Today's Image of the Day from <a href="https://earthobservatory.nasa.gov/">NASA Earth Observatory</a> features the island of Hainan, China’s southernmost province, in the South China Sea.



According to NASA, the photograph focuses on the landscape around Gangmen Harbor and captures many typical characteristics of Hainan: forested mountain terrain juxtaposed with dense populations.&nbsp;



With tropical beaches along its shoreline, the island spans approximately 1,300 square miles. Floating fishing villages can be found in the shallow waters of the inner bays.



China is a leading country when it comes to wild catch, and also produces about 60 percent of the world’s farmed fish such as carp and tilapia. Aquaculture sites are often paired with fishing ports for sufficient transport.



The photograph was captured by an astronaut onboard the International Space Station (ISS),&nbsp;



Image Credit: NASA Earth Observatory



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By <a href="http://csexton@earth.com">Chrissy Sexton</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer

The island of Hainan in the South China Sea

Today's Image of the Day from NASA Earth Observatory features...

Because David was frightened of the bear's erratic behavior, he humanely put down the creature. He brought the bear, who still mystified him, to a local government officer who was just as puzzled. Photo Credit: brytta / Getty Images

Erratic Behavior

Because David was frightened of the bear's erratic behavior, he...

But the officer had a hunch as to what this bear-thing was. He figured it was some sort of hybrid, but to find out for sure, the officer sent the bear's DNA to a lab to be tested. They anxiously waited on the DNA results, but this was no episode of Maury. Photo Credit: ernestoeslava/Pixabay

DNA Testing

But the officer had a hunch as to what this...

The tests showed that years prior to David's discovery, 20 of these animals were born in captivity. But because these particular hybrid animals and their parents had been kept apart from the wild, where did David's blonde bear originate from? Photo Credit: Handout / Handout / Getty Images

Born In Captivity

The tests showed that years prior to David's discovery, 20...

Well, in 2006, a hunter found the first documented hybrid bear on Banks Island, Northern Territories, Canada, which is a bit northwest of where David found his hybrid in 2010. While those bears were never found to be particularly exciting or noteworthy to scientists, things changed in 2016. ArtTower/Pixabay

Emerging Hybrids

Well, in 2006, a hunter found the first documented hybrid...

In 2016, a hunter discovered the third wild hybrid bear of its kind in Arviat, Canada. By this point, scientists had hypothesized that pesky climate change was the culprit behind bear interbreeding, as warming climates caused the Arctic ice to melt, which ain't good for the polar bears. Photo Credit: blende12/Pixabay

Changing Climates

In 2016, a hunter discovered the third wild hybrid bear...

As anyone old enough to have witnessed the monumental event will be able to remember, Aldrin, Armstrong and Mike Collins were launched into space in July 1969. The trio departed Earth from the Kennedy Space Center in Florida in a Saturn V rocket. As Aldrin recalled at a 50th anniversary gala, the initial journey was also a surprisingly smooth one. Photo Credit: Project Apollo Archive/Flickr

Apollo 11 liftoff - July 16, 1969

There has been much debate and hypothesizing about the origins of <a href="https://www.earth.com/news/domestication-shrunk-rabbits-brains/">domestication</a> in horses (Equus caballus). Where were they first domesticated, and by whom? How did they spread around the globe and what were their ancestors like? Many previous studies have attempted to answer these questions but no final resolution has been forthcoming, and the early domestication of the horse has remained exceedingly difficult to trace in the archeological record.&nbsp;



In a new study led by Professor Ludovic Orlando of <a href="https://www.cnrs.fr/">CNRS</a>, a team of 162 international scientists has had a breakthrough. The experts, who specialize in archeology, paleogenetics and linguistics used the modern technologies of genetic analysis.&nbsp;



In recent years, a scientific consensus had emerged linking the Botai culture of northern Kazakhstan with the first domestication of horses, based on the presence of 5,500-year-old skeletal remains with damage to the dentition that is commonly linked to the use of bridle mouthpieces. However, when Ludovic Orlando's team looked at the DNA from the archeological remains, they found that the animals were Przewalsky’s horses (Equus przewalski), a totally different species from modern domesticated horses.&nbsp;



