Dinosaurs extinct by asteroid, how?


This 2016 video says about itself:

Here’s a look at what might have caused the extinction of dinosaurs approximately 65 million years ago.

From Imperial College London in England:

Dinosaur-dooming asteroid struck Earth at ‘deadliest possible’ angle

May 26, 2020

New simulations from Imperial College London have revealed the asteroid that doomed the dinosaurs struck Earth at the ‘deadliest possible’ angle.

The simulations show that the asteroid hit Earth at an angle of about 60 degrees, which maximised the amount of climate-changing gases thrust into the upper atmosphere.

Such a strike likely unleashed billions of tonnes of sulphur, blocking the sun and triggering the nuclear winter that killed the dinosaurs and 75 per cent of life on Earth 66 million years ago.

Drawn from a combination of 3D numerical impact simulations and geophysical data from the site of the impact, the new models are the first-ever fully 3D simulations to reproduce the whole event — from the initial impact to the moment the final crater, now known as Chicxulub, was formed.

The simulations were performed on the Science and Technology Facilities Council (STFC) DiRAC High Performance Computing Facility.

Lead researcher Professor Gareth Collins, of Imperial’s Department of Earth Science and Engineering, said: “For the dinosaurs, the worst-case scenario is exactly what happened. The asteroid strike unleashed an incredible amount of climate-changing gases into the atmosphere, triggering a chain of events that led to the extinction of the dinosaurs. This was likely worsened by the fact that it struck at one of the deadliest possible angles.

“Our simulations provide compelling evidence that the asteroid struck at a steep angle, perhaps 60 degrees above the horizon, and approached its target from the north-east. We know that this was among the worst-case scenarios for the lethality on impact, because it put more hazardous debris into the upper atmosphere and scattered it everywhere — the very thing that led to a nuclear winter.”

The results are published today in Nature Communications.

Crater creation

The upper layers of earth around the Chicxulub crater in present-day Mexico contain high amounts of water as well as porous carbonate and evaporite rocks. When heated and disturbed by the impact, these rocks would have decomposed, flinging vast amounts of carbon dioxide, sulphur and water vapour into the atmosphere.

The sulphur would have been particularly hazardous as it rapidly forms aerosols — tiny particles that would have blocked the sun’s rays, halting photosynthesis in plants and rapidly cooling the climate. This eventually contributed to the mass extinction event that killed 75 per cent of life on Earth.

The team of researchers from Imperial, the University of Freiburg, and The University of Texas at Austin, examined the shape and subsurface structure of the crater using geophysical data to feed into the simulations that helped diagnose the impact angle and direction. Their analysis was also informed by recent results from drilling into the 200 km-wide crater, which brought up rocks containing evidence of the extreme forces generated by the impact.

Peak performance

Pivotal to diagnosing the angle and direction of impact was the relationship between the centre of the crater, the centre of the peak ring — a ring of mountains made of heavily fractured rock inside the crater rim — and the centre of dense uplifted mantle rocks, some 30 km beneath the crater.

At Chicxulub, these centres are aligned in a southwest-northeast direction, with the crater centre in between the peak-ring and mantle-uplift centres. The team’s 3D Chicxulub crater simulations at an angle of 60 degrees reproduced these observations almost exactly.

The simulations reconstructed the crater formation in unprecedented detail and give us more clues as to how the largest craters on Earth are formed. Previous fully 3D simulations of the Chicxulub impact have covered only the early stages of impact, which include the production of a deep bowl-shaped hole in the crust known as the transient crater and the expulsion of rocks, water and sediment into the atmosphere.

These simulations are the first to continue beyond this intermediate point in the formation of the crater and reproduce the final stage of the crater’s formation, in which the transient crater collapses to form the final structure. This allowed the researchers to make the first comparison between 3D Chicxulub crater simulations and the present-day structure of the crater revealed by geophysical data.

Co-author Dr Auriol Rae of the University of Freiburg said: “Despite being buried beneath nearly a kilometre of sedimentary rocks, it is remarkable that geophysical data reveals so much about the crater structure — enough to describe the direction and angle of the impact.”

The researchers say that while the study has given us important insights into the dinosaur-dooming impact, it also helps us understand how large craters on other planets form.

