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Category: asteroid/comet impacts

Shocked quartz at the Younger Dryas onset (12.8 ka) supports cosmic airbursts/impacts contributing to North American megafaunal extinctions and collapse of the Clovis technocomplex

Shocked quartz grains are an accepted indicator of crater-forming cosmic impact events, which also typically produce amorphous silica along the fractures. Furthermore, previous research has shown that shocked quartz can form when nuclear detonations, asteroids, and comets produce near-surface or “touch-down” airbursts. When cosmic airbursts detonate with enough energy and at sufficiently low altitude, the resultant relatively small, high-velocity fragments may strike Earth’s surface with high enough pressures to generate thermal and mechanical shock that can fracture quartz grains and introduce molten silica into the fractures. Here, we report the discovery of shocked quartz grains in a layer dating to the Younger Dryas (YD) onset (12.8 ka) in three classic archaeological sequences in the Southwestern United States: Murray Springs, Arizona; Blackwater Draw, New Mexico; and Arlington Canyon, California. These sites were foundational in demonstrating that the extinction or observed population bottlenecks of many megafaunal species and the coeval collapse/reorganization of the Clovis technocomplex in North America co-occurred at or near the YD onset. Using a comprehensive suite of 10 analytical techniques, including electron microscopy (TEM, SEM, CL, and EBSD), we have identified grains with glass-filled fractures similar to shocked grains associated with nuclear explosions and 27 accepted impact craters of different ages (e.g., Meteor Crater, 50 ka; Chesapeake Bay, 35 Ma; Chicxulub, 66 Ma; Manicouagan, 214 Ma) and produced in 11 laboratory shock experiments. In addition, we used hydrocode modeling to explore the temperatures, pressures, and shockwave velocities associated with the airburst of a 100-m fragment of a comet and conclude that they are sufficient to produce shocked quartz. These shocked grains co-occur with previously reported peak concentrations in platinum, meltglass, soot, and nanodiamonds, along with microspherules, similar to those found in ~28 microspherule layers that are accepted as evidence for cosmic impact events, even in the absence of a known crater. The discovery of apparently thermally-altered shocked quartz grains at these three key archaeological sites supports a cosmic impact as a major contributing factor in the megafaunal extinctions and the collapse of the Clovis technocomplex at the YD onset.

Citation: Kennett JP, LeCompte MA, Moore CR, Kletetschka G, Johnson JR, Wolbach WS, et al. (2025)PLoS One 20: e0319840. https://doi.org/10.1371/journal.pone.

Editor: Talaat Abdel Hamid, National Research Centre, EGYPT

China to carry out asteroid defense system test in near future: chief scientist

China has recently unveiled its plan to initiate an experimental verification project to demonstrate and test the effectiveness of its asteroid defense system, and Wu Weiren, one of the country’s top space scientists, stressed the necessity of such project to the Global Times on Sunday, saying that from the perspective of safeguarding the Earth’s safety and the continuation of humanity, building asteroid defense capabilities is a shared task for all humankind, while calling on further international collaborative efforts against the threats posed by asteroid impact.

“As a responsible spacefaring nation, China has the responsibility, obligation, and capability to contribute Chinese wisdom, leverage Chinese strength, and systematically develop an asteroid detection and defense system, working together with the world to protect our planetary home,” Wu said. Wu is the chief designer of China’s lunar exploration program and director and chief scientist of the country’s Deep Space Exploration Laboratory (DSEL).

Wu outlined China’s asteroid exploration and defense system in detail for the first time at the third International Deep Space Exploration Conference, and during the event held from Thursday to Friday in Hefei, East China’s Anhui Province, Wu revealed that in the near future, China will conduct a kinetic impact demonstration and verification mission on an asteroid posing a potential threat to Earth.

1st known interstellar visitor ‘Oumuamua is an ’exo-Pluto‘ — a completely new class of object, scientists say

Instead of being a mix of water ice, rock and carbon-rich material left over from the formation of the solar system, ‘Oumuamua appears to be almost pure nitrogen ice. And rather than being a compact ball, the visitor is more elongated than any known body in the solar system and starkly different from the interstellar Comets and , the only other known interstellar visitors.

“‘Oumuamua is in a different category of object,” Desch told Space.com by email. “It’s much harder to find, but there are a lot more of them.”