In all other locations hypothesized to be potential foci for domestication, for example Anatolia, Siberia and the Iberian Peninsula, the evidence turned out to be false. “We knew that the time period between 4,000 to 6,000 years ago was critical but no smoking guns could ever be found,” said Professor Orlando.&nbsp;



The scientific team thus decided to extend their study and analyze the genomes of 273 horses that lived between 50,000 and 200 years BC, at sites throughout Eurasia. This information was sequenced at the Centre for Anthropobiology and Genomics of Toulouse (CNRS/Université Toulouse III – Paul Sabatier) and Genoscope&nbsp;(CNRS/CEA/Université d’Évry) before being compared with the genomes of modern domestic horses.



The results indicated that, although Eurasia was once populated by genetically distinct horse populations, a dramatic change occurred between 2000 and 2200 BC. “That was a chance: the horses living in Anatolia, Europe, Central Asia and Siberia used to be genetically quite distinct,” notes Dr Pablo Librado, first author of the study.&nbsp;



Then, a single genetic profile, previously found only on the Pontic steppes (North Caucasus), began to spread beyond its native region, replacing all the wild horse populations from the Atlantic to Mongolia. From this the authors conclude that horses were first domesticated in the Pontic-Caspian steppes,&nbsp;northern Caucasus, before spreading out through the rest of Eurasia within a few centuries.&nbsp;



“The genetic data also point to an explosive demography at the time, with no equivalent in the last 100,000 years,” adds Professor Orlando. “This is when we took control over the reproduction of the animal and produced them in astronomic numbers.”



Two striking differences were found in the genome of this horse that spread so rapidly throughout Eurasia: the new horses had more docile behavior and stronger backbones than the breeds they replaced. The researchers suggest that these characteristics ensured the animals’ success at a time when horse travel was becoming more commonplace and widespread.



Indeed, the research also showed that the genetically different horse spread throughout Asia at the same time as spoke-wheeled chariots and Indo-Iranian languages. However, the migrations of Indo-European populations, from the steppes to Europe during the third millennium BC&nbsp;could not have been based on the horse, as its domestication and diffusion came later. This demonstrates the importance of incorporating the history of animals when studying human migrations and encounters between cultures, state the authors.



The study is published in the journal <a href="https://www.nature.com/">Nature</a>.



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By <a href="mailto:bosman@truewan.co.za">Alison Bosman</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer

The origin of horse domestication has finally been revealed

There has been much debate and hypothesizing about the origins...

Until recently, it was thought that Christopher Columbus was the first European to reach the Americas in 1492. However, a new study led by the <a href="https://www.rug.nl/?lang=en">University of Groningen</a> has found that the <a href="https://www.earth.com/news/the-vikings-had-the-worlds-deadliest-virus-1400-years-ago/">Vikings</a> got there centuries beforehand, and were already active in Newfoundland, Canada, in 1021 AD.&nbsp;



The Vikings sailed great distances in their longships, and established settlements in Iceland, Greenland, and L’Anse aux Meadows in Newfoundland, Canada. Yet, the precise number of Viking expeditions to the Americas, and the duration of their stays over the Atlantic remain unknown.&nbsp;



Previous dates for the Viking presence in the Americas have relied heavily on the Icelandic Sagas that began as oral histories and were written down centuries after the events they describe. Although these Sagas often describe both violent and amiable encounters between the Vikings and indigenous American populations, little archaeological evidence has been uncovered to support such exchanges.



In this new study, published in the journal <a href="https://dx.doi.org/10.1038/s41586-021-03972-8">Nature</a>, the chopping of wood by Vikings at L'Anse aux Meadows was dated to the year 1021 AD. The scientists studied three pieces of wood from three different trees that displayed clear evidence of cutting and slicing by metal blades coming from contexts attributable to the Vikings. The precise dating of these operations was possible because a massive solar storm occurred in 992 AD which produced a distinct radiocarbon signal in tree rings from the following year.