Co-author Dr Thomas Davison, also of Imperial’s Department of Earth Science and Engineering, said: “Large craters like Chicxulub are formed in a matter of minutes, and involve a spectacular rebound of rock beneath the crater. Our findings could help advance our understanding of how this rebound can be used to diagnose details of the impacting asteroid.”

The work was supported by the International Ocean Discovery Program (IODP), International Continental Scientific Drilling Program (ICDP), (STFC) DiRAC High Performance Computing Facility and the Natural Environment Research Council.

Coronavirus, militarism and astronomy


This 10 April 2020 video says about itself:

Coronavirus: How the Arms Trade is Making You Sick | Andrew Feinstein

The story of how a trillion-dollar fighter jet that never worked helped place you in danger

A year after the first black hole image, the EHT has been stymied by the coronavirus. With this year’s observing run canceled due to the coronavirus, the Event Horizon Telescope team is analyzing data from 2017 and 2018. By Lisa Grossman, April 10, 2020.

Trump wants corporate privatisation of space


This 2015 video says about itself:

The Wonders of Space – Amazing Hubble interstellar images – sit back, relax and enjoy the view

Images from Hubble, Spitzer, Herschel and Chandra Telescopes as well as from the ISS.

After President Donald Trump tried to buy Greenland with United States taxpayers’ money … he now tries with outer space.

By Don Barrett in the USA:

Trump executive order asserts US property rights in outer space

10 April 2020

President Donald Trump signed an executive order Monday, “Encouraging International Support for the Recovery and Use of Space Resources”, that asserts US property rights in outer space. Throwing aside decades of international negotiations, it declares that “the United States does not view it [space] as a global commons”, and that “[s]uccessful long-term exploration … will require partnership with commercial entities to recover and use resources”, and these will require “the right to commercial recovery”.

The Trump administration’s order follows its December creation of a new “Space Force” branch of the US military, but this is not uniquely a phenomenon of this administration. Last summer, France’s Macron administration announced its own space command, and programs to weaponize space were previously touted by both the US administrations of Reagan and George W. Bush. Bush’s report explicitly made a connection to the early days of empire, comparing the militarization of space with the early development of navies, and the necessity to achieve “full-spectrum dominance” in space, land, sea and air.

From the time of the Age of Exploration, new achievements in technology and the productive forces have opened new frontiers to scientific discovery—and to the scramble for profitable returns. Outer space is now simply the latest of these frontiers in which US imperialism expects future advantage, and to attain it is prepared to assert and defend its strategic interests.

Both the assertion of commercial interests in and the militarization of space directly flout international agreements built up over the post-World War II period. The idea of international governance, as a means to suspend for a time the scrambling over frontiers not yet ripe for exploitation, was first applied in the Antarctic Treaty System, which entered force in 1961. Antarctica was declared a scientific preserve, with freedom of scientific exploration but with military activity banned.

The Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies (the “Outer Space Treaty”) emulated the Antarctic agreement, forbidding weapons of mass destruction in space and reserving the use of celestial bodies to peaceful purposes.

Articles I and II of the treaty specifically state, “The exploration and use of outer space, including the moon and other celestial bodies, shall be carried out for the benefit and in the interests of all countries … and shall be the province of all mankind,” and that “outer space, including the Moon and other celestial bodies, is not subject to national appropriation by claim of sovereignty.”

A further treaty, the “Agreement Governing the Activities of States on the Moon and Other Celestial Bodies” (the “Moon Treaty”) of 1979, extends this concept to declare, “Neither the surface nor the subsurface of the moon, nor any part thereof or natural resources in place, shall become property of any State, international intergovernmental or non-governmental organization, national organization or non-governmental entity or of any natural person.”

The 1979 treaty, negotiated at a period when international divisions were rapidly intensifying, failed to gain any spacefaring nations’ signatures, and among the great powers only France signed.

And even with these treaties, Earth orbit was rapidly filled with surveillance satellites, nuclear radio-isotope power supplies, and even several high-powered military satellites powered by full-blown nuclear reactors, subject to eventually reentering and polluting the Earth, as one already has.

By 2015, the grubbing for profit was asserted openly in the US “Commercial Space Launch Competitiveness Act of 2015,” which passed the US House by 281–133, with nearly all Republicans and 48 Democrats voting in favor. It was affirmed by unanimous consent in the Senate and signed into law by Democratic President Barack Obama. While the act claims it does not “assert sovereignty, or sovereign or exclusive rights,” it grants a commercial operator the right to be “entitled to any asteroid resource or space resource obtained, including to possess, own, transport, use, and sell.”

