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The magnetic shield that protects Earth and makes life possible

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We often take the most important things for granted. For example, when was the last time you thought about Earth’s magnetic field, if ever? Besides pointing compass needles northward or directing migrating birds, does Earth’s magnetic field have any other effect on our daily lives?

Spoiler alert: every second, Earth’s magnetic field deflects about 1.5 million tons of material ejected from the Sun at high speed. If it were not there, the atmosphere would suffer direct and continuous erosion. It would not be able to avoid the direct impact of those solar particles, which would sweep everything that protects us away with them. Therefore, without Earth’s magnetic field, life as we know it would not exist on the surface of our planet. Of course, our technological societies would not be possible either, since the magnetic field also protects our electronic equipment, not just our DNA, from this same bombardment.

Earth (like Mercury, Jupiter, Saturn, Neptune, and Uranus) is surrounded by a relatively intense magnetic field that originates, for the most part, within the planet. It is believed that, at the current stage of Earth’s evolution, it is powered by the cooling and crystallization of the core. This agitates the liquid iron that surrounds it, creating powerful electrical currents that generate the magnetic field that extends into space. This type of magnetic field is known as a geodynamo, and the force field structure that deflects most of the solar wind and forms a protective shield is called the magnetosphere.

To understand how it works in more detail, let’s now travel about 80 kilometers (50 miles) above our heads. At that altitude, something fundamental happens. And a significant fraction of the gas in this region is ionized. In other words, the gas particles have an electric charge, generally because they have lost an electron in their structure due to the energetic radiation coming from our star. Charged particles behave in a very special way. They follow the magnetic field lines and, therefore, they move as if they were in lanes on a highway.

Before we continue, it is important to point out that the Sun, like all stars, ejects large amounts of material in the form of charged particles at very high speed. It does this in addition to electromagnetic energy across the entire range — our eyes are only sensitive to visible light, which is a very narrow range. This is what is known as stellar wind; or solar wind, in the case of our star. The connection between the magnetosphere and the solar wind is the heart of what is known as space weather.

If we could visualize Earth’s magnetic field, we would see that it is what we scientists call a dipolar magnetic field. This is where the lines of force leave one hemisphere and enter the other. In normal convention, the outgoing field lines are magnetic north and the incoming field lines are magnetic south. In the case of the Earth, sometimes to avoid confusion with geographic north, the convention is reversed and the magnetic north pole points south and the magnetic south pole points north. In the north, the field lines point inward, which is the opposite of what happens in magnets. The field is also inclined 11.5 degrees with respect to the planet’s axis of rotation, which is what defines the geographical north and south poles.

A fascinating structure

The Earth’s magnetic field is twice as intense at the poles as at the equator. We know this thanks to instruments on satellites that have explored both the intensity and direction of Earth’s magnetic field and confirmed its dipole-shaped nature. In addition to being complex, the form it takes is variable. Some of its components are the Van Allen radiation belts, the ring current, the magnetic tail, and the magnetopause.

Among just a few fascinating details of the structure of the magnetic field that surrounds our planet is a region that is made up of cold, dense plasma that rotates with the Earth. The Van Allen belts are also out there, where particles move with relativistic energies, in other words, close to the speed of light.

In what is known as the ring current, energetic ions move at much slower speed than in the Van Allen belts, but they have a higher density and produce an electric current that surrounds the Earth. Electrons move from the twilight zone to the zone where it is night and positively charged ions move in the opposite direction. This ring current generates a magnetic field that points in the opposite direction of the Earth’s magnetic field and that, when it becomes intense, decreases the intensity of the field measured on the surface. There are more currents that connect the ring current to the ionosphere and play an essential role in the northern lights and space weather.

To understand the global configuration of the way particles move in our space environment, we need one more fundamental ingredient. The solar wind is also magnetic. A way to simply visualize this interaction is to imagine the solar wind as the current of a river and the Earth and its magnetic field as a giant stone. Since the solar wind is supersonic we have a bow shock and behind the obstacle we have the tail. In this case, it is a magnetic tail. As for magnetic storms and where they come from, we will leave those for another occasion.

 

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Here’s how Helene and other storms dumped a whopping 40 trillion gallons of rain on the South

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More than 40 trillion gallons of rain drenched the Southeast United States in the last week from Hurricane Helene and a run-of-the-mill rainstorm that sloshed in ahead of it — an unheard of amount of water that has stunned experts.

