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Narrowing down the source of the dinosaur-killer asteroid – SYFY WIRE

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Where did the dinosaur-killer asteroid come from?

This is a question of great scientific and titillating public interest. We know that 66 million years ago an asteroid 10 kilometers in size slammed into the Earth just off the coast of what is now the Yucatan Peninsula in the Gulf of Mexico, carving out the 180-kilometer-wide Chicxulub crater and setting off a complicated chain of events that killed off something like 75% of all species on the planet including all the non-avian dinosaurs, so yeah, understanding it seems important.

For a while it was thought it could be a comet, but samples of the impactor retrieved from various sites around the world dated to the time of the impact strongly suggest it was a kind of asteroid called a carbonaceous chondrite. A chondritic asteroid is one that is primitive, formed when the solar system was very young, and is composed of small grains of material that haven’t undergone any real change since. Chondrites make up the vast majority of meteorites that fall to Earth, more than 80%. On the other hand, carbonaceous ones, which are high in carbon content and therefore dark, are pretty rare, making up just 3-5% of meteorites that fall to Earth.

So the impactor comes from a rare population of asteroid. Here’s where things get a little strange: When you look at the biggest craters on Earth, presumably from the biggest asteroids, something like half look to be produced by carbonaceous chondrites. So while they’re rare overall, the big ones seem to like hitting Earth.

Also, it’s known that these kinds of big dark asteroids tend to orbit in the outer part of the asteroid belt, farther from the Sun. Yet theoretical studies have shown that we should expect very few impactors from that part of the belt.

So we have contradictory ideas here. Where are these big dark rocks coming from? And how often do they hit us?

To investigate, a team of astronomers modeled how asteroids in the main belt behave. This has been done before, but they did something a little different.

What they wanted to find out was how main belt asteroids get knocked into orbits that get them near Earth (too near, if you know what I mean). In general this is due to the gravity of Jupiter, which has a strong effect, but is limited to certain regions of the belt — what are called resonances, where the asteroid’s orbital period is a simple ratio of Jupiter’s. In this case, the asteroid orbits the Sun, say, three times for every once Jupiter does, or 8 to 3, or 5 to 2. When that happens the rock gets a periodic kick in orbital energy from the giant planet, and that can, over time, send it plummeting down toward the Sun … and Earth.

Another force is called the YORP effect, and is due to sunlight subtly influencing the asteroid’s orbit. This has been modeled many times, but in general the models have concentrated on the parts of the belt where the resonance effects are strongest.

What’s new here is the team looked at the entire asteroid belt as a potential source of big, dark, threatening rocks. They also looked preferentially at big rocks, ones with a diameter 5 kilometers or larger, and that also orbit the Sun farther out than 375 million kilometers on average; using real data from the WISE observatory (an infrared satellite that observed asteroids) that means 42,721 objects.

They used computer simulations to model the physics of how the asteroids move over the course of a billion years, including effects from all the planets (except wee Mercury, which is too small to affect them) and the YORP effect. In general, YORP changes an asteroid’s orbit very slowly over time until it gets into a resonance, and then the rock gets moved rapidly into a new and potentially threatening orbit.

What they found is surprising. About half of the main belt big rocks that get moved into near-Earth orbits come from the middle to outer parts of the asteroid belt! This is 10 times higher than previous estimates, which said asteroids from this part of the belt were rare. But this jibes with the result that something like half the big rocks that hit us are carbonaceous chondrites, since those come from the outer belt. If true, this resolves that tension. They find that the chances of the dinosaur killer coming from the middle to outer main belt are 60%.

They also found that one asteroid 5 kilometers wide or larger escapes from the main belt into a near-Earth trajectory roughly every 100,000 years. Those tend to break up or fall into the Sun after about a hundred million years or less, but some impact the inner planets. According to their simulations, we can expect roughly 25 impacts from asteroids bigger than 5 km in size every billion years, or about one every 40 million years. A dinosaur killer 10 km in size is more rare, once every 250 – 500 million years. Those numbers line up fairly well with what’s seen as far as big impacts on Earth.

So does this solve the mystery? Well, kinda. It does show that a lot more rocks from the outer belt can eventually hit us, which is a big step. There are hints that while big dark rocks come from the outer belt, smaller dark ones come from the inner belt, which suggests the forces acting on these rocks is different for different parts of the belt. Also, the inner belt seems to produce fewer big rocks that can impact us than older models predicted. It’s not clear why.

There are still lots of things left to figure out here, but that’s typical. It takes massive computers a long time to do the simulations, so as they get faster it becomes easier to run various models and change parameters. In general that means we learn more since new things are tried and found to work… or importantly not to work, since sometimes old ideas turn out not to be right. That’s science.

Every step we take here gets us a little bit closer to understanding what happened all those millions of years ago when the dinosaurs had a Very Bad Day™. If we want to make sure we have a future — at least concerning asteroid impacts — then learning more about the behavior of these rocks is a Very Good Idea.

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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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