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Scientists Reveal Secrets of Desert Star Dunes

A view of the Lala Lallia star dune of the Sahara Desert, in Erg Chebbi, Morocco, as seen in an undated handout image from 2008 and obtained by Reuters on March 1, 2024. Charlie Bristow/Handout via REUTERS
A view of the Lala Lallia star dune of the Sahara Desert, in Erg Chebbi, Morocco, as seen in an undated handout image from 2008 and obtained by Reuters on March 1, 2024. Charlie Bristow/Handout via REUTERS
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Scientists Reveal Secrets of Desert Star Dunes

A view of the Lala Lallia star dune of the Sahara Desert, in Erg Chebbi, Morocco, as seen in an undated handout image from 2008 and obtained by Reuters on March 1, 2024. Charlie Bristow/Handout via REUTERS
A view of the Lala Lallia star dune of the Sahara Desert, in Erg Chebbi, Morocco, as seen in an undated handout image from 2008 and obtained by Reuters on March 1, 2024. Charlie Bristow/Handout via REUTERS

They are among the wonders of our deserts: star dunes, the vaguely pyramid-shaped sand formations up to about 1,000 feet (300 meters) tall with arms stretching out from a central peak to give them a star-like appearance when viewed from above.
Scientists on Monday unveiled the first in-depth study of a star dune, revealing the internal structure of these geological features and showing how long it took for one of them to form - more quickly than expected but still a process unfolding over many centuries.
The study focused upon a star dune in eastern Morocco called Lala Lallia, meaning "highest sacred point" in the local Berber language, situated within the Sahara Desert in a small sand sea called Erg Chebbi about 3 miles (5 km) from the town of Merzouga, close to the border with Algeria.
Lala Lallia rises about 330 feet (100 meters) above the surrounding dunes and is approximately 2,300 feet (700 meters) wide, containing about 5-1/2 million metric tons of sand.
According to Reuters, he researchers used ground-penetrating radar to peer inside the dune and employed luminescence dating to determine how long Lala Lallia has taken to form, a method based on the amount of energy trapped inside the grains of sand. The answer: about 900 years, accumulating roughly 6,400 metric tons annually as wind relentlessly blows sand through the desert.
Star dunes make up just under 10% of the dunes in Earth's deserts and are the tallest ones, surpassing other types such as crescent-shaped barchan dunes and straight and lengthy linear dunes. They also have been spotted on Mars and on Saturn's large moon Titan.
"I first encountered star dunes in Namibia 20 years ago, and was instantly amazed at the size of them. I have a vivid memory of the long climb to the top, struggling up very loose sand in the heat of the day," said geographer Geoff Duller of Aberystwyth University in Wales, co-author of the study published in the journal Scientific Reports.
"I find desert dunes very beautiful," Duller added. "The sight of the sinuous curves, and the way that the light and shadow changes with the sun mean that they always look different, whether that is in the cool of the morning, the midday sun or near sunset. The different colors of sand in different deserts are also very striking, with yellow, white, red and even black dunes in different parts of the world."
The ground-penetrating radar revealed the layers within the Lala Lallia dune, showing how it was constructed over time through accumulating sand and how parts of its internal structure resembled other types of dunes.
"Star dunes are formed in areas with complex wind regimes, which means winds blowing from different directions, and net sand accumulation, points within the desert where big piles of sand can be blown around to form giant dunes," said Birkbeck University of London sedimentologist and study co-author Charlie Bristow.
The researchers also determined that Lala Lallia is moving westerly at a speed of about 1.6 feet (0.5 meters) annually.
While many star dunes are known today, only a single ancient one has been found preserved as sandstone in the geological record, dating to about 250 million years ago, in Scotland. By revealing their internal structure, the researchers said their findings provide a guide for geologists to identify more sandstone remnants of ancient star dunes.
Earth's largest star dunes are found in the Badain Jaran desert in western China. Star dunes also are found in places including the Namib Sand Sea in Namibia, large sand seas in Algeria such as the Grand Erg Oriental and Grand Erg Occidental, and Rub' al Khali in Saudi Arabia. In North America, Great Sand Dunes National Park in Colorado contains a series of them.
"They form extraordinary and awe-inspiring landscapes," Bristow said. "From the ground they can be intimidating, mobile mountains of sand."

