-year research project has finally confirmed that the species – Parafontaria laminata armigera (P. l. a.) – exists on a rare eight-year life cycle.

This confirmation is incredibly exciting, as cicadas are the only other known periodical animals with lifespans this long.

“This millipede needs seven years from egg to adult and one more year for maturation,” the team writes in their new paper.

“Thus, the eight-year periodicity of P. l. a. was confirmed by tracing the complete life history from eggs to adults in two different locations.”

We don’t know why cicadas emerge in 13- and 17-year intervals, but thanks to some incredible research, we do now understand the eight-year life cycle of the train millipedes.

cover image 002The train millipedes swarming. (Keiko Niijima)

Lead author and government ecologist Keiko Niijima first started conducting observations into these millipedes in 1972, and two main sites were surveyed between one and five times per year for many of the years between then and 2016.

It was quite an operation, and when they got to the two sites at Mt. Yatsu and Yanagisawa, the job wasn’t exactly easy and quick either.

 

“The soil to a depth of 0–5 cm was dug out, spread on a polyethylene sheet and the millipedes on the sheet were collected using forceps or an aspirator,” the researchers explain.

“Then, the same procedure was repeated for 5–10, 10–15 and 15–20 cm depths.”

Collecting any millipedes they found, they discovered that the millipedes have seven stages (called instars) of growing up, all of which stay in the soil and hibernate during winter and then molt in the summer.

“The train millipedes undertake a molting in the summer every year and have seven larval instars,” the researchers write.

“They become adults by the eighth molting after eight years from egg deposition.”

millipede train swarm image 1 (K. Niijima)

Then, the adults swarm on the surface in September and October, sometimes travelling up to 50 metres to get frisky before hibernating during the winter, and copulate again in late spring.

By August, the females have laid 400 to 1,000 eggs and the adults have all died – ready for another eight-year generation.

As with cicadas, the millipede’s eight years aren’t all in sync everywhere. 

In fact, the team suspects there are seven broods across the mountainous region of Central Japan that completed their lifecycle each in different years. That being said though, they don’t move much, so a particular train line will continue to have the same issue every eight to 16 years from one brood. 

 

Looking at historical records dating all the way back to the 1910s, the researchers were able to attribute nearly every reported millipede swarming to one of the seven broods.

“We have shown the existence of a periodical millipede, a new addition to periodical organisms with long life cycles: periodical cicadas, bamboos and some plants in the genus Strobilanthes,” the team writes.

Parafontaria laminata armigera is the first record of periodical non-insect arthropod.”

With arthropods and insects making up a huge percentage of all animals on Earth, and only a fifth having been identified or named, there’s likely to be plenty more long periodic life cycles out there.

All we’ve got to do is find them.

The research has been published in Royal Society Open Science.

 



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Astronomers Have Identified Another Important Aspect of Planets That Could Host Life

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We are, by now, pretty familiar with the concept of the Goldilocks zone. Also known as the habitable zone, it’s the distance from a star at which liquid water can be present on the surface on a planet – not so hot as to be vaporised, nor so cold as to be frozen.

 

These conditions matter because we count liquid water as a vital ingredient for life. But it’s not the only criterion that can help us to assess a planet’s potential habitability; according to new research based on decades of data, there are also Goldilocks stars.

Not all stars, you see, are built alike. Some are extremely hot and bright – such as the very young, blazing blue OB stars. Some are quite low in temperature, like red M-type dwarfs. These could perhaps be a good temperature, but the Goldilocks zone would be very close to the star, and red dwarfs tend to be turbulent, lashing their surrounding space with violent flares.

Our Sun sits between these two extremes, what is known as a yellow dwarf – a G-type main-sequence star. But, although we know life has emerged in the Solar System (we are, after all, living it), not even the Sun is a Goldilocks star.

Nope. According to astronomers at Villanova University, the best stars for life are one step along the Hertzsprung-Russell chart of star types – that is, K-type stars, which are orange stars a little cooler than the Sun, and a little warmer than a red dwarf.

 

“K-dwarf stars are in the ‘sweet spot,’ with properties intermediate between the rarer, more luminous, but shorter-lived solar-type stars (G stars) and the more numerous red dwarf stars (M stars),” explained Villanova astronomer and astrophysicist Edward Guinan.

“The K stars, especially the warmer ones, have the best of all worlds. If you are looking for planets with habitability, the abundance of K stars pump up your chances of finding life.”

Together with a colleague, astronomer Scott Engle of Villanova University, they presented their research at the 235th meeting of the American Astronomical Society back in January 2020.

Let’s be clear here: astronomers are not looking for habitable planets to find a back-up Earth. Even if we did find Earth 2.0, we just don’t have the technology to get us there.

Our quest for Goldilocks planets has more to do with finding out if there is other life out there in the Universe – and, one step further, if there is intelligent life. Is life normal, or is Earth a giant freak? Narrowing down where life is likely to spring up can help us in that search.

 

Guinan, Engle and others have been monitoring a number of stars F to G-type stars in ultraviolet and X-rays over the last 30 years as part of their Sun in Time program, and M-type red dwarfs for 10 years for the Living with a Red Dwarf program.

Both these programs have been helping to assess the impact of X-ray and ultraviolet radiation of the stars in question on the potential habitability of their planets.

Recently, they expanded their research to include similar data collection on K-type stars – what they have called Living with Goldilocks K-dwarfs. And, indeed, these stars do seem to be the most promising for life-supporting conditions.

goldilocks stars(NASA/ESA/Z. Levy/STScI)

Although the habitable zone of K-type stars is smaller, they are much more common than G-type stars, with around 1,000 of them within just 100 light-years of the Solar System. And they have much longer main-sequence lifetimes.