"The distinct uplift in radiocarbon production that occurred between 992 and 993 AD has been detected in tree-ring archives from all over the world" explained study senior author Michael Dee, an associate professor in the <a href="https://www.rug.nl/research/esrig/?lang=en">Energy and Sustainability Research Institute</a> at the University of Groningen. "Finding the signal from the solar storm 29 growth rings in from the bark allowed us to conclude that the cutting activity took place in the year 1021 AD," added&nbsp;study lead author&nbsp;Margot Kuitems, a postdoctoral researcher in the same institute.



This date also marks the earliest known time at which the Atlantic had been crossed, and human migration had finally encircled the entire planet.



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By <a href="mailto:andrei.ionescu5891@gmail.com">Andrei Ionescu</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer

The Vikings reached America long before Columbus

Until recently, it was thought that Christopher Columbus was the...

According to a new study led by the <a href="https://medicine.wustl.edu/">Washington University School of Medicine</a> in St. Louis, like many other things in life, <a href="https://www.earth.com/news/poor-sleep-quality-is-associated-with-mental-illness/">sleep</a> is best in moderation. Through a longitudinal study of older adults, scientists have discovered that both short and long sleepers experience greater cognitive decline than people who sleep moderately.



Both poor sleep and Alzheimer’s disease are associated with cognitive decline. Thus, separating the effects of each has proven challenging. By tracking the cognitive functioning of a group of 100 older adults over 4.5 years and analyzing it against levels of proteins related to Alzheimer’s disease and measures of brain activity during sleep, the scientists have shed new light on the complex relationship among sleep, Alzheimer’s disease, and cognitive functioning.



“It’s been challenging to determine how sleep and different stages of Alzheimer’s disease are related, but that’s what you need to know to start designing interventions,” said study lead author&nbsp;Brendan Lucey, an associate professor of Neurology and director of the Washington University&nbsp;<a href="https://u7061146.ct.sendgrid.net/ls/click?upn=4tNED-2FM8iDZJQyQ53jATUUOrhW-2FAaQ3u4vk6vdUg1mvTrnTAtBrEOmwAeYJBqRi6y3qh_qUUMznMkXGT9vocK663RhihR1E3P7Zhw8trthuwelyTfR-2BnsLMSwOQIMF0GjbacMCc3OzgSGJNEF-2B2N6cD3eKEvG2HlsfjpnB1jpUBbe5O9IlB7tEy56cOGuT7q19fXHNsbMCsrKAnW7J6nRb05tLvZC1X2ytS4TQ3xmyJue3XmP0s4HzBllG-2FqaWXesoRM6RrO1MD3zQxgVImnnArPYAwIzZvy9uY2ikay6upHyAtl5B7R-2F7RPsI6xaZ4oIovH3NO5pgoKIeQYgduhqHTfI-2FecROPms0BXQs-2BQZm7mxUsE2p3cp2UYbmouhwpeG-2FRONxuQMbWrfWGStUkrHtzXj4ULF1cgUR52VM9Fcl-2BOBagQ-3D">Sleep Medicine Center</a>.&nbsp;



The researchers found that cognitive scores declined for the persons who slept either less than 4.5 hours or more than 6.5 hours per night, while scores remained stable for those in the middle of the range. While previous studies argued that short amounts of sleep lead to mental health issues, these new findings show that too much sleep can also be harmful. This suggests that sleep quality could be more important than quantity. Moreover, sleep problems appears to accelerate the brain damage caused by Alzheimer’s.



“Our study suggests that there is a middle range, or ‘sweet spot,’ for total sleep time where cognitive performance was stable over time. Short and long sleep times were associated with worse cognitive performance, perhaps due to insufficient sleep or poor sleep quality,” explained Professor Lucey.



“An unanswered question is if we can intervene to improve sleep, such as increasing sleep time for short sleepers by an hour or so, would that have a positive effect on their cognitive performance so they no longer decline? We need more longitudinal data to answer this question.”