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Rocket Re-entry Pollution Measured in Atmosphere for 1st Time

A SpaceX Falcon 9 rocket with the company's Dragon spacecraft on top launches from Space Launch Complex 40 for the Crew-12 mission at Cape Canaveral Space Force Station in Florida on February 13, 2026. (Photo by Jim WATSON / AFP)
A SpaceX Falcon 9 rocket with the company's Dragon spacecraft on top launches from Space Launch Complex 40 for the Crew-12 mission at Cape Canaveral Space Force Station in Florida on February 13, 2026. (Photo by Jim WATSON / AFP)
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Rocket Re-entry Pollution Measured in Atmosphere for 1st Time

A SpaceX Falcon 9 rocket with the company's Dragon spacecraft on top launches from Space Launch Complex 40 for the Crew-12 mission at Cape Canaveral Space Force Station in Florida on February 13, 2026. (Photo by Jim WATSON / AFP)
A SpaceX Falcon 9 rocket with the company's Dragon spacecraft on top launches from Space Launch Complex 40 for the Crew-12 mission at Cape Canaveral Space Force Station in Florida on February 13, 2026. (Photo by Jim WATSON / AFP)

When part of a SpaceX rocket re-entered Earth's atmosphere exactly a year ago, it created a spectacular fireball that streaked across Europe's skies, delighting stargazers and sending a team of scientists rushing towards their instruments.

The German team managed to measure the pollution the rocket's upper stage emitted in our planet's difficult-to-study upper atmosphere -- the first time this has been achieved, according to a study published on Thursday.

It is vital to learn more about this little-understood form of pollution because of the huge number of satellites that are planned to be launched in the coming years, the scientists emphasized.

In the early hours of February 19, 2025, the upper stage of a Falcon 9 rocket was tumbling back to Earth when it exploded into a fireball that made headlines from the UK to Poland.

"We were excited to try and test our equipment and hopefully measure the debris trail," the team led by Robin Wing and Gerd Baumgarten of the Leibniz Institute of Atmospheric Physics in Germany told AFP via email.

In particular, the scientists wanted to measure how the rocket polluted what they call the "ignorosphere" -- because it is so difficult to study.

This region between 50 to 100 kilometers (31 to 62 miles) above Earth includes the mesosphere and part of the lower thermosphere.

- 'Harbinger' -

The team used technology called LIDAR, which measures pollution in the atmosphere by shooting out lots of laser pulses and seeing which bounce back off something.

They detected a sudden spike in the metal lithium in an area nearly 100 kilometers above Earth. This plume had 10 times more lithium than is normal in this part of the atmosphere.

The team then traced the plume back to where the rocket re-entered the atmosphere, west of Ireland.

For the first time, this proves it is possible to study pollution from re-entering rockets at such heights before it disperses, the scientists said.

But the impact from this rocket pollution remains unknown.

"What we do know is that one ton of emissions at 75 kilometers (altitude) is equivalent to 100,000 tons at the surface," they said.

The study warned the case was a "harbinger" of the pollution to come, given how many rockets will be needed to launch all the satellites that Earth is planning to blast into space.

Currently, there are around 14,000 active satellites orbiting our planet.
In the middle of last month, China applied for permission to launch around 200,000 satellites into orbit.

Then at the end of January, billionaire Elon Musk's SpaceX applied for permission to launch one million more.

Eloise Marais, a professor of atmospheric chemistry at University College London not involved in the new study, told AFP the research was "really important".

"There is currently no suitable regulation targeting pollution input into the upper layers of the atmosphere," she explained.

"Even though these portions of the atmosphere are far from us, they have potentially consequential impacts to life on Earth if the pollutants produced are able to affect Earth's climate and deplete ozone in the layer protecting us from harmful UV radiation."

The study was published in the journal Communications Earth & Environment.

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Deep-sea Fish Break the Mold with Novel Visual System

A close-up showing the shiny silver-green photophores (light organs) on the lower head of the deep-sea fish Maurolicus muelleri from the Red Sea, seen in this photograph released on February 11, 2026. Dr. Wen-Sung Chung/Handout via REUTERS
A close-up showing the shiny silver-green photophores (light organs) on the lower head of the deep-sea fish Maurolicus muelleri from the Red Sea, seen in this photograph released on February 11, 2026. Dr. Wen-Sung Chung/Handout via REUTERS
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Deep-sea Fish Break the Mold with Novel Visual System

A close-up showing the shiny silver-green photophores (light organs) on the lower head of the deep-sea fish Maurolicus muelleri from the Red Sea, seen in this photograph released on February 11, 2026. Dr. Wen-Sung Chung/Handout via REUTERS
A close-up showing the shiny silver-green photophores (light organs) on the lower head of the deep-sea fish Maurolicus muelleri from the Red Sea, seen in this photograph released on February 11, 2026. Dr. Wen-Sung Chung/Handout via REUTERS

For more than a century, biology textbooks have stated that vision among vertebrates - people included - is built from two clearly defined cell types: rods for processing dim light and cones for bright light and color. New research involving deep-sea fish shows this tidy division is, in reality, not so tidy.