The latest executive order goes further. Trump has directed the Secretary of State to object to any efforts to represent the 1979 Moon Treaty as customary international law. “This Agreement [the 1979 treaty] represents a failed attempt at constraining free enterprise…” Furthermore, the administration stated that it will “negotiate joint statements, bilateral and multi-lateral agreements … with like-minded states.” One can already see the “no trespassing” signs.

The Trump executive order was immediately criticized by the Russian space agency Roscosmos, which noted, “Attempts to expropriate outer space and aggressive plans to actually seize territories of other planets hardly set the countries [towards the goal of] fruitful cooperation.”

A driver for the division of space is the rapidly dropping cost to reach it. From the first US satellite launch in 1957, the price has dropped a hundredfold, from $1,000,000 to $10,000 per kilogram by 1970, where it remained for thirty years. But efficient and reusable new technologies now promise launch costs in the relatively near future under $2000 per kilogram, and within a few decades, under $200 per kilogram.

Something of a gold rush is underway to set down stakes and interests, years before expected returns. In fact, the last US landing of any spacecraft, manned or unmanned, on the moon was in 1972. Meanwhile, nation after nation is entering or reentering the race, with China having landed four unmanned probes on the moon, including the first on the “far” side, never directly visible from Earth because of the moon’s tidally-locked orbit.

One reality that will not change is that the surface of the Earth remains in a deep gravity well, which even with newly affordable launch costs will remain an expensive source of raw materials from which to develop facilities in space. Long-term, bulk supplies for building stations, fueling vehicles, and providing water and oxygen to inhabitants, are best provided from asteroids or potential resources on the lunar surface—including in particular the water ice that is thought to exist in the cold perpetually-shadowed regions of its polar craters.

In the language of rocketry, the “delta-v,” the fuel-consuming velocity shift which a rocket requires to accomplish a certain mission, is far smaller from the surface of the moon, and even smaller from certain asteroids, to Earth orbit than from the surface of the Earth. This is why the Apollo lunar lander was so much smaller to return astronauts from the lunar surface than the vast Saturn V launch vehicle necessary to set them on their way. And establishing priority, especially for potentially limited good mining locations for lunar ice, or for asteroids on a rare trajectory that permits Earth-orbit capture with minimal cost in resources, is driving the stake-building.

The potential benefits to humanity, as anticipated in the UN treaties, are vast. But under capitalism and its associated nation-state system, every advance is also simultaneously turned into a tool of class oppression and national advantage. With the partition of space comes its militarization, and the provisioning of resources to unlock new explorations also enables populating Earth orbit with new weapons and more complete surveillance directed below, and drawing the inevitable national boundaries on the moon.

Dwarf planet Pluto, has it an ocean?


This 24 May 2019 video says about itself:

Pluto might seem like the least likely place to find liquid water, but thanks to New Horizons, we have new information about oceans on the dwarf planet and more from the outer reaches of the solar system!

By Lisa Grossman, 27 March 2020:

If Pluto has a subsurface ocean, it may be old and deep

New research hints that liquid water might be common at the solar system’s edge

A suspected subsurface ocean on Pluto might be old and deep.

New analyses of images from NASA’s New Horizons spacecraft suggest that the dwarf planet has had an underground ocean since shortly after Pluto formed 4.5 billion years ago, and that the ocean may surround and interact with the rocky core.

If so, oceans could be common at the solar system’s edge — and may even be able to support life. That possibly “transforms the way we think about the Kuiper Belt”, the region of icy objects beyond the orbit of Neptune (SN: 3/27/19), says planetary scientist Adeene Denton of Purdue University in West Lafayette, Ind.

On its pass through the Kuiper Belt in 2015, New Horizons revealed that despite the dwarf planet’s location nearly 6 billion kilometers from the sun, Pluto showed signs of hosting an ocean of liquid water beneath an icy shell (SN: 9/23/16).

How much liquid may lie beneath Pluto’s ground, how long it’s been there, and how much the water may have partially frozen over time is hard to tell from the surface. The new research, which had been scheduled for presentation the week of March 16 at the canceled Lunar and Planetary Science Conference in The Woodlands, Texas, has dug into those questions.