However, according to Lucey, each person’s sleep needs are unique and people who wake up rested on either short or long sleeping schedules should not feel compelled to change their habits.



The study is published in the journal <a href="https://academic.oup.com/brain">Brain</a>.



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By <a href="mailto:andrei.ionescu5891@gmail.com">Andrei Ionescu</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer

Moderate sleep reduces the risk of cognitive decline

According to a new study led by the Washington University...

Mammoths, the woolly cousins of today’s <a href="https://www.earth.com/news/elephants-can-be-very-cooperative-until-the-food-gets-scarce/">elephants</a>, roamed the Earth for over five million years before they mysteriously vanished about 4,000 years ago. A new study led by the <a href="https://www.cam.ac.uk/">University of Cambridge</a> has found that the cause of their extinction was not humans, as previously thought, but climate change.



Mammoths lived alongside early humans and were regularly hunted by hominids for food and clothing. Moreover, the animals’ skeletons were used to build shelters and various tools and instruments, ranging from harpoons to flutes.



“Scientists have argued for 100 years about why mammoths went extinct. Humans have been blamed because the animals had survived for millions of years without climate change killing them off before, but when they lived alongside humans they didn’t last long and we were accused of hunting them to death,” said study leader Eske Willerslev, a fellow at the University of Cambridge’s St. John’s College. However, humans in fact lived over 2,000 years alongside mammoths, without causing their extinction.



By analyzing ancient DNA samples from plants and animal remains collected over a period of 20 years from sites in the Arctic where mammoths used to live, Professor Willerslev and his colleagues have found that, after the last Ice Age from late Pleistocene, the climate got wetter and the ice began to melt, leading to the formation of rivers, lakes, and marshes. These changes in the ecosystems significantly reduced the vegetation on which mammoths relied, including various types of grass, small shrubs, plants, and flowers, and made it impossible for them to survive.



“We have finally been able to prove was that it was not just the climate changing that was the problem, but the speed of it that was the final nail in the coffin – they were not able to adapt quickly enough when the landscape dramatically transformed and their food became scarce,” explained Professor Willerslev.



“This is a stark lesson from history and shows how unpredictable climate change is – once something is lost, there is no going back. Precipitation was the cause of the extinction of woolly mammoths through the changes to plants. The change happened so quickly that they could not adapt and evolve to survive,” he concluded.



The study is published in the journal <a href="https://www.nature.com/">Nature</a>.



Image Credit: Daniel Eskridge



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By <a href="mailto:andrei.ionescu5891@gmail.com">Andrei Ionescu</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer

Mammoths were wiped out by climate change, not humans

Mammoths, the woolly cousins of today’s elephants, roamed the Earth...

A new study published in the <a href="https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2021JC017563">Journal of Geophysical Research: Oceans</a> has found that patterns of Arctic warming and sea ice loss can be determined by tracking the path of frozen trees as they made their way across the Arctic Ocean over the past 500 years. 



By dating and tracking pieces of driftwood found on beaches in Svalbard, a Norwegian archipelago from the Arctic circle, scientists managed to determine where these trees floated and to reconstruct the levels of sea ice over time. The experts could also derive the patterns of currents that propelled the driftwood.



The Arctic Ocean collects trees that fall into high-latitude rivers from North America and Eurasia. When the temperatures were very low, some of these trees were frozen in the sea ice, which floated across the ocean until reaching Svalbard’s shores.



In the summers of 2016 and 2018, an international team of scientists gathered driftwood from several beaches in northern Svalbard, and analyzed them in the laboratory. The tree ring patterns of each driftwood piece were compared to a database of measured rings of trees from the boreal forests. This procedure helped scientists trace trees to specific countries, watersheds, or even rivers and determine how driftwood sources varied over time.



“This is the first time driftwood has been used to look at large-scale changes in Arctic sea ice dynamics and circulation patterns,” said study lead author Georgia Hole, a geoscientist at the <a href="https://www.ox.ac.uk/">University of Oxford</a>.



