At least two mass extinction events in Earth's history were likely caused by the "devastating" effects of nearby supernova explosions, a new study suggests.

Hall’s Cave, situated on the Edwards Plateau of central Texas, contains a well-dated latest Quaternary sedimentary sequence containing a high-resolution record of faunal, climatic, and geochemical changes.

<p xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="first" dir="auto" id="d4303035e127">In an article comprising some 96,000 words, <a class="xref-link" href="#r28">Holliday et al. (2023)</a> (HEA) claim to have “comprehensively refuted” the Younger Dryas impact hypothesis (YDIH), even though it has been corroborated by scores of articles in dozens of peer-reviewed journals based on the discovery of some combination of synchronous nanodiamonds, exotic microspherules and platinum enrichment at more than 50 Younger Dryas boundary sites on five continents. No hypothesis or theory is immune from criticism, but to “comprehensively refute” one so well established should require dispositive falsifying evidence. However, HEA provide no new evidence of their own and many of their arguments are based on faulty reasoning. Their remaining differences of opinion do not lend themselves to the falsification of an active hypothesis supported by an abundance of reproducible evidence, which now includes shocked quartz which is generally accepted to be produced only by cosmic impacts. Their article can therefore be called a Gish gallop; a long series of weak or flawed arguments designed to overwhelm an opponent. Since HEA’s claims are too many to respond to individually, we instead have selected portions of their article for critical analysis. By providing strong line-by-line counterarguments to their text we crucially show that they demonstrate a poor understanding of the logic required to test the YDIH and a poor understanding of uncertainty in experimental data analysis, and these problems propagate through many parts of their review. We also show that they repeatedly distort the facts and make misleading claims or derisory remarks. In summary, their approach is a corruption of the scientific method. In fact, the YDIH remains in a very strong position and probably represents a second example to go along with the Alvarez Theory of an extraterrestrial event that affected life on Earth. A hypothesis with such potential should not be so casually dismissed and instead should continue to be the subject of research. </p>

<p xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="first" dir="auto" id="d7946208e187">We studied a proposed impact site: the circular Smerdyachee Basin. This consists of Lake Smerdyachee in its center, which is ~255 m in diameter. The lake is surrounded by a continuous raised rim, ~409 m in diameter (range: 404–414 m). To the SE, we found a 3% Ni spherule inside a Ni-rich rock along with scattered angular Paleozoic rock fragments 10 to 30 cm in diameter. The latter appear only on one third of the rim and come from at least 40 m depth. These features – a continuous raised rim, Ni-bearing rocks, and asymmetrical excavation of basement rocks – are typically associated with impact craters. Modeling suggests the basin formed from the impact of an iron meteorite ~ 18 m wide that produced minimal shock melting or projectile vaporization. Fragments of a hypothetical iron meteorite should lie within a 179 by 126 m ellipse under Lake Smerdyachee. In the future, retrieval of projectile fragments and subsequent microprobe analyses of their composition would constitute more compelling evidence for an impact origin. </p>

In 1908, a force 1,000 times more powerful than the Hiroshima bomb detonated over the remote forests of Siberia, flattening 80 million trees across an area the size of a major city. But here's the part that keeps scientists up at night: there was no crater. Welcome to the podcast that reopens the case file on the Tunguska Event, one of history's most terrifying and profound unexplained phenomena. This isn't just a history lesson; it's a forensic investigation into a cosmic-level catastrophe. We'll present the mainstream scientific theory: a massive asteroid or comet that exploded in an atmospheric airburst, an event so powerful that modern simulations show it was more destructive than a surface-level nuclear blast. We'll sift through the chilling eyewitness testimonies—accounts of "fire in the sky," multiple suns, and the ground shaking hundreds of miles away. But then, we venture into the fringe. We’ll examine the wild and compelling alternative theories that the history books won't touch. Could it have been a miniature black hole passing through the Earth? Or something not of this world—a UFO malfunction? We present all the evidence, from seismic data discrepancies to the strange accounts that science still can't explain. If you're ready to journey into the heart of one of the greatest ancient mysteries, hit that subscribe button. Let's find out what really happened on that fateful morning in Siberia.

Buried deep in Greenland's ice sheet lies a puzzling chemical signature that has sparked intense scientific debate. A sharp spike in platinum concentrations, discovered in an ice core (a cylinder of ice drilled out of ice sheets and glaciers) and dated to around 12,800 years ago, has provided support for a hypothesis that Earth was struck by an exotic meteorite or comet at that time.

At Abu Hureyra (AH), Syria, the 12,800-year-old Younger D...