“If there’s an ocean today, it raises the question of, when did that ocean get there?” says planetary scientist Carver Bierson of the University of California, Santa Cruz.

Bierson considered two possible histories for Pluto’s potential ocean. If the dwarf planet had a “cold start,” any subsurface water would first have been frozen before melting under heat from decaying radioactive elements in the dwarf planet’s core, only to partially freeze again over time. In that scenario, Bierson expected to see cracks and ripples across Pluto’s icy shell from the orb’s contraction as the ice melted and then expansion as water refroze. Contracting would make the ice crumple into mountainlike features, while expanding would stretch the ice and create faults and graben.

Bierson’s second scenario envisioned a “warm start” for Pluto, where the ocean would have been liquid for nearly all of Pluto’s 4.5-billion-year existence. In that case, the surface would show only cracks from the sea expanding as it partially froze. And that’s exactly what Bierson and colleagues found in New Horizon’s images, suggesting that Pluto’s liquid ocean is nearly as old as the dwarf planet itself.

“That means maybe Pluto did start off warm,” Bierson says. “Maybe it started with a liquid ocean really early on.”

In a separate study, Denton and colleagues considered the impact that formed Sputnik Planitia, the left lobe of Pluto’s distinctive heart-shaped basin. Because of how New Horizons flew past Pluto, scientists’ view of half the dwarf planet is fuzzy. But the team was able to see lines on Pluto’s surface on the exact opposite side of the globe from Sputnik Planitia, the researchers reported in October 2019 at arXiv.org. Those lines might be the imprints of shock waves from a massive impact that formed the enormous basin, Denton says.

“If the impact is large enough … the planet itself can act like a lens, and focus the wave energy at the exact opposite point on the planet from the impact,” she says.

Pluto’s internal structure would have controlled how those shock waves shuddered through the dwarf planet. Looking at the cracks in the surface ice could give clues to the thickness of the proposed ocean or the core’s chemical makeup. So Denton and her colleagues ran computer simulations of an impact to look for clues.

“We got the fun answer,” she says. To explain the lines seen on the dwarf planet, not only would Pluto need a large ocean, 150 kilometers or more in thickness, but the core must contain minerals, such as serpentine, that form through interactions between rock and water. Astrobiologists think that water-rock interactions could provide energy and nutrients for life (SN: 5/19/15). The possibility of a somewhat soggy core could let life get a toehold at the fringes of the solar system, Denton says.

“It’s certainly not exactly a smoking gun,” she says. “But it’s exciting.”

The possibility that Pluto has a habitable ocean raises the odds that other Kuiper Belt objects do too, says planetary scientist James Tuttle Keene of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., who is a member of the New Horizons team but was not involved in either study.

“This lays out one of the coolest hypotheses that a future Pluto mission could test,” he says. “If Pluto can have an ocean and potentially be habitable, it’s very likely that other bodies in the Kuiper Belt also are ocean worlds and also are potentially habitable.”

Astronomers have found the edge of the Milky Way at last. Our galaxy spans 1.9 million light-years, a new study finds: here.

‘Star Betelgeuse dusty, not about to explode’


This 29 February 2020 video says about itself:

At the beginning of 2020, the world held its collective breath as a nearby behemoth star, called Betelgeuse, start to dramatically fade. Could this mean the star is about to go supernova? With the recent flutter of news activity settling down, we are now finally starting to understand what might have really happened. Today, we take a deep dive into what makes massive stars like this tick, and then get into how we might have now finally come up with answers to this bizarre event.

An educational video written and presented by Prof. David Kipping.

Chapters 0:00 Teaser 0:53 Massive Stars 7:07 Dying Massive Stars 12:47 Dimming 2020 17:36 Explaining the Dimming

By Lisa Grossman today:

The star Betelgeuse might just be dusty, not about to explode

The red supergiant’s time doesn’t appear to be nigh after all

Betelgeuse, one of the brightest stars in the sky, suddenly faded in late 2019, startling astronomers and prompting speculation that the star was about to explode.

But by the end of February, Betelgeuse had started to brighten again, quashing rumors of its demise. Now a study suggests that the dimming was due to dust recently shed by the star.

“I think some people wanted this to be seen as the death throes of the star, and it’s very much not,” says astrophysicist Emily Levesque of the University of Washington in Seattle.