By pairing driftwood data with early sea ice observations from 1600 to 1850, as well as more recent sea ice data collected from airplane and satellite imagery, the researchers revealed a slow but steady northward migration of the lowest-latitude sea ice, reflecting a gradual ocean warming and loss of sea ice.



“We also saw an increase in variability in the driftwood record from 1700 to 1850, which we interpret as increased variability in sea ice,” said Hole. Since colder climates are correlated with more sea ice, earlier driftwood reflected a wider range of sources. As the ocean warmed up and sea ice melted, less driftwood could make that journey.



Although this technique offers a reliable and nuanced way of understanding past sea ice conditions, if the Arctic continues to warm and will finally lose its ice altogether, such methods of investigation will not be available anymore.



“It’s such a fragile system. If the sea ice does decline as predicted, then this will kind of be a dying field,” Hole concluded.



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By <a href="mailto:andrei.ionescu5891@gmail.com">Andrei Ionescu</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer

Centuries-old record of Arctic warming found in driftwood

A new study published in the Journal of Geophysical Research:...

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are large, complex, man-made chemicals that are widely used in everyday life. For example, they are used to make non-stick surfaces in cookware, to prevent stains from seeping into carpets, upholstery and clothes, and to make effective foam for fighting <a href="https://www.earth.com/news/wildfires-in-the-west-linked-to-smoke-related-deaths-in-the-east/">fires</a>. The chemicals are also used in the aerospace, automotive, construction, and electronics industries, as well as in the military.



There are more than 4,700 different types of PFAS, all made of molecules that consist of a basic chain of linked carbon and fluorine atoms. Because the chemical bond between a carbon and a fluorine atom is one of the strongest in the chemical world, these molecules do not degrade in the environment. In fact, as a group they have been termed “forever chemicals” and have been identified widely in the environment as well as in the blood and urine of people and domestic animals. They have also been shown to accumulate in humans and to be associated with a diverse array of negative health consequences.



Research published today in the American Chemical Society’s journal&nbsp;<a href="https://pubs.acs.org/journal/esthag">Environmental Science &amp; Technology</a>&nbsp;assessed the levels of PFAS in organic waste products used to fertilize agricultural fields in France. Products such as livestock manures, urban sewage sludges, composts, and industrial wastes are applied to French agricultural lands, and Sébastien Sauvé, along with colleagues from France’s National Research Institute for Agriculture, Food and Environment, wanted to assess the occurrence and concentrations of multiple classes of PFAS in the organic fertilizer products used currently, as well as in those used in the past.



The researchers selected 47 samples of organic waste products intended for field application, collected in France between 1976 and 2018. They used high-resolution mass spectrometry to analyze the samples for known PFAS, as well as for other, previously uncharacterized forever chemicals.&nbsp;



Over 90 percent of the samples contained at least one PFAS, with a maximum of 113 different perfluoroalkyl and polyfluoroalkyl compounds detected in a single sample.&nbsp;The greatest presence of PFAS was found in samples of urban origin – there were fewer and lower levels of PFAS in livestock manures than in wastes of urban origin.&nbsp;



The toxic and potentially harmful effects of forever chemicals have been recognized for decades, and the manufacture and use of certain of these chemicals has been banned or phased out in several countries. However, new formulations are continually being developed, to replace the banned ones, and the long-term environmental and health effects of these variants are not known.



The researchers were concerned that, after humans and livestock ingest PFAS, their excrement could contain these compounds which, when applied to agricultural fields as fertilizer, have the potential to leach into the groundwater and bio-accumulate in food crops. The persistent chemicals have already been recorded in the soil, air and water in many locations in the world.



The results of the research also showed that the presence of older classes of PFAS was more common in the historical samples. These PFAS have been phased out slowly in France and this explains their absence in the more contemporary samples of organic fertilizer. However, the more recent samples contained a variety of newer classes of PFAS, as well as compounds called fluorotelomers, which could degrade to form more persistent PFAS in the environment.&nbsp;



The unregulated development and use of PFAS has led to the current situation where thousands of different PFAS chemicals exist and are used in many different consumer, commercial, and industrial products. These forever chemicals are clearly already prevalent in our soil, water and air, and their potential human health and environmental risks are largely unquantified.