That’s enough to fill the Dallas Cowboys’ stadium 51,000 times, or Lake Tahoe just once. If it was concentrated just on the state of North Carolina that much water would be 3.5 feet deep (more than 1 meter). It’s enough to fill more than 60 million Olympic-size swimming pools.

“That’s an astronomical amount of precipitation,” said Ed Clark, head of the National Oceanic and Atmospheric Administration’s National Water Center in Tuscaloosa, Alabama. “I have not seen something in my 25 years of working at the weather service that is this geographically large of an extent and the sheer volume of water that fell from the sky.”

The flood damage from the rain is apocalyptic, meteorologists said. More than 100 people are dead, according to officials.

Private meteorologist Ryan Maue, a former NOAA chief scientist, calculated the amount of rain, using precipitation measurements made in 2.5-mile-by-2.5 mile grids as measured by satellites and ground observations. He came up with 40 trillion gallons through Sunday for the eastern United States, with 20 trillion gallons of that hitting just Georgia, Tennessee, the Carolinas and Florida from Hurricane Helene.

Clark did the calculations independently and said the 40 trillion gallon figure (151 trillion liters) is about right and, if anything, conservative. Maue said maybe 1 to 2 trillion more gallons of rain had fallen, much if it in Virginia, since his calculations.

Clark, who spends much of his work on issues of shrinking western water supplies, said to put the amount of rain in perspective, it’s more than twice the combined amount of water stored by two key Colorado River basin reservoirs: Lake Powell and Lake Mead.

Several meteorologists said this was a combination of two, maybe three storm systems. Before Helene struck, rain had fallen heavily for days because a low pressure system had “cut off” from the jet stream — which moves weather systems along west to east — and stalled over the Southeast. That funneled plenty of warm water from the Gulf of Mexico. And a storm that fell just short of named status parked along North Carolina’s Atlantic coast, dumping as much as 20 inches of rain, said North Carolina state climatologist Kathie Dello.

Then add Helene, one of the largest storms in the last couple decades and one that held plenty of rain because it was young and moved fast before it hit the Appalachians, said University of Albany hurricane expert Kristen Corbosiero.

“It was not just a perfect storm, but it was a combination of multiple storms that that led to the enormous amount of rain,” Maue said. “That collected at high elevation, we’re talking 3,000 to 6000 feet. And when you drop trillions of gallons on a mountain, that has to go down.”

The fact that these storms hit the mountains made everything worse, and not just because of runoff. The interaction between the mountains and the storm systems wrings more moisture out of the air, Clark, Maue and Corbosiero said.

North Carolina weather officials said their top measurement total was 31.33 inches in the tiny town of Busick. Mount Mitchell also got more than 2 feet of rainfall.

Before 2017’s Hurricane Harvey, “I said to our colleagues, you know, I never thought in my career that we would measure rainfall in feet,” Clark said. “And after Harvey, Florence, the more isolated events in eastern Kentucky, portions of South Dakota. We’re seeing events year in and year out where we are measuring rainfall in feet.”

Storms are getting wetter as the climate change s, said Corbosiero and Dello. A basic law of physics says the air holds nearly 4% more moisture for every degree Fahrenheit warmer (7% for every degree Celsius) and the world has warmed more than 2 degrees (1.2 degrees Celsius) since pre-industrial times.

Corbosiero said meteorologists are vigorously debating how much of Helene is due to worsening climate change and how much is random.

For Dello, the “fingerprints of climate change” were clear.

“We’ve seen tropical storm impacts in western North Carolina. But these storms are wetter and these storms are warmer. And there would have been a time when a tropical storm would have been heading toward North Carolina and would have caused some rain and some damage, but not apocalyptic destruction. ”

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Follow AP’s climate coverage at https://apnews.com/hub/climate

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Follow Seth Borenstein on Twitter at @borenbears

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Associated Press climate and environmental coverage receives support from several private foundations. See more about AP’s climate initiative here. The AP is solely responsible for all content.

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‘Big Sam’: Paleontologists unearth giant skull of Pachyrhinosaurus in Alberta

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It’s a dinosaur that roamed Alberta’s badlands more than 70 million years ago, sporting a big, bumpy, bony head the size of a baby elephant.

On Wednesday, paleontologists near Grande Prairie pulled its 272-kilogram skull from the ground.

They call it “Big Sam.”

