What are auroras, and why do they come in different shapes and colors? Two experts explain

MARCH 29, 2023, by B. Carter & E. MacDonald, The Conversation

https://phys.org/news/2023-03-auroras-experts.html

Credit: Pixabay/CC0 Public Domain

Over millennia, humans have observed and been inspired by beautiful displays of light bands dancing across dark night skies. Today, we call these lights the aurora: the aurora borealis in the northern hemisphere, and the aurora australis in the south.

Nowadays, we understand auroras are caused by charged particles from Earth's magnetosphere and the solar wind colliding with other particles in Earth's upper atmosphere. Those collisions excite the atmospheric particles, which then release light as they "relax" back to their unexcited state.

The color of the light corresponds to the release of discrete chunks of energy by the atmospheric particles, and is also an indicator of how much energy was absorbed in the initial collision.

The frequency and intensity of auroral displays is related to activity on the sun, which follows an 11-year cycle. Currently, we are approaching the next maximum, which is expected in 2025.

Connections to the sun

Such displays have long been documented by peoples throughout North America, Europe, Asia and Australia.

In the 17th century, scientific explanations for what caused the aurora began to surface. Possible explanations included air from Earth's atmosphere rising out of Earth's shadow to become sunlit (Galileo in 1619) and light reflections from high-altitude ice crystals (Rene Descartes and others).

https://youtu.be/sN5goxeTfjc

Fox Fires, a short film inspired by the Finnish folk tale of the aurora borealis.

In 1716, English astronomer Edmund Halley was the first to suggest a possible connection with Earth's magnetic field. In 1731, a French philosopher named Jean-Jacques d'Ortous de Mairan noted a coincidence between the number of sunspots and aurora. He proposed that the aurora was connected with the sun's atmosphere.

It was here that the connection between activity on the sun was linked with auroras here on Earth, giving rise to the areas of science now called "heliophysics" and "space weather".

Earth's magnetic field as a particle trap

The most common source of aurora is particles traveling within Earth's magnetosphere, the region of space occupied by Earth's natural magnetic field.

Images of Earth's magnetosphere typically show how the magnetic field "bubble" protects Earth from space radiation and repels most disturbances in the solar wind. However, what is not normally highlighted is the fact that Earth's magnetic field contains its own population of electrically charged particles (or "plasma").

https://youtu.be/DyuTyEw3etk

Model representation of Earth’s magnetic field interacting with the solar wind.

The magnetosphere is composed of charged particles that have escaped from Earth's upper atmosphere and charged particles that have entered from the solar wind. Both types of particles are trapped in Earth's magnetic field.

The motions of electrically charged particles are controlled by electric and magnetic fields. Charged particles gyrate around magnetic field lines, so when viewed at large scales magnetic field lines act as "pipelines" for charged particles in a plasma.

The Earth's magnetic field is similar to a standard "dipole" magnetic field, with field lines bunching together near the poles. This bunching up of field lines actually alters the particle trajectories, effectively turning them around to go back the way they came, in a process called "magnetic mirroring".

Earth's magnetosphere in a turbulent solar wind

During quiet and stable conditions, most particles in the magnetosphere stay trapped, happily bouncing between the south and north magnetic poles out in space. However, if a disturbance in the solar wind (such as a coronal mass ejection) gives the magnetosphere a "whack", it becomes disturbed.

https://youtu.be/Sf1MGTD9xGY

‘Magnetic mirroring’ makes charged particles bounce back and forth between the poles.

The trapped particles are accelerated and the magnetic field "pipelines" suddenly change. Particles that were happily bouncing between north and south now have their bouncing location moved to lower altitudes, where Earth's atmosphere becomes more dense.

As a result, the charged particles are now likely to collide with atmospheric particles as they reach the polar regions. This is called "particle precipitation". Then, when each collision occurs, energy is transferred to the atmospheric particles, exciting them. Once they relax, they emit the light that forms the beautiful aurora we see.
Curtains, colors and cameras

The amazing displays of aurora dancing across the sky are the result of the complex interactions between the solar wind and the magnetosphere.

