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.