Four "potentially hazardous" space rocks, which are between 100 and 580 feet across, will all make their closest approaches to Earth within less than 12 hours of one another on Thursday (Oct. 24). Two of them were only discovered earlier this month.
A quartet of particularly hefty asteroids, including two that were discovered earlier this month and another that is as tall as a skyscraper, will make their closest approaches to Earth on Thursday (Oct. 24) — all within 12 hours of one another. The "potentially hazardous" space rocks will all get similarly close to our planet, but pose zero threat to life on Earth.

The first asteroid to make its closest approach will be 2015 HM1, also the smallest of the four space rocks at around 100 feet (30 meters) across. It will reach its closest point to our planet at around 4:36 a.m. UTC (0:36 a.m. EDT) when it reaches a minimum distance of 3.4 million miles (5.5 million kilometers) from us, according to NASA's Asteroid Watch dashboard. (That's roughly 14 times the average distance between Earth and the moon.)

The next visitor will be the roughly 170-foot-wide (52 m) space rock 2024 TP17, which will make its closest approach at around 8:20 a.m. UTC (4:20 a.m. EDT) and will get to within 2.9 million miles (4.7 million km) of our planet.

The final two asteroids — 2002 NV16 and 2024 TR6 — will make their closest approaches within just four minutes of each other. 2002 NV16, which is around 580 feet (177 m) across, making it the largest of the four, will reach a minimum distance of 2.8 million miles (4.5 million km) at around 15:47 p.m. UTC (11:47 a.m. EDT). It will be quickly followed by the 150-foot-wide (46 m) asteroid 2024 TR6, which will come within 3.5 million miles (5.6 million km) of Earth at 15:51 p.m. UTC (11:51 a.m. EDT).

New images of an asteroid impact crater buried deep below the floor of the Atlantic Ocean have been published today by researchers at Heriot-Watt University.

The images confirm the 9km Nadir Crater, located 300m under the floor of the Atlantic Ocean, was caused by an asteroid smashing into Earth at the end of the Cretaceous period around 66 million years ago.

That's the same age as the dinosaur-killing 200 km wide, Chicxulub impact crater in Mexico.

There are around 20 confirmed marine craters worldwide, and none of them has been captured in anything close to this level of detail.

Dr Uisdean Nicholson

The images have helped the researchers determine what happened in the minutes following impact: the formation of an initial bowl-shaped crater, rocks turned to a fluid-like state and flowing upwards to the crater floor, the creation of a damage zone covering thousands of square kilometres beyond the crater, and an 800-metre-plus high tsunami that would have travelled across the Atlantic ocean.

The findings are reported in Nature Communications Earth & Environment.

Astronomers are monitoring a new comet discovered just a few days ago by the ATLAS survey. It's so new, it doesn't have a name yet. Provisionally designated "A11bP7I," the comet appears to be a relatively large sungrazer on course to become a bright naked-eye object in late October. Dennis Möller, Michael Jäger and Gerald Rhemann photographed the new discovery last night in Namibia:
"We are here in Namibia to observe Comet Tsuchinshan-ATLAS," says Jäger. "The new sungrazing comet was discovered not far away, so we took a look. It is already 11th mag with a 2' green coma and a short tail."

The orbit and brightness of A11bP7I remind experts of Comet Lovejoy (C/2011 W3), a sungrazer that flew through the sun's atmosphere in Dec. 2011. Comet Lovejoy emerged from the close encounter intact and put on a spectacular show for amateur astronomers during the Christmas holidays of that year.

Up to 60% of near-Earth objects could be dark comets, mysterious asteroids that orbit the sun in our solar system that likely contain or previously contained ice and could have been one route for delivering water to Earth, according to a University of Michigan study.

The findings suggest that asteroids in the asteroid belt, a region of the solar system roughly between Jupiter and Mars that contains much of the system's rocky asteroids, have subsurface ice, something that has been suspected since the 1980s, according to Aster Taylor, U-M graduate student in astronomy and lead author of the study.

The study also shows a potential pathway for delivering ice into the near-Earth solar system, Taylor says. How Earth got its water is a longstanding question.