Aurora appearing, disappearing, brightening and forming structures like curtains, swirls, picket fences and traveling waves are all visual representations of the invisible, ever-changing dynamics in Earth's magnetosphere as it interacts with the solar wind.

https://youtu.be/0xUF82rVljE

Catching aurora in the southern hemisphere.

As these videos show, aurora comes in all sorts of colors.

The most common are the greens and reds, which are both emitted by oxygen in the upper atmosphere. Green auroras correspond to altitudes close to 100 km, whereas the red auroras are higher up, above 200 km.

Blue colors are emitted by nitrogen—which can also emit some reds. A range of pinks, purples and even white light are also possible due to a mixture of these emissions.

The aurora is more brilliant in photographs because camera sensors are more sensitive than the human eye. Specifically, our eyes are less sensitive to color at night. However, if the aurora is bright enough it can be quite a sight for the naked eye.

Where and when?

Even under quiet space weather conditions, aurora can be very prominent at high latitudes, such as in Alaska, Canada, Scandinavia and Antarctica. When a space weather disturbance takes place, auroras can migrate to much lower latitudes to become visible across the continental United States, central Europe and even southern and mainland Australia.

https://youtu.be/uRufGWOiWmI

A rare sighting of the aurora australis from central Australia, with Uluru in the foreground.

The severity of the space weather event typically controls the range of locations where the aurora is visible. The strongest events are the most rare.

So, if you're interested in hunting auroras, keep an eye on your local space weather forecasts (US, Australia, UK, South Africa and Europe). There are also numerous space weather experts on social media and even aurora-hunting citizen science projects (such as Aurorasaurus) that you can contribute towards!

Get outside and witness one of nature's true natural beauties—aurora, Earth's gateway to the heavens.

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Elon Musk drops 'extraordinary' bombshell on AI dangers

https://www.youtube.com/watch?v=yPOEr7JDze4

29, March, 2023

 https://youtu.be/yPOEr7JDze4

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Solar Storm Tornados, Terrorism and Magnetic Pole Shift

Suspicious 0bserver

Mar 28, 2023

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Space News: Glass beads on Moon's surface may contain water - study

  Tues

Glass beads on Moon's surface may contain water - study

Scientists found water inside glass beads formed during impact events.

By JERUSALEM POST STAFF, MARCH 27, 2023

https://www.jpost.com/science/article-735393

A view of the "super Moon" is seen from Veracruz, Mexico, May 5, 2012.

(photo credit: REUTERS/MARTIN LARA REYNA)

Glass beads that were formed from the cooling of melted matter from impacts and strewn across the Moon may store significant amounts of water, a new study found.

The peer-reviewed study, published on Monday in the journal Nature Geoscience, was the result of analyses of samples from China's Chang'e-5 mission. The findings indicate that the Moon's soils contain a higher amount of solar wind-derived water than previously believed.

“The Pb-Pb dating of the CE5 impact glass beads indicates that they were formed in the range of 4-2,000 Ma by various local meteoritic impacts,” the researchers noted.

The Moon was once thought to be dry, but analyses of samples from the Apollo missions showed that there was water trapped within minerals from inside the Moon and orbiters have detected the presence of water on the Moon's surface.

Scientists believe that the interaction of the solar wind with materials on the lunar surface could produce water and sustain a water cycle, but a reservoir of lunar surface water has not yet been identified.

Visitors stand near a replica of a lunar orbiter from China's lunar exploration program Chang'e-5 Mission during an exhibition inside the National Museum in Beijing, China, March 3, 2021. (credit: REUTERS/TINGSHU WANG)

Yutu 2 Discovers Glass Beads on the Moon - What It’s All About?

Scientists analyze samples collected on Moon mission

The researchers who conducted the study, including Hejiu Hui of Nanjing University and Sen Hu, analyzed the water content within glass beads formed during impact events and extracted from lunar soil samples collected during the Chang’e-5 mission.

“Two analytical sessions were designed to measure the water abundances and hydrogen isotope compositions of CE5 impact glass beads using a CAMECA NanoSIMS 50L at the IGGAS,” the scientists wrote. “In the first session, measurements at the cores and rims of CE5 impact glass beads were carried out to investigate the potential water zonation features in the glasses. In the second session, more-detailed profile measurements on five individual CE5 impact glasses were acquired, as well as several parallel measurements on other glass beads for cross checking. A liquid nitrogen cold trap was used to further improve the vacuum quality in the second session.”