The adult Pachyrhinosaurus is the second plant-eating dinosaur to be unearthed from a dense bonebed belonging to a herd that died together on the edge of a valley that now sits 450 kilometres northwest of Edmonton.

It didn’t die alone.

“We have hundreds of juvenile bones in the bonebed, so we know that there are many babies and some adults among all of the big adults,” Emily Bamforth, a paleontologist with the nearby Philip J. Currie Dinosaur Museum, said in an interview on the way to the dig site.

She described the horned Pachyrhinosaurus as “the smaller, older cousin of the triceratops.”

“This species of dinosaur is endemic to the Grand Prairie area, so it’s found here and nowhere else in the world. They are … kind of about the size of an Indian elephant and a rhino,” she added.

The head alone, she said, is about the size of a baby elephant.

The discovery was a long time coming.

The bonebed was first discovered by a high school teacher out for a walk about 50 years ago. It took the teacher a decade to get anyone from southern Alberta to come to take a look.

“At the time, sort of in the ’70s and ’80s, paleontology in northern Alberta was virtually unknown,” said Bamforth.

When paleontogists eventually got to the site, Bamforth said, they learned “it’s actually one of the densest dinosaur bonebeds in North America.”

“It contains about 100 to 300 bones per square metre,” she said.

Paleontologists have been at the site sporadically ever since, combing through bones belonging to turtles, dinosaurs and lizards. Sixteen years ago, they discovered a large skull of an approximately 30-year-old Pachyrhinosaurus, which is now at the museum.

About a year ago, they found the second adult: Big Sam.

Bamforth said both dinosaurs are believed to have been the elders in the herd.

“Their distinguishing feature is that, instead of having a horn on their nose like a triceratops, they had this big, bony bump called a boss. And they have big, bony bumps over their eyes as well,” she said.

“It makes them look a little strange. It’s the one dinosaur that if you find it, it’s the only possible thing it can be.”

The genders of the two adults are unknown.

Bamforth said the extraction was difficult because Big Sam was intertwined in a cluster of about 300 other bones.

The skull was found upside down, “as if the animal was lying on its back,” but was well preserved, she said.

She said the excavation process involved putting plaster on the skull and wooden planks around if for stability. From there, it was lifted out — very carefully — with a crane, and was to be shipped on a trolley to the museum for study.

“I have extracted skulls in the past. This is probably the biggest one I’ve ever done though,” said Bamforth.

“It’s pretty exciting.”

This report by The Canadian Press was first published Sept. 25, 2024.

The Canadian Press. All rights reserved.

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The ancient jar smashed by a 4-year-old is back on display at an Israeli museum after repair

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TEL AVIV, Israel (AP) — A rare Bronze-Era jar accidentally smashed by a 4-year-old visiting a museum was back on display Wednesday after restoration experts were able to carefully piece the artifact back together.

Last month, a family from northern Israel was visiting the museum when their youngest son tipped over the jar, which smashed into pieces.

Alex Geller, the boy’s father, said his son — the youngest of three — is exceptionally curious, and that the moment he heard the crash, “please let that not be my child” was the first thought that raced through his head.

The jar has been on display at the Hecht Museum in Haifa for 35 years. It was one of the only containers of its size and from that period still complete when it was discovered.

The Bronze Age jar is one of many artifacts exhibited out in the open, part of the Hecht Museum’s vision of letting visitors explore history without glass barriers, said Inbal Rivlin, the director of the museum, which is associated with Haifa University in northern Israel.

It was likely used to hold wine or oil, and dates back to between 2200 and 1500 B.C.

Rivlin and the museum decided to turn the moment, which captured international attention, into a teaching moment, inviting the Geller family back for a special visit and hands-on activity to illustrate the restoration process.

Rivlin added that the incident provided a welcome distraction from the ongoing war in Gaza. “Well, he’s just a kid. So I think that somehow it touches the heart of the people in Israel and around the world,“ said Rivlin.

Roee Shafir, a restoration expert at the museum, said the repairs would be fairly simple, as the pieces were from a single, complete jar. Archaeologists often face the more daunting task of sifting through piles of shards from multiple objects and trying to piece them together.

Experts used 3D technology, hi-resolution videos, and special glue to painstakingly reconstruct the large jar.

Less than two weeks after it broke, the jar went back on display at the museum. The gluing process left small hairline cracks, and a few pieces are missing, but the jar’s impressive size remains.

The only noticeable difference in the exhibit was a new sign reading “please don’t touch.”

The Canadian Press. All rights reserved.

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