"We don't know if these dark comets delivered water to Earth. We can't say that. But we can say that there is still debate over how exactly the Earth's water got here," Taylor said. "The work we've done has shown that this is another pathway to get ice from somewhere in the rest of the solar system to the Earth's environment."

The research further suggests that one large object may come from the Jupiter-family comets, comets whose orbits take them close to the planet Jupiter. The team's results are published in the journal Icarus.

Researchers continue to expand the case for the Younger Dryas Impact hypothesis. The idea proposes that a fragmented comet smashed into the Earth's atmosphere 12,800 years ago, causing a widespread climatic shift that, among other things, led to the abrupt reversal of the Earth's warming trend and into an anomalous near-glacial period called the Younger Dryas.

Now, UC Santa Barbara emeritus professor James Kennett and colleagues report the presence of proxies associated with the cosmic airburst distributed over several separate sites in the eastern United States (New Jersey, Maryland and South Carolina), materials indicative of the force and temperature involved in such an event, including platinum, microspherules, meltglass and shock-fractured quartz. The study appears in ScienceOpen's journal Airbursts and Cratering.

"What we've found is that the pressures and temperatures were not characteristic of major crater-forming impacts but were consistent with so-called 'touchdown' airbursts that don't form much in the way of craters," Kennett said.

If you wanted evidence that a giant comet wiped out the wooly mammoth, you might look for a giant crater.

But so far, you'd be out of luck.

"Some of our critics have said, 'Where's the crater?'" says Christopher Moore, an archaeologist at the University of South Carolina. "As of now, we don't have a crater or craters."

But Moore says that by looking below the surface, you can find strong evidence for the Younger-Dryas impact hypothesis, which states that large comet fragments hit Earth or exploded in the atmosphere shortly after the last ice age, setting off cataclysmic changes in the environment, crater or not.

Lately we have been having a lot of meteor activity over the Iberian Peninsula, a phenomenon that causes great expectation.

As you will remember, on March 29 we had two bolides over the eastern part of Spain, which generated many comments.

Tonight, around 0:46 CET (23:46 Lisbon time), a bright fireball has illuminated the skies of Spain and Portugal. According to the Civil Protection of Portugal, the meteor would have fallen in the village of Pereira, in Castro Daire, northern Portugal, 60 km southwest of Porto. Portugal declared an alert and mobilized its firefighters in case there was any information.

Here we can see an impressive video recorded by @rvbzzx in Lisbon and slowed down by @jpunto88_ to make it look better:

A paper published in March of 2021 in the journal Science Advances reports on the discovery of evidence for a large airburst type impact within the SØr Rondane Mountains, Queen Maud Land, East Antarctica. The report bears the names of a 15-member international team that did the research. The lead author was M. Van Ginneken with the Belgian Geological Survey. In the first sentence of the abstract to the article the authors support something I have been saying for literally decades: "Large airbursts, the most frequent hazardous impact events, are estimated to occur orders of magnitude more frequently than crater-forming impacts."

This fact is confirmed simply because airbursts don't leave impact craters. In this case the fingerprints of the event took the form of condensation spherules resulting from "a touchdown event, in which a projectile vapor jet interacts with the Antarctic ice sheet." The authors go on to explain that "Finding evidence of these low-altitude meteoritic events thus remains critical to understanding the impact history of Earth and estimating hazardous effects of asteroid impacts." They further report that "In recent years, meteoritic ablation debris resulting from airburst events have been found in three different locations of Antarctica. The material . . . all appears to have been produced during a Tunguska-like airburst event 480 thousand years (ka) ago."

With respect to their research, they say: "Here, we present the discovery of extraterrestrial particles formed during a significantly larger event recovered on . . . Queen Maud Land, East Antarctica. The characteristic features of the recovered particles attest to an unusual type of touchdown event, intermediate between an airburst and a crater-forming impact, during which the high-velocity vapor jet produced by the total disruption of an asteroid reached the Antarctic ice sheet." This event was estimated by the team to have occurred about 430 thousand years ago.