The Sun is around 4.6 billion years old, with a main-sequence lifetime of around 10 billion years. Complex life only emerged on Earth around 500 million years ago, and scientists think that, in another billion years, the planet will become uninhabitable as the Sun begins to expand, pushing the Solar System’s habitable zone outwards.

 

Red dwarfs are more common, but they’re feisty, subjecting the space around them to intense radiation and flare activity that could strip any close planets of their atmospheres and liquid water.

By contrast, K-type stars have lifetimes between 25 and 80 billion years, offering a much bigger window in which life can emerge than G-type stars; according to the team’s data, they are much calmer than red dwarfs, too.

And there are already K-type stars around which planets have been located – namely Kepler-442, Tau Ceti and Epsilon Eridani

“Kepler-442 is noteworthy in that this star (spectral classification, K5) hosts what is considered one of the best Goldilocks planets, Kepler-442b, a rocky planet that is a little more than twice Earth’s mass,” Guinan said

“So the Kepler-442 system is a Goldilocks planet hosted by a Goldilocks star!”

The search for life could, of course, be much more complicated even than this – for example, if the planet has a highly elliptical orbit, it could produce temperature extremes that would render an otherwise Goldilocks planet uninhabitable.

The location of other planets in the system could make a difference too; and there’s a possibility that the entire galaxy has its own habitable zone (if it does, we know we’re in it, so looking nearby is a good start).

But this research could represent a piece of the puzzle that could make the life needle in the space haystack just a little bit easier to find.

The research was presented at the 235th meeting of the American Astronomical Society in Hawaii.

A version of this article was first published in January 2020.

 



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Astronomers Detect The Most Distant Quasar to Date, Over 13 Billion Light-Years Away

in Science News by


A galaxy billions of light-years away is the most distant of its kind we’ve found to date, embodying yet another challenge to our models of black hole and galaxy formation, and offering a rare glimpse into the early Universe.

 

It’s named J0313-1806, a quasar over 13 billion light-years from Earth, fully formed with a bafflingly huge supermassive black hole at its centre, and churning out newborn stars at a furious rate – just 670 million years after the Big Bang.

A team of researchers led by the University of Arizona even found evidence of a hot quasar wind, blowing from the supermassive black hole at the centre of J0313-1806 at 20 percent of the speed of light.

“This is the earliest evidence of how a supermassive black hole is affecting its host galaxy around it,” said astronomer Feige Wang of UArizona’s Steward Observatory. “From observations of less distant galaxies, we know that this has to happen, but we have never seen it happening so early in the universe.”

Quasars – a shortening of “quasi-stellar radio sources” – are the incredibly bright result of an active galactic nucleus, with a supermassive black hole accreting material at such a rate that the heat generated blazes across the Universe. J0313-1806’s core is accreting material at a rate of 25 solar masses a year; but it’s so far away that only the combined might of some of our most powerful telescopes were able to detect it as an infrared dot at the dawn of time.

 

Then, the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile was used to study it in closer detail. Together, these observations reveal the most distant quasar yet, beating the previous record holder, J1342+0928, by 20 million years.

J1342+0928, identified at 690 million years after the Big Bang, was challenging enough, with a supermassive black hole clocking in at a tremendous 800 million solar masses. But J0313-1806 has it beat hand over fist – its supermassive black hole is twice as massive, at 1.6 billion solar masses.

That’s extraordinarily massive so soon after the Big Bang – and too massive for some of our current models. One of the models proposes that supermassive black holes start small and grow by accreting matter. Another proposes that they form via the direct collapse of dense clusters of stars.

These models can work for other quasars found in the distant Universe, such as J1342+0928, but not for J0313-1806. Even if the J0313-1806 supermassive black hole formed around 100 million years after the Big Bang, and grew as fast as modelling allows, it would still need to have started at 10,000 solar masses right from the outset, the team calculated.

 

There is, however, a third option.

“This tells you that no matter what you do, the seed of this black hole must have formed by a different mechanism,” said astronomer Xiaohui Fan of the UArizona Department of Astronomy. “In this case, one that involves vast quantities of primordial, cold hydrogen gas directly collapsing into a seed black hole.”

There are other reasons J0313-1806 is a fascinating object. There’s its star formation rate, around 200 solar masses a year, classifying it as what we call a starburst galaxy. This is an intense stage in a galaxy’s life; at such high rates of star formation, it’s only a matter of time before all the star-forming material runs out.

And that quasar wind – extreme hot plasma outflows from the accretion disc of material swirling around the supermassive black hole – isn’t helping matters. These winds are stripping the cold star-forming gas from the galaxy, which is thought to eventually extinguish, or quench, star formation.

“We think those supermassive black holes were the reason why many of the big galaxies stopped forming stars at some point,” Fan said.

“We observe this ‘quenching’ at lower redshifts, but until now, we didn’t know how early this process began in the history of the Universe. This quasar is the earliest evidence that quenching may have been happening at very early times.”

Eventually, there will be nothing left nearby for the supermassive black hole to devour, either, and its brilliant blaze will dim, at least from our point of view. Since the light reaching us from J0313-1806 is 13.03 billion years old, the galaxy probably looks very different now from what we are seeing.

Nevertheless, the quasar, and others like it, constitute a growing catalogue that is helping astronomers piece together the mysteries of how our Universe flared to life. And, as our instruments continue to grow more sensitive, so too will our understanding of the beginning of everything continue to grow.

“Future observations,” Wang said, “could make it possible to resolve the quasar in more detail, show the structure of its outflow and how far the wind extends into its galaxy, and that would give us a much better idea of its evolutionary stage.”

The research has been presented at the 237th meeting of the American Astronomical Society. It has also been accepted by The Astrophysical Journal Letters, and is available on arXiv.

 



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