Betelgeuse, a type of massive, elderly star called a red supergiant, lies about 700 light-years away from Earth and marks the shoulder of the constellation Orion. Astronomers have known for decades that, someday soon, the star is going to run out of fuel and detonate in a brilliant supernova (SN: 2/8/17).

So when the star began dimming in October 2019, astronomers took notice. By December 23, it had slipped from the sixth or seventh brightest star in the sky to the 21st. That didn’t necessarily mean an explosion was imminent, but any strange behavior in a red supergiant is worth watching, Levesque says.

“When people think about stars that are visible in our sky that could explode soon, Betelgeuse is near the top of the list,” she says. “So when people said this star is doing something weird, it caught people’s attention.”

Levesque and astronomer Philip Massey of the Lowell Observatory in Flagstaff, Ariz., decided to investigate more mundane possibilities than an imminent supernova that could explain the dimming. Those options include the star’s surface cooling off suddenly, as boiling blobs of plasma rise and sink within it (SN: 1/29/20), or a cloud of dust recently puffing off the star, temporarily obscuring starlight and making Betelgeuse appear dimmer than it really is.

The pair observed the star on February 14 — when it was nearly at its dimmest — looking for signs of titanium oxide molecules in the star’s outer layers, a clue to its temperature. Comparing those observations with similar ones that Levesque had taken in 2004 showed that the temperature had dropped by about a measly 25 degrees Celsius.

“To our surprise, Betelgeuse didn’t look that different,” Levesque says. “The temperature couldn’t explain how much dimmer Betelgeuse had gotten in the last few months.”

That leaves the dust explanation, the scientists report in a study to appear in the Astrophysical Journal Letters. “It’s partly process of elimination,” Levesque says. Red supergiants like Betelgeuse are known to puff out clouds of gas which condense into dust. And the star did dim uniformly over all wavelengths of light that Levesque measured, which supports the idea that dust from the star is to blame. By contrast, dust that lies in the spaces between stars would block certain wavelengths of light more than others.

The study “is a first step to a better understanding of what is happening to Betelgeuse,” says astrophysicist Miguel Montargès of KU Leuven in Belgium, who wasn’t involved in the research.

Montargès and colleagues have observed Betelgeuse with the Very Large Telescope in Chile. The star looked markedly dimmer in December 2019 than it did when the telescope observed it in January 2019, before the fade-out began. But the dimming seemed to appear only in the star’s southern hemisphere, not uniformly across Betelgeuse, according to an image the team released February 14. That could be explained by an asymmetrical dust cloud, although the situation may be more complicated. Montargès plans to observe Betelgeuse again the week of March 16 and publish the results later this year.

If the dimming is due to dust, that will give astronomers an opportunity to watch a nearby star losing mass in real-time. “There’s that famous quote, we are stardust,” Montargès says, paraphrasing a line spoken by the late astrophysicist Carl Sagan. “Perhaps the atoms we are looking at will one day be part of a planet, and perhaps sentient beings. That’s why it’s really exciting.”

Other astronomers are holding out for more information. “The dust model is viable, but it also doesn’t rule out changes in the star itself,” says astronomer Edward Guinan of Villanova University in Pennsylvania, who has also been observing Betelgeuse since the fall. Betelgeuse naturally dims and brightens on a 420-day cycle, and although the dimming is not usually this extreme, it could still be nothing out of the ordinary. “I think the jury is still out.”

Dinosaur age days were shorter, mollusks show


This 1 July 2016 video from England says about itself:

New insights for the rudist phylogeny (Bivalvia, Hippuritida)

By Valentin Rineau.

Recorded at Progressive Palaeontology 2016, Oxford.

From the American Geophysical Union in the USA:

Ancient shell shows days were half-hour shorter 70 million years ago

Beer stein-shaped distant relative of modern clams captured snapshots of hot days in the late Cretaceous

March 9, 2020

Earth turned faster at the end of the time of the dinosaurs than it does today, rotating 372 times a year, compared to the current 365, according to a new study of fossil mollusk shells from the late Cretaceous. This means a day lasted only 23 and a half hours, according to the new study in AGU’s journal Paleoceanography and Paleoclimatology.

The ancient mollusk, from an extinct and wildly diverse group known as rudist clams, grew fast, laying down daily growth rings. The new study used lasers to sample minute slices of shell and count the growth rings more accurately than human researchers with microscopes.