The authors provide some critical perspective on the effects of these type of impacts:

"The impact hazards resulting form the atmospheric entry of an asteroid that are currently being addressed by impact mitigation programs depend mainly on whether the impactor reaches the ground or is entirely disrupted in the atmosphere (i.e., airburst). For small-to medium-sized impactors (50- to 150-m diameter) producing airbursts, the main hazard is limited to blast effects resulting in strong overpressures over areas of up to 100,000 km2 wide. [38,600 sq miles] Thermal radiation may also result in fires over an area of 10 to 1000 km2 wide. . . . in addition to shockwaves and thermal radiation covering the aforementioned areas, these events are potentially destructive over a large area, corresponding to the area of interaction between the hot jet and the ground. The authors point out that such an event over Antarctica would inject ice crystals and impact dust into the upper atmosphere but would not directly affect human activity. However, they explain that "if a touchdown impact event takes place above a densely populated area, this would result in millions of casualties and severe damages over distances of up to hundreds of kilometers."

Now comes a new report in Earth and Planetary Science Letters on the discovery of evidence for yet another airburst event over Antarctica. The 11-member team responsible for the report is comprised of geologists, astrophysicists, and archaeologists from the U.S., the United Kingdom, Belgium, Russia, Japan, France and Italy.

Suddenly, amateur astronomers are seeing a naked-eye comet in the evening sky. It's Comet 12P/Pons-Brooks, also known as the 'devil comet'. Waiting for next Monday's solar eclipse in Mexico, Petr Horálek photographed the comet last night and found it much brighter than the last time he saw it:

"I assume an outburst is in progress," says Horálek. "My estimate of the comet's magnitude is +3.5. Definitely worth taking a look in the next hours and days."

Indeed, now is a good time to look. After sunset, the comet emerges in the western sky not far from the planet Jupiter. Naked-eye observers will see a dim fuzzball. Cameras and small telescopes reveal the comet's magnificent tail.

Mainstream science has done its best to debunk the notion, but a belief in a world-changing series of prehistoric impacts continues to gain momentum.
In 2007, a group of researchers, led by a nuclear physicist named Richard Firestone, announced an astonishing discovery. They had uncovered evidence, they said, that 12,900 years ago, a comet — or possibly a whole fleet of comets — struck Earth and changed the course of history. For the preceding two and a half million years, through the Pleistocene Epoch, the planet's climate fluctuated between frozen stretches, called glacials, and warm interglacials. At that time, Earth was warming again, and the ice sheets that covered much of North America, Europe and Asia were in retreat. Mammoths, steppe bison, wild horses and other enormous mammals still wandered the Americas, pursued by bands of humans wielding spears with fluted stone blades. Suddenly, somewhere over the Upper Midwest — an explosion.

Presenting their claim in the Proceedings of the National Academy of Sciences, a top scientific journal, the researchers took the sober tone characteristic of such publications. But in The Cycle of Cosmic Catastrophes, a book published around the same time, two of the researchers described the scene more vividly. The impact caused the ground to shake and the sky to glow, they wrote. A hail of tiny molten particles sank into flesh and set forests ablaze. Soot blotted out the sun. Earth's magnetic field wavered, and living things were bombarded by cosmic rays, confounding the navigational senses of turtles and porpoises, which beached themselves en masse. Addled birds plummeted from the sky.

Most disastrous of all, the impact shattered the ice dam holding back Lake Agassiz, a vast expanse of glacial meltwater that stretched across Manitoba, Ontario, Saskatchewan, Wisconsin and Minnesota. The lake cascaded into the Atlantic Ocean, where the freshwater pooled over the denser seawater, disrupting the convection current carrying warm water north from the tropics. The Northern Hemisphere plunged back into full-glacial cold.

For decades, scientists had puzzled over the cause of this rapid climatic reversal, which they marked by, among other things, the reappearance in southerly fossil deposits of tundra plants. These included the wildflower Dryas integrifolia, which gives the 1,200-year time span its name: the Younger Dryas. Here was an explanation: The impact caused the sudden cooling, the Firestone team argued, and contributed to the demise of the mammoths, steppe bison and other large Pleistocene mammals, along with the people who pursued them.