Planets arise from the cloud of gas and dust left over after a star is born. The first few million years are chaotic as the growing worlds jostle for their place around the young star…

Scientists use Stephen Hawking theory to propose ‘black hole morsels’ — strange, compact objects that could reveal new physics

Violent black hole collisions may create black hole ‘morsels’ no larger than an asteroid — and these bizarre objects could pave the way to unlocking new physics, a study claims.

Space Threat: Massive Asteroid 2025 OW Approaches Earth | WION Pulse

Basically there are three meteorites in our solar system that may pass by earth but most likely far away from the earth. Even though this news site says it may hit earth I am not quite certain it will.

Asteroid 2025 OW, the size of a skyscraper, is tearing through space next week—and it’s coming perilously close to Earth. NASA says no impact risk this time, but astronomers are sounding the alarm: these cosmic flybys are more frequent and more dangerous than you think. See why we dodged disaster and what happens if luck runs out.

#asteroid #earth #wion.

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3I/ATLAS: Interstellar object ‘may be oldest comet ever seen’

A mystery interstellar object discovered last week is likely to be the oldest comet ever seen—possibly predating our solar system by more than 3 billion years, researchers say.

The “water ice-rich” visitor, named 3I/ATLAS, is only the third known object from beyond our solar system ever spotted in our cosmic neighborhood and the first to reach us from a completely different region of our Milky Way galaxy.

It could be more than 7 billion years old, according to University of Oxford astronomer Matthew Hopkins—who is discussing his findings at the Royal Astronomical Society’s National Astronomy Meeting (NAM 2025) in Durham—and may be the most remarkable interstellar visitor yet.

Astronomers say new interstellar visitor 3I/ATLAS is ‘very likely to be the oldest comet we have ever seen’

The thick disk is a band of our galaxy’s most ancient stars that sandwiches the thin disk, which formed more recently and contains our relatively young star, the sun, and the solar system.

“This is an object from a part of the galaxy we’ve never seen up close before,” University of Oxford astrophysicist Chris Lintott said. “We think there’s a two-thirds chance this comet is older than the solar system, and that it’s been drifting through interstellar space ever since.”

If 3I/ATLAS originates from the Milky Way’s thick stellar disk, and thus formed around an ancient star, this also has implications for its chemical composition. Hopkins and crew suggest the interstellar interloper may be rich in water ice.

When a comet hits a tidally locked exo-Earth

Comets that have hit Earth have been a mixed bag. Early in Earth’s history, during the solar system’s chaotic beginning, they were likely the source of our planet’s water, ultimately making up about 0.02% of the planet’s mass. (Mars and Venus received a similar fraction.)

Comets brought complex organic molecules and the biosphere, but later posed a threat to the same in cometary collisions. A (or asteroid) likely caused the Tunguska Event in 1908 in Russia, and a comet fragment likely triggered the rapid climate shift of the Younger Dryas 12,800 years ago, with its widespread extinctions.

If such collisions happen here, they likely take place in other solar systems as well. Now three scientists in the United Kingdom have modeled the impacts of an icy cometary collision with an Earth-like, tidally locked terrestrial planet. Such objects are prime candidates in the search for habitable exoplanets outside our solar system.

Life recovered rapidly at site of dino-killing asteroid. A hydrothermal system may have helped

About 66 million years ago, an asteroid slammed into the planet, wiping out all non-avian dinosaurs and about 70% of all marine species.

But the crater it left behind in the Gulf of Mexico was a literal hotbed for life, enriching the overlying ocean for at least 700,000 years, according to research published today in Nature Communications.

Scientists have discovered that a hydrothermal system created by the asteroid impact may have helped marine life flourish at the impact site by generating and circulating nutrients in the crater environment.

Tiny Fossils Reveal Mammals Left the Trees Long Before the Asteroid Impact

Millions of years before the asteroid impact that ended the reign of the dinosaurs, mammals were already beginning to shift from tree-dwelling to ground-based lifestyles.

A groundbreaking study uncovered this evolutionary trend by analyzing tiny limb bone fragments from marsupials and placental mammals in Western North America. These subtle fossil clues reveal that mammals may have been responding to a changing world, especially the spread of flowering plants that transformed habitats on the ground. Surprisingly, this terrestrial transition appears to have played a bigger role in mammalian evolution than direct interactions with dinosaurs.

Early Ground-Dwellers Before Dinosaurs’ Demise.

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