The scientists found water inside the beads that is consistent with a solar wind origin.

The distribution of water within individual beads suggests that water can rapidly accumulate in the beads through diffusion over the course of a few years and be rapidly released.

The researchers said this presents a potential recharge mechanism for driving a water cycle on the surface of the Moon.

Moreover, they suggested that the water trapped in the beads could serve as a possible water resource for future Moon missions and that the beads could host similar water sources on other celestial bodies with no air.             

NASA announce water on the Moon's surface discovery

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1879 Battle of Rorke's Drift (medals, etc.)

Medals awarded to British soldier who was part of 1879 Battle of Rorke's Drift which was immortalised in Michael Caine film Zulu go on sale for £20,000

• Corporal Alfred Saxty was in the 150-strong British garrison that defied all odds
• The 22-year-old was promoted to the rank of Sergeant the day after the battle

Medals from one of the last-known survivors of the legendary Battle of Rorke's Drift - immortalised in the film Zulu - will go on sale next month.

The medals of Alfred Saxty, who was just 22 at the time of the famous battle on January 22 1879, are expected to fetch up to £20,000.

Saxty was one of just over 150 British and colonial troops who bravely defended the station of Rorke's Drift in South Africa.

They fought off up to 4,000 Zulu warriors in what is still recognised as one of the most famous battles in British Military history.

His campaign medals from his South African and Burmese campaigns will go on sale at auction house Noonans' sale of Orders, Decorations, Medals and Militaria next month.

Saxty's campaign medals from his South African and Burmese campaigns will go on sale (pictured: front and back of the two medals)

The medals of Anglo-Zulu war veteran Alfred Saxty (pictured far left with other Rorke's Drift survivors) will go on sale and are expected to fetch up to £20,000

Saxty, who served as a Corporal in 'B' Company of 2nd Battalion, 24th Foot, was one of the 'last few survivors' of the battle, which has since been the subject of several films; most notably the 1964 film Zulu, starring Michael Caine. 

the soldiers were awarded 11 Victoria Crosses for their efforts

After surviving the notorious battle, the very next day Saxty was promoted to the rank of Sergeant. 

He later served in Burma and India and was eventually discharged in February 1895 before dying in Newport, Wales, where he lived with his sister, in 1936, aged 77.

Christopher Mellor-Hill, Head of Client Liaison at Noonans, explained why his pair of campaign medals from South Africa and Burma were expected to fetch a high price.

He said: 'Alfred Saxty of 2nd Battalion, 24th Foot served as a Corporal in 'B' Company at the defence, and was one of the last few survivors, of Rorke's Drift.

Sir Michael Caine 

Documentation relating to Alfred Saxty, who had a military career spanning from 1876 to 1895

What happened at Rorke's Drift? How 150 British soldiers held off 4,000 Zulu warriors in 1879 battle

On January 11, 1879, a British force commanded by Lieutenant-General Lord Chelmsford invaded Zululand.

From 22 to 23 January, on the bank of the Buffalo River in Natal Province, South Africa a 140-strong British garrison successfully defended the Rorke's Drift mission station.

The British garrison was commanded by Lieutenant John Chard, Royal Engineers and Lieutenant Gonville Bromhead of the 24 Foot. 

The Zulus were commanded by Prince Dabulamanzi kaMapande. 

Lt Chard was the commanding officer and organised the epic defence which saw them defy all odds to see off the 4,000 fierce Zulu warriors.

Rorke's Drift inspired the 1964 Hollywood blockbuster starring Stanley Baker and Michael Caine

For 12 hours the British repelled the spear-carrying tribesmen with accurate shooting and brutal hand-to-hand combat. 

The Zulus, known for their bravery and ferocity, were eventually forced to retreat with 350 of their number killed compared to 17 British.

The defensive British force was rewarded by Queen Victoria's government with no fewer than 11 Victoria Crosses.