Scientists have identified a new type of visual cell in deep-sea fish that blends the shape and form of rods with the molecular machinery and genes of cones. This hybrid type of cell, adapted for sight in gloomy light conditions, was found in larvae of three deep-sea fish species in the Red Sea, Reuters reported.

The species studied were: a hatchetfish, with the scientific name Maurolicus mucronatus; a lightfish, named Vinciguerria mabahiss; and a lanternfish, named Benthosema pterotum. The hatchetfish retained the hybrid cells throughout its life. The other two shifted to the usual rod-cone dichotomy in adulthood.

All three are small, with adults measuring roughly 1-3 inches (3-7 cm) long and the larvae much littler. They inhabit a marine realm of twilight conditions, with sunlight struggling to penetrate into the watery depths.

The vertebrate retina, a sensory membrane at the back of the eye that detects light and converts it into signals to the brain, possesses two main types of light-sensitive visual cells, called photoreceptors. They are named for their shape: rods and cones.

"The rods and cones slowly change position inside the retina when moving between dim and bright conditions, which is why our eyes take time to adjust when we flick on the light switch on our way to the restroom at night," said Lily Fogg, a postdoctoral researcher in marine biology at the University of Helsinki in Finland and lead author of the research published in the journal Science Advances.

"We found that, as larvae, these deep-sea fish mostly use a mix-and-match type of hybrid photoreceptor. These cells look like rods - long, cylindrical and optimized to catch as many light particles - photons - as possible. But they use the molecular machinery of cones, switching on genes usually found only in cones," Fogg said.

The researchers examined the retinas of fish larvae caught at depths from 65 to 650 feet (20 to 200 meters). In the type of dim environment they inhabit, rod and cone cells both are usually engaged in the vertebrate retina, but neither works very well. These fish display an evolutionary remedy.

"Our results challenge the longstanding idea that rods and cones are two fixed, clearly separated cell types. Instead, we show that photoreceptors can blend structural and molecular features in unexpected ways. This suggests that vertebrate visual systems are more flexible and evolutionarily adaptable than previously thought," Fogg said.

"It is a very cool finding that shows that biology does not fit neatly into boxes," said study senior author Fabio Cortesi, a marine biologist and neuroscientist at the University of Queensland in Australia. "I wouldn't be surprised if we find these cells are much more common across all vertebrates, including terrestrial species."

All three species emit bioluminescence using small light-emitting organs on their bodies, mostly located on the belly. They produce blue-green light that blends with the faint background light from the sun above. This strategy, called counterillumination, is a common form of camouflage in the deep sea to avoid predators.

"Small fish like these fuel the open ocean. They are plentiful and serve as food for many larger predatory fishes, including tuna and marlin, marine mammals such as dolphins and whales, and marine birds," Cortesi said.

These kinds of fish also engage in one of the biggest daily migrations in the animal kingdom. They swim near the surface at night to feed in plankton-rich waters, then return to the depths - 650 to 3,280 feet (200 to 1,000 meters) - during daytime to avoid predation.

"The deep sea remains a frontier for human exploration, a mystery box with the potential for significant discoveries," Cortesi said. "We should look after this habitat with the utmost care to make sure future generations can continue to marvel at its wonders."

Varieties

Japan City Gets $3.6 Mn Donation in Gold to Fix Water System

FILE PHOTO: Factories line the port of Osaka, western Japan October 23, 2017. REUTERS/Thomas White/File Photo
FILE PHOTO: Factories line the port of Osaka, western Japan October 23, 2017. REUTERS/Thomas White/File Photo
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Japan City Gets $3.6 Mn Donation in Gold to Fix Water System

FILE PHOTO: Factories line the port of Osaka, western Japan October 23, 2017. REUTERS/Thomas White/File Photo
FILE PHOTO: Factories line the port of Osaka, western Japan October 23, 2017. REUTERS/Thomas White/File Photo

Osaka has received an unusual donation -- 21 kilograms of gold -- to pay for the maintenance of its ageing water system, the Japanese commercial hub announced Thursday.

The donation worth $3.6 million was made in November by a person who a month earlier had already given $3,300 in cash for the municipal waterworks, Osaka Mayor Hideyuki Yokoyama told a press conference.

"It's an absolutely staggering amount," said Yokoyama, adding that he was lost for words to express his gratitude.

"I was shocked."

The donor wished to remain anonymous, AFP quoted the mayor as saying.

Work to replace water pipes in Osaka, a city of 2.8 million residents, has hit a snag as the actual cost exceeded the planned budget, according to local media.