The growth rings allowed the researchers to determine the number of days in a year and more accurately calculate the length of a day 70 million years ago. The new measurement informs models of how the Moon formed and how close to Earth it has been over the 4.5-billion-year history of the Earth-Moon gravitational dance.

The new study also found corroborating evidence that the mollusks harbored photosynthetic symbionts that may have fueled reef-building on the scale of modern-day corals.

The high resolution obtained in the new study combined with the fast growth rate of the ancient bivalves revealed unprecedented detail about how the animal lived and the water conditions it grew in, down to a fraction of a day.

“We have about four to five datapoints per day, and this is something that you almost never get in geological history. We can basically look at a day 70 million years ago. It’s pretty amazing,” said Niels de Winter, an analytical geochemist at Vrije Universiteit Brussel and the lead author of the new study.

Climate reconstructions of the deep past typically describe long term changes that occur on the scale of tens of thousands of years. Studies like this one give a glimpse of change on the timescale of living things and have the potential to bridge the gap between climate and weather models.

Chemical analysis of the shell indicates ocean temperatures were warmer in the Late Cretaceous than previously appreciated, reaching 40 degrees Celsius (104 degrees Fahrenheit) in summer and exceeding 30 degrees Celsius (86 degrees Fahrenheit) in winter. The summer high temperatures likely approached the physiological limits for mollusks, de Winter said.

“The high fidelity of this data-set has allowed the authors to draw two particularly interesting inferences that help to sharpen our understanding of both Cretaceous astrochronology and rudist palaeobiology,” said Peter Skelton, a retired lecturer of palaeobiology at The Open University and a rudist expert unaffiliated with the new study.

Ancient reef-builders

The new study analyzed a single individual that lived for over nine years in a shallow seabed in the tropics — a location which is now, 70-million-years later, dry land in the mountains of Oman.

Torreites sanchezi mollusks look like tall pint glasses with lids shaped like bear claw pastries. The ancient mollusks had two shells, or valves, that met in a hinge, like asymmetrical clams, and grew in dense reefs, like modern oysters. They thrived in water several degrees warmer worldwide than modern oceans.

In the late Cretaceous, rudists like T. sanchezi dominated the reef-building niche in tropical waters around the world, filling the role held by corals today. They disappeared in the same event that killed the non-avian dinosaurs 66 million years ago.

“Rudists are quite special bivalves. There’s nothing like it living today,” de Winter said. “In the late Cretaceous especially, worldwide most of the reef builders are these bivalves. So they really took on the ecosystem building role that the corals have nowadays.”

The new method focused a laser on small bits of shell, making holes 10 micrometers in diameter, or about as wide as a red blood cell. Trace elements in these tiny samples reveal information about the temperature and chemistry of the water at the time the shell formed. The analysis provided accurate measurements of the width and number of daily growth rings as well as seasonal patterns. The researchers used seasonal variations in the fossilized shell to identify years.

The new study found the composition of the shell changed more over the course of a day than over seasons, or with the cycles of ocean tides. The fine-scale resolution of the daily layers shows the shell grew much faster during the day than at night

“This bivalve had a very strong dependence on this daily cycle, which suggests that it had photosymbionts,” de Winter said. “You have the day-night rhythm of the light being recorded in the shell.”

This result suggests daylight was more important to the lifestyle of the ancient mollusk than might be expected if it fed itself primarily by filtering food from the water, like modern-day clams and oysters, according to the authors. De Winter said the mollusks likely had a relationship with an indwelling symbiotic species that fed on sunlight, similar to living giant clams, which harbor symbiotic algae.

“Until now, all published arguments for photosymbiosis in rudists have been essentially speculative, based on merely suggestive morphological traits, and in some cases were demonstrably erroneous. This paper is the first to provide convincing evidence in favor of the hypothesis,” Skelton said, but cautioned that the new study’s conclusion was specific to Torreites and could not be generalized to other rudists.

Moon retreat

De Winter’s careful count of the number of daily layers found 372 for each yearly interval. This was not a surprise, because scientists know days were shorter in the past. The result is, however, the most accurate now available for the late Cretaceous, and has a surprising application to modeling the evolution of the Earth-Moon system.

The length of a year has been constant over Earth’s history, because Earth’s orbit around the Sun does not change. But the number of days within a year has been shortening over time because days have been growing longer. The length of a day has been growing steadily longer as friction from ocean tides, caused by the Moon’s gravity, slows Earth’s rotation.