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By <a href="mailto:bosman@truewan.co.za">Alison Bosman</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer

Urban waste has more "forever chemicals" than livestock manure

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are large, complex, man-made chemicals...

A new study published in the journal <a href="https://academic.oup.com/advances">Advances in Nutrition</a> looks at the <a href="https://www.earth.com/news/the-pandemic-has-had-an-enormous-impact-on-public-health-services/">health</a> benefits of orange juice. The research, funded by the Florida Department of Citrus (FDOC), suggests that orange juice helps adults fight inflammation and oxidative stress. 



“We know that 100% orange juice contains a number of nutrients, like vitamin C, as well as beneficial bioactive compounds that have the potential to reduce inflammation and oxidative stress," said Gail Rampersaud, a registered dietician with the FDOC.



"This review tells us that some studies find benefits with 100% orange juice, but we need more data and large well-designed studies to make more definitive conclusions. This analysis is especially helpful as we and others plan future research related to orange juice.”



The experts reviewed previous research into the health benefits of orange juice, which revealed that citrus juice reduces interleukin-6, a known measure of inflammation. Overall, the researchers analyzed data from 21 studies covering 307 healthy adults and 327 adults at risk of disease.&nbsp;



Ultimately, the review showed that orange juice consumption either had no effect or positive effects on inflammation or oxidative stress. These results compare favorably with an earlier review funded by the FDOC which found that hesperidin, a naturally occurring compound in oranges and orange juice, helps reduce inflammation.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;



The researchers caution that further research is needed, as their study was focused on a small number of participants, has a low amount of evidence, and some bias involved.&nbsp;



"While much of the naturally occurring fiber and vitamin C are lost during processing, 100% fruit juices show similar vitamin and mineral content as equal quantities of whole fruit. Importantly, these juices retain much of the antioxidant nutrients and phytochemicals of the whole fruit, which can reduce both inflammation and chronic disease risk and support human health," wrote the researchers



The study was carried out by Tufts University, George Mason University and Think Healthy Group.&nbsp;



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By <a href="mailto:zachfitzner@yahoo.com">Zach Fitzner</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer

Orange juice can reduce inflammation and chronic disease

A new study published in the journal Advances in Nutrition...

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Today's Video of the Day from the <a href="https://www.esa.int/">European Space Agency</a> features the North Frisian Islands, also known as the Wadden Islands, located just off the coast of northern Europe.



The Frisian Islands stretch from the northwest of the Netherlands through Germany to the west of Denmark. The archipelago is divided into three regions - the East, West, and North Frisian Islands.



The low-lying islands form a unique zone between the mainland and the North Sea known as the Wadden Sea that is the largest unbroken system of intertidal sand and mud flats in the world.



The Wadden Sea is a UNESCO world heritage site, and is considered one of the most important areas for migratory birds in the world. The biodiverse region is also home to thousands of other plant and animal species.&nbsp;



The North Frisian Islands include Sylt, Föhr, Amrum, and Pellworm. The largest of the islands is Sylt in Northern Germany, which is well known for the distinctive shape of its shoreline. The island extends more than 35 kilometers in length - yet in some places, is only one kilometer wide.&nbsp;



The image was captured on June 1, 2020 by the Copernicus Sentinel-2 mission.



Video Credit: ESA&nbsp;



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By <a href="http://csexton@earth.com">Chrissy Sexton</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer

The North Frisian Islands

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Today's Video of the Day from the <a href="https://www.acs.org/">American Chemical Society</a> describes how seismic waves were used to locate trillions of tons of diamonds deep below Earth's surface.



Scientists at MIT estimate that a quadrillion tons of diamonds are located about 100 miles deep in the Earth. This figure, which is one thousand times more than one trillion, is mind boggling.



Seismic waves move through various materials at different speeds, depending on how rigid the material is.&nbsp;



Using sound waves to make measurements, the MIT team discovered that seismic waves were moving much faster at about 90 to 150 miles below the Earth's surface.