The battle was part of the wider Anglo-Zulu war took place during 1879.

'He was just 22 years old when he was involved in one of the most famous battles in British military history, which saw just over 150 British and colonial troops defend the South African hospital against attacks by 3,000 to 4,000 Zulu warriors in January 1879.

'In fact, Saxty was promoted to Sergeant the day after the defence. Medals linked to this conflict always attract substantial attention.'

Saxty was born at Buckland Dinham, near Frome in Somerset, and enlisted for 25 Brigade at Newport, Monmouthshire in September 1876, aged 19.

He was posted to the 2nd Battalion, 24th Foot at Brecon two days later and served in South Africa from 1 February 1878 to 12 January 1880, during the Anglo-Zulu War, fought between the British Empire and the Zulu Kingdom in 1879.

Britain eventually emerged victorious from the conflict, ending Zulu dominance in the region of southern Africa.

Saxty, along with 150 fellow British and colonial comrades, successfully defended the mission station of Rorke's Drift against sustained attacks from between 3,000 and 4,000 Zulu warriors over 12 hours of fierce fighting.

After seven months of service in the Mediterranean, Saxty's regiment moved to India in August 1880 and served in Burma between May 1886 and January 1887, before returning to India again.

After his service in the Burma campaign, Saxty re-engaged for the 1st Battalion, Bedfordshire Regiment at Madras in October 1887, 'for such term as shall complete 21 years' service.'

He transferred to the 2nd Battalion of that regiment on New Year's Day 1888 and then transferred to the 2nd Battalion, Royal Inniskilling Fusiliers on July 14 1891.

He was buried with military honours at St Wollos Cemetery, Newport, on July 15 1936.

Scientists uncover startling concentrations of pure DDT along seafloor off LA coast

MARCH 24, 2023, by Rosanna Xia

https://phys.org/news/2023-03-scientists-uncover-startling-pure-ddt.html

Credit: Pixabay/CC0 Public Domain

First it was the eerie images of barrels leaking on the seafloor not far from Catalina Island. Then the shocking realization that the nation's largest manufacturer of DDT had once used the ocean as a huge dumping ground—and that as many as half a million barrels of its acid waste had been poured straight into the water.

Now, scientists have discovered that much of the DDT—which had been dumped largely in the 1940s and '50s—never broke down. The chemical remains in its most potent form in startlingly high concentrations, spread across a wide swath of seafloor larger than the city of San Francisco.

"We still see original DDT on the seafloor from 50, 60, 70 years ago, which tells us that it's not breaking down the way that (we) once thought it should," said UC Santa Barbara scientist David Valentine, who shared these preliminary findings Thursday during a research update with more than 90 people working on the issue. "And what we're seeing now is that there is DDT that has ended up all over the place, not just within this tight little circle on a map that we referred to as Dumpsite Two."

These revelations confirm some of the science community's deepest concerns—and further complicate efforts to understand DDT's toxic and insidious legacy in California. Public calls for action have intensified since the Los Angeles Times reported in 2020 that dichlorodiphenyltrichloroethane, banned in 1972, is still haunting the marine environment today. Significant amounts of DDT-related compounds continue to accumulate in California condors and local dolphin populations, and a recent study linked the presence of this once-popular pesticide to an aggressive cancer in sea lions.

With a $5.6-million research boost from Congress, at the urging of Sen. Dianne Feinstein, D-Calif., numerous federal, state and local agencies have since joined with scientists and environmental nonprofits to figure out the extent of the contamination lurking 3,000 feet underwater. (Another $5.2 million, overseen by California Sea Grant, will be distributed this summer to kick off another 18 months of research.)

The findings so far have been one stunning development after another. A preliminary sonar-mapping effort led by the Scripps Institution of Oceanography identified at least 70,000 debris-like objects on the seafloor.

The U.S. Environmental Protection Agency, after combing through thousands of pages of old records, discovered that other toxic chemicals—as well as millions of tons of oil drilling waste—had also been dumped decades ago by other companies in more than a dozen areas off the Southern California coast.