The pull of the tides accelerates the Moon a little in its orbit, so as Earth’s spin slows, the Moon moves farther away. The moon is pulling away from Earth at 3.82 centimeters (1.5 inches) per year. Precise laser measurements of distance to the Moon from Earth have demonstrated this increasing distance since the Apollo program left helpful reflectors on the Moon’s surface.

But scientists conclude the Moon could not have been receding at this rate throughout its history, because projecting its progress linearly back in time would put the Moon inside the Earth only 1.4 billion years ago. Scientists know from other evidence that the Moon has been with us much longer, most likely coalescing in the wake of a massive collision early in Earth’s history, over 4.5 billion years ago. So the Moon’s rate of retreat has changed over time, and information from the past, like a year in the life of an ancient clam, helps researchers reconstruct that history and model of the formation of the moon.

Because in the history of the Moon, 70 million years is a blink in time, de Winter and his colleagues hope to apply their new method to older fossils and catch snapshots of days even deeper in time.

Ophiuchus galaxy, universe’s biggest ever explosion


This 27 February 2020 video says about itself:

The biggest explosion seen in the universe has been found. This record-breaking, gargantuan eruption came from a black hole in a distant galaxy cluster hundreds of millions of light-years away.

Astronomers made this record-breaking discovery using X-ray data from NASA’s Chandra X-ray Observatory and ESA‘s XMM-Newton, and radio data from the Murchison Widefield Array in Australia and the Giant Metrewave Radio Telescope in India.

The unrivaled outburst was detected in the Ophiuchus galaxy cluster, which is about 390 million light-years from Earth. Galaxy clusters are the largest structures in the Universe held together by gravity, containing thousands of individual galaxies, dark matter, and hot gas.

In the center of the Ophiuchus cluster, there is a large galaxy that contains a supermassive black hole. Researchers have traced the likely source of this gigantic eruption to this black hole.

Although black holes are famous for pulling material toward them, they often expel prodigious amounts of material and energy. This happens when matter falling toward the black hole is redirected into jets, or beams, that blast outward into space and slam into any surrounding material.

Astronomers needed to combine the X-ray information along with the radio data in order to clinch this finding. They discovered that a cavity in the hot gas, first seen in Chandra data in 2016, was filled almost perfectly with radio emission created by electrons that had been accelerated to nearly the speed of light. This allowed them to confirm that an explosion of unprecedented size took place in Ophiuchus.

The amount of energy required to create the cavity in Ophiuchus is about five times greater than the previous record-holder, MS 0735+74, and hundreds and thousands of times greater than typical clusters.

The black hole eruption must have finished because the researchers do not see any evidence for current jets in the radio data. This shutdown can be explained by the Chandra data, which show that the densest and coolest gas seen in X-rays is currently located at a different position from the central galaxy. If this gas shifted away from the galaxy it will have deprived the black hole of fuel for its growth, turning off the jets.

While much has been learned about the galaxy cluster Ophiuchus through X-ray and radio telescopes, more data will be needed to answer the many remaining questions this object poses.

Earth has very small second moon


This 26 February 2020 video says about itself:

Earth has a new mini-moon, temporarily – See its orbit

The Catalina Sky Survey has discovered a small object, designated 2020 CD3, that may have been temporarily captured by Earth’s gravity.

This small moon is 2-3 meter in size.

Will bright star Betelgeuse go supernova?


This 18 February 2020 video says about itself:

Betelgeuse May Explode Anytime!

Betelgeuse is a red supergiant star located 650 light-years away from Earth. At the end of the year 2019, astronomers noticed that Betelgeuse is dimming.

Recent high-resolution images show that Betelgeuse is going through some changes. It is fading and changing its shape instead of round, it appears squashed into an oval.

Some astronomers also suspect that Betelgeuse has exploded already in the past but since it’s 650 light-years away from us, light will take 650 years to reach Earth.

Planet Mercury robbed by planet Venus?


This 16 January 2020 video says about itself:

Mercury’s outer layers may have been stripped off by a young Venus

Mercury may have been robbed by Venus in the early days of the solar system. A series of close passes between the two planets when they were young could have stripped away Mercury’s outer layers, leaving behind a world that is mostly dense core.

Read more here.