The experts matched the speed of the sound waves to the density of diamonds. Compared to other rocks, sound travels through diamonds twice as fast.



Video Credit: ACS&nbsp;



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By <a href="http://csexton@earth.com">Chrissy Sexton</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer

A quadrillion tons of diamonds are beneath Earth's surface

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Maharloo Lake in southwest Iran Today's Video of the Day from the <a href="https://www.esa.int/">European Space Agency</a> features a satellite view of Maharloo Lake, a seasonal salt lake in southwest Iran.



According to ESA, yearly evaporation in this desert region southeast of Shiraz is much greater than the yearly rainfall, meaning that Maharloo Lake is often very dry.



Such a high evaporation rate has gradually left the lake bed covered by salt. The increased salinity promotes a variety of organisms that display colors ranging from pink to orange to red, with the strength of the color differing in various periods of the year, explains ESA.



The image was captured by the Copernicus Sentinel-2 mission.



Video Credit: ESA&nbsp;



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By <a href="http://csexton@earth.com">Chrissy Sexton</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer

Maharloo Lake in southwest Iran

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Today's Video of the Day from the <a href="https://www.esa.int/">European Space Agency</a> features a satellite view of the Mackenzie River, a major river system in the Canadian boreal forest.&nbsp;



The Mackenzie's drainage basin is the second largest of any river in North America. The river delta stretches over 12,000 square kilometers, or 7,456 miles, and measures more than 190 kilometers from north to south.&nbsp;&nbsp;



The Mackenzie River covers a vast, thinly populated region of forest and tundra across the Northwest Territories - flowing from the Great Slave Lake to the Beaufort Sea in the Arctic Ocean.&nbsp;



According to ESA, around 75 percent of the Mackenzie basin sits within a permafrost area. Rising temperatures are causing permafrost to thaw, which releases methane and carbon dioxide into the atmosphere. Thawing permafrost can also cause erosion, flooding, and landslides.



Video Credit: ESA&nbsp;



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By <a href="http://csexton@earth.com">Chrissy Sexton</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer

The Mackenzie River in the Canadian boreal forest

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Today's Video of the Day from the <a href="https://www.esa.int/">European Space Agency</a> (ESA) features New Delhi in the north-central part of India. New Delhi is the country's second largest city. It is located within the enormous metropolitan area of Delhi, India’s capital territory.&nbsp;



According to ESA, Delhi’s urban area consists of the historical city of Old Delhi in the north, New Delhi in the south, and now also includes the nearby cities of Ghaziabad, Faridabad, Gurugram and Noida.&nbsp;



Delhi is bounded by the state of Haryana to the north, west and south. To the east, the city borders the state of Uttar Pradesh.



New Delhi is also located on the banks of one of the country’s most sacred rivers, the Yamuna is a tributary of the Ganges River.



Video Credit: ESA&nbsp;



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By <a href="http://csexton@earth.com">Chrissy Sexton</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer

New Delhi in north-central India

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Today's Video of the Day from the <a href="https://www.esa.int/">European Space Agency</a> features the second largest river delta in Europe, the Danube Delta.&nbsp;



According to ESA, the Danube Delta covers an area of 4,300 square kilometers and is known for its abundance of birdlife, as it hosts more than 300 species of birds as well as 45 species of freshwater fish in its numerous lakes and marshes.&nbsp;



From the Black Forest mountains, the Danube River passes through 10 countries: Germany, Austria, Slovakia, Hungary, Croatia, Serbia, Bulgaria, Romania, Moldova and Ukraine.



Video Credit: ESA&nbsp;



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By <a href="http://csexton@earth.com">Chrissy Sexton</a>, <a href="https://www.earth.com/staff/">Earth.com</a> Staff Writer

Earth from Space: Danube Delta

[sendtonews key="8m64nOximG-1556941-12187" type="single"] Today's Video of the Day from the...

Photo Credit: Win McNamee/Getty Images

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