"When the DDT was disposed, it is highly likely that other materials—either from the tanks on the barges, or barrels being pushed over the side of the barges—would have been disposed at the same time," said John Lyons, acting deputy director of the EPA's Region 9 Superfund Division. He noted that the new science being shared this week is critical to answering one of the agency's most burning questions: "Is the contamination moving? And is it moving in a way that threatens the marine environment or human health?"

In recent months, Valentine, whose research team had first brought this decades-old issue back into the public consciousness, has been mapping and collecting samples of the seafloor between the Los Angeles coast and Catalina.

Analysis of the sediment so far shows that the most concentrated layer of DDT is only about 6 centimeters deep—raising questions about just how easily these still-potent chemicals could be remobilized.

"Trawls, cable lays could reintroduce this stuff back up to the surface," Valentine said. "And animals feeding—if a whale goes down and burrows on the seafloor, that could kick stuff up."

On a chilly winter morning in between two storms, Valentine and a team of students boarded the RV/Yellowfin and set out to collect more seafloor samples along key points of a hot-spot map that they've been piecing together.

As his students sliced and cataloged each layer of mud, they gasped in wonder at the tiny worms, snails and sea stars that lived so deep under the sea. They squinted at each tube that came out of the water and laughed apprehensively when asked about all the chemicals they were possibly holding in their hands.

"The goal is to collect as much mud as possible so that we don't have to come back out every time we have a question," Valentine explained as the ship's mechanical pulley churned for the eighth time that day. "We are starting to build a really exceptional data set … that will help us understand the time history of how things were transported, how they were transformed, and what their ultimate fate is."

Other scientists have also been chipping away at the many pieces to this deep-ocean puzzle.

Thursday's research updates included plans for the next Scripps mapping expedition, which will scan the seafloor with advanced sonar technology and also take hundreds of thousands of photos. Microbiologists shared their latest studies into whether deep-sea microbes could possibly help biodegrade some of the contamination, and chemical oceanographers discussed the many ways they've been trying to identify "fingerprints" that could help determine where the DDT is coming from—and how and if it's moving.

Biological oceanographers, marine ecologists and fisheries scientists also started to connect some dots on the various organisms they've found living in the contaminated sediment, as well as the midwater species that could potentially move the chemicals from deeper waters up closer to the surface.

All of them noted that there were uncomfortably high concentrations of DDT and DDT-related compounds in the samples they studied. Even the "control" samples they tried to collect—as a way to compare what a normal sediment or fish sample farther away from the dumping area might look like—ended up riddled with DDT.

"This suggests to us, very preliminarily, that there's some connection potentially—there's connectivity in these deep food webs across the basins and across the system," said Lihini Aluwihare, a marine chemist at Scripps.

On top of all this research, the EPA has been developing its own sampling plan, in collaboration with a number of state and federal agencies, to get a grasp of the many other chemicals that had also been dumped into the ocean. The hope, officials said, is that the groundbreaking science now underway on the deep-ocean DDT dumping will ultimately inform how future investigations of other offshore dump sites—whether along the Southern California coast or elsewhere in the country—could be conducted.

Mark Gold, an environmental scientist at the Natural Resources Defense Council who has worked on the DDT problem since the 1990s, said that as he listened to the latest research discoveries, he couldn't help but think that "our nation's ocean dumpsites all have horrible contamination problems. And yet they are unmonitored."

There are also more shallow areas off the Palos Verdes coast and at the mouth of the Dominguez Channel that have been known DDT hot spots for decades. Figuring out how to clean up those contaminated areas in an underwater environment has been its own complicated saga.

For Katherine Pease at Heal the Bay, an environmental group that has been making sure the public remains engaged on this issue in substantive ways, these latest revelations have been eye-opening.

This is, after all, what it truly means to live with a forever chemical. After all these decades, scientists are still uncovering new and unsettling surprises about the full extent of the contamination.

"We're still grappling with this legacy of treating the ocean as a dumping ground," said Pease, Heal the Bay's science and policy director.

"And the public—whether they're folks that like to fish ... or people who like to swim and visit the ocean—we all need to understand the history that went on, as well as the impacts. And partly that's to learn ... to make sure that we're able to protect our public health, but also to think about how we are treating the ocean now, as well as into the future."

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