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Rare dark-streaked meteorites may come from a 'potentially hazardous' asteroid – Space.com

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Strange, dark-veined meteorites rained down on Earth when a fireball exploded over Chelyabinsk, Russia, in February 2013. The origin of these unusual meteorites has remained a mystery, but now, planetary scientists have discovered a possible source: a mile-and-a-half-long near-Earth asteroid.

Scientists know that the dark streaks across the Chelyabinsk meteorites are caused by a process called shock darkening. Yet only around 2% of a common type of meteorite called chondrite meteorites show signs of shock darkening, and the source of these space rocks has remained a mystery.

Now, scientists have identified the asteroid 1998 OR2 as a potential source of shock-darkened meteorites. The near-Earth asteroid was discovered in July 1998 by the Near-Earth Asteroid Tracking program at NASA’s Jet Propulsion Laboratory. Its last close approach to Earth was in April 2020, when the space rock passed within 3.9 million miles (6.3 million kilometers) of our planet.

Related: Mile-long asteroid 1998 OR2 dons ‘mask’ before Earth flyby (photos)

Although that may not seem very close, NASA still considers 1998 OR2 “potentially hazardous” because changes to the asteroid’s orbit over the next 1,000 years could make it a risk to Earth.

Meteorites are created when pieces of an asteroid like 1998 OR2 break away and enter Earth’s atmosphere. The discovery that shock-darkened meteorites can originate from a near-Earth asteroid hints at the varying material strength of asteroids and has implications for protecting Earth against a potential impact, the researchers said.

“Shock darkening is an alteration process caused when something impacts a planetary body hard enough that the temperatures partially or fully melt those rocks and alter their appearance both to the human eye and in our data,” Adam Battle, a graduate student in planetary science at the University of Arizona and lead author of the study, said in a statement (opens in new tab). “This process has been seen in meteorites many times but has only been seen on asteroids in one or two cases way out in the main asteroid belt, which is found between Mars and Jupiter.”

Vishnu Reddy, a planetary scientist at the University of Arizona and co-author of the new study who detected shock darkening on these main-belt asteroids, said that it’s a much more common phenomenon on asteroids than meteorites. “Impacts are very common in asteroids and any solid body in the solar system because we see impact craters on these objects from spacecraft images,” he said in the statement. “But impact melt and shock-darkening effects on meteorites derived from these bodies are rare.”

Reddy, who co-leads the Space Domain Awareness lab at the Lunar and Planetary Laboratory, added that finding a near-Earth asteroid dominated by this process has implications for impact hazard assessment. 

“Adam [Battle]’s work has shown that ordinary chondrite asteroids can appear as carbonaceous in our classification tools if they are affected by shock darkening,” Reddy said. “These two materials have different physical strengths, which is important when trying to deflect a hazardous asteroid.”

Is asteroid 1998 OR2 chondrite or carbonaceous? 

Reddy, Battle and their team used the Rapid Astronomical Pointing Telescopes for Optical Reflectance Spectroscopy (RAPTORS) atop the Kuiper Space Sciences Building on the University of Arizona campus to observe the asteroid 1998 OR2.

The team collected data on 1998 OR2’s surface composition, with the asteroid visually appearing as an ordinary chondrite asteroid, a type of space rock that is light in color and contains the minerals olivine and pyroxene. But an asteroid classification tool determined that 1998 OR2 appeared to be a carbonaceous asteroid ; these space rocks are dark and featureless compared with chondrite asteroids.

The team then set about investigating the reason for this discrepancy and determining the correct classification.

“The mismatch was one of the early things that got the project going to investigate potential causes for the discrepancy,” Battle said.

They eliminated the possibility that exposure to the space environment had caused changes in the asteroid’s surface, as this process, called space weathering, would have left the space rock slightly reddened. 

The team concluded that shock darkening was responsible for the disparity between the two analysis methods, because the shock darkening process can obscure olivine and pyroxene while darkening the asteroid’s surface, thus making it look like a carbonaceous asteroid.

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“The asteroid is not a mixture of ordinary chondrite and carbonaceous asteroids, but rather it is definitely an ordinary chondrite, based on its mineralogy, which has been altered — likely through the shock darkening process — to look like a carbonaceous asteroid to the classification tool,” Battle said.

Shock darkening of asteroids was first theorized in the late 20th century but wasn’t an intense area of study until the 2013 Chelyabinsk fireball seeded Earth with shock-darkened meteorites.

Interest in shock darkening grew after Reddy found asteroids affected by the process in the main asteroid belt. This new discovery showing evidence of the process in a near-Earth asteroid could further increase interest in shock darkening, the team said.

The research was published Oct. 4 in The Planetary Science Journal and presented at a conference held this week by the American Astronomical Society’s Division of Planetary Sciences..

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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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