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New Gravitational Insights Unveil Mysterious Relationship Between Satellites and Earth’s Core Cycles

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At an altitude close to 35,786 kilometers above the equator, a satellite circling the Earth moves at a speed of 3.07 kilometers per second and completes an orbit around the Earth in exactly one sidereal day. This means that such a satellite would appear motionless to an observer on the ground, making it geostationary if it follows the direction of Earth’s rotation. For that reason, communication, weather, or navigation satellites are often placed in geostationary orbits.

The gravitational tides induced by the Moon and the Sun, as well as the gravitational correction from the equatorial bulge induced by Earth’s rotation, generate precession of the orbital plane of geostationary satellites, with a period of 53 years and an initial rate of inclination change by about 0.85 degrees per year. This amounts to 1.63 times the angular diameter of the Moon every year. To correct for this drift, station-keeping maneuvers by thrusters are needed with a velocity kick of about 50 meters per second every year.

Today, I realized that there is another source for a minor correction that was not appreciated before. A new Nature paper suggests that the Earth’s core follows a 70-year cycle during which its rotation slows down and speeds up. By conserving total angular momentum, this generates a counter-cycle in the Earth’s mantle and crust surrounding the core.

Revealing the “Dance” Between Satellites and Earth’s Core

The inner core of the Earth is a solid, crystalized iron sphere of 70% the size of the Moon. It floats about 5,150 kilometers under our feet in a sea of liquid iron, nickel and other metals known as the outer core. The central temperature of Earth is about 5,700 degrees Kelvin, similar to the surface temperature of the Sun.

The new study shows that the inner core began to slow down around the year 2010, moving slower than the Earth’s surface. This conclusion is based on data concerning the arrival times of seismic waves from 121 earthquakes in the South Sandwich Islands between 1991 and 2023 obtained by seismographs in Canada and Alaska, as well as shock wave data from Soviet nuclear tests conducted between 1971 and 1974.

The resulting drift in the rotation of the mantle translates to about a millisecond in the duration of a day over a period of several decades. Given the velocity of geostationary satellites, this change in the rotation period of the Earth’s crust generates a slip by a meter per decade for a fixed point on Earth’s surface relative to a geostationary satellite in an orbit designed based on the assumption of a constant rotation period of Earth.

This drift is much smaller than other known effects that are routinely corrected for by station-keeping maneuvers. However, it could potentially be searched for in positioning data on geostationary satellites as a new way to measure changes in the rotation period of Earth’s inner core.

One can imagine a more direct but less practical way to probe the Earth’s core. If Earth were to trap a primordial black hole with the mass of a kilometer-size asteroid, the event horizon of the black hole would be of the scale of an atomic nucleus, and so it could travel back and forth through Earth’s inner core with negligible dynamical friction. Scientists could then use the seismic signal from this motion to map the internal structure of the Earth as the black hole completes a full trip from one side of the Earth to the opposite side and back every 84 minutes.

In the absence of an ideal probe of this type, it is tempting to imagine digging a tunnel with an average length of 12,742 kilometers through Earth’s center. Such a tunnel would have allowed us to reach the other side of Earth in 42 minutes by free-fall.

This brings three benefits. First, a straight line is the shortest path to the other side, with a length equal to the Earth’s diameter instead of (pi/2)=1.57 times this diameter as needed for an international flight around the Earth. Second, the journey’s duration of 42 minutes is shorter than with any other transportation vehicle at our disposal. And third, free fall is powered by gravity and does not require any fuel. The first 21 minutes of the journey will involve acceleration, followed by 21 minutes of deceleration after crossing Earth’s center, all the way to a full stop on the other side.

There is no better green-energy solution to travel around the globe. Unfortunately, no construction material would withstand the heat from the core at 5700 degrees, and the changing rotation of the inner core would twist the shape of such a tunnel as if it were chewing gum on a spinning wheel.

A less futuristic concept for travel is a space elevator. Here, a cable fixed to the equator and reaching out to pace has a counterweight at its upper end, which could keep its center of mass at the altitude of a geostationary orbit. In that arrangement, the cable would be kept upright by the upward centrifugal force induced by the rotation and an elevator can carry cargo up and down the cable. The main challenge for realizing this concept involves the required material strength of the cable, which cannot be met by known materials.

If humans ever inhabit smaller objects in space, like asteroids or moons, the same physical principles could be employed by space engineers to construct tunnels or space elevators on these platforms. Unlike the legal system, which varies geographically among different nations, the laws of physics are universal and cannot be broken. Imagining new applications of these laws is what makes us fragile creatures born on a tiny rock left over from the formation of the Sun so powerful. As Albert Einstein noted: “imagination embraces the entire world, stimulating progress, giving birth to evolution.”

Avi Loeb is the head of the Galileo Project, founding director of Harvard University’s – Black Hole Initiative, director of the Institute for Theory and Computation at the Harvard-Smithsonian Center for Astrophysics, and the former chair of the astronomy department at Harvard University (2011-2020). He is a former member of the President’s Council of Advisors on Science and Technology and a former chair of the Board on Physics and Astronomy of the National Academies. He is the bestselling author of “Extraterrestrial: The First Sign of Intelligent Life Beyond Earth” and a co-author of the textbook “Life in the Cosmos,” both published in 2021. His new book, titled “Interstellar,” was published in August 2023.

 

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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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