Archives de catégorie : sciences-general

Simulations explain giant exoplanets with eccentric, close-in orbits

by University of California – Santa Cruz, Oct 30, 2019 in ScienceDaily


As planetary systems evolve, gravitational interactions between planets can fling some of them into eccentric elliptical orbits around the host star, or even out of the system altogether. Smaller planets should be more susceptible to this gravitational scattering, yet many gas giant exoplanets have been observed with eccentric orbits very different from the roughly circular orbits of the planets in our own solar system.

Surprisingly, the planets with the highest masses tend to be those with the highest eccentricities, even though the inertia of a larger mass should make it harder to budge from its initial orbit. This counter-intuitive observation prompted astronomers at UC Santa Cruz to explore the evolution of planetary systems using computer simulations. Their results, reported in a paper published in Astrophysical Journal Letters, suggest a crucial role for a giant-impacts phase in the evolution of high-mass planetary systems, leading to collisional growth of multiple giant planets with close-in orbits.

Deducing the scale of tsunamis from the ’roundness’ of deposited gravel

by Tokyo Metropolitan University, August 25, 2019 in ScienceDaily


Scientists from Tokyo Metropolitan University and Ritsumeikan University have found a link between the “roundness” distribution of tsunami deposits and how far tsunamis reach inland. They sampled the “roundness” of gravel from different tsunamis in Koyadori, Japan, and found a common, abrupt change in composition approximately 40% of the “inundation distance” from the shoreline, regardless of tsunami magnitude. Estimates of ancient tsunami size from geological deposits may help inform effective disaster mitigation.

Journal Reference: Daisuke Ishimura, Keitaro Yamada. Palaeo-tsunami inundation distances deduced from roundness of gravel particles in tsunami deposits. Scientific Reports, 2019; 9 (1) DOI: 10.1038/s41598-019-46584-z

The Sun’s Weather Cycle May Start in ‘Tsunamis,’ End with ‘Terminators’

by Passant Rabbie, July 31, 2019 in Space


A tsunami of plasma rushes through the sun before a new sunspot cycle begins.

Astronomers may have finally figured out what causes the sun’s 11-year cycle of activity, and it involves a “tsunami” of magnetic fields.

The sun, like other stars, goes through a cycle marked by a change in magnetic activity, levels of radiation, and the number and size of sunspots. While our sun’s 11-year cycle was discovered more than a century ago, predicting exactly when one cycle ends and a new one begins has been an ongoing challenge.

A pair of related studies have mapped out the sun’s activity over the course of 140 years, looking for clues about the solar cycle that are visible on the surface. By looking at the way bright flashes of ultraviolet light migrate across the sun’s surface, the researchers discovered that the sun’s mysterious 11-year cycle may be marked by a “terminator” event that ends one cycle and a “tsunami” of magnetic fields that initiates a new one. Those bright flickers of ultraviolet light and the sun’s magnetic fields appear to drive the cycle itself, and monitoring those flashes could help scientists predict when a new cycle will begin.

LE PEER-REVIEW, IRREPROCHABLE ?

by Jo Moreau, 17 juillet 2019 in Belgotopia


Quel est le principe de fonctionnement du « peer review », ou révision par les pairs 

Nous avons déjà pu apprécier à quel point la publication d’un article dans une revue scientifique pratiquant le « peer review » constitue pour certains le sommet, et même la condition sine qua non pour se voir accorder l’autorisation d’émettre un avis sur un sujet donné (dans notre cas : le réchauffement, pardon, les changements climatiques).

L’exemple le plus récent est illustré par la position d’un réseau social bien connu qui émet un avis à la limite calomnieux à l’égard d’un physicien par ailleurs professeur d’université, qui a fait l’objet de mon article précédent : https://belgotopia.com/2019/07/15/menaces-ouvertes-sur-les-ecrits-giecosceptiques/

Comment cela fonctionne-t-il ? Le scientifique (ou le groupe de scientifiques) soumet son étude à l’éditeur de la revue qu‘il aura choisie (ou à plusieurs d‘entre eux). Il s’agit souvent du premier filtre, l’éditeur jugeant si l’étude est ou non conforme à la ligne éditoriale de la revue. Le physicien Edwin BERRY vient encore d’en faire l’expérience. Son étude « Le CO2 d’origine humaine a peu d’effet sur le CO2 présent dans l’atmosphère » a été refusée par l’American Journal of Climate Change sous le seul et unique motif que « La conclusion de cet article est complètement opposée au consensus de la communauté universitaire ». Evidemment, le fait que Ed BERRY soit un GIECosceptique affirmé n’aura pas favorisé sa démarche …

Super salty, subzero Arctic water provides peek at possible life on other planets

by University of Washington, July 12, 2019 in ScienceDaily


On Earth, scientists are studying the most extreme environments to learn how life might exist under completely different settings, like on other planets. A University of Washington team has been studying the microbes found in “cryopegs,” trapped layers of sediment with water so salty that it remains liquid at below-freezing temperatures, which may be similar to environments on Mars or other planetary bodies farther from the sun.

At the recent AbSciCon meeting in Bellevue, Washington, researchers presented DNA sequencing and related results to show that brine samples from an Alaskan cryopeg isolated for tens of thousands of years contain thriving bacterial communities. The lifeforms are similar to those found in floating sea ice and in saltwater that flows from glaciers, but display some unique patterns.

“We study really old seawater trapped inside of permafrost for up to 50,000 years, to see how those bacterial communities have evolved over time,” said lead author Zachary Cooper, a UW doctoral student in oceanography.

Low oxygen levels could temporarily blind marine invertebrates

by Scripps Institution of Oceanography at the University of California San Diego, May 8, 2019 in ScienceDaily


These results, published recently in the Journal of Experimental Biology, are the first demonstration that vision in marine invertebrates is highly sensitive to the amount of available oxygen in the water.

Oxygen levels in the ocean are changing globally from natural and human-induced processes. Many marine invertebrates depend on vision to find food, shelter, and avoid predators, particularly in their early life stages when many are planktonic. This is especially true for crustaceans and cephalopods, which are common prey items for other animals and whose larvae are highly migratory in the water column.

Research on terrestrial animals has shown that low oxygen levels can affect vision. In fact, humans can lose visual function in low oxygen conditions. Pilots flying at high altitude, for instance, have been shown to experience vision impairment if aircraft fail to supplement cockpits with additional oxygen. Additionally, health problems such as high blood pressure and strokes, both associated with oxygen loss, can damage vision.

What would happen to Earth’s Climate and Weather if we had no Moon?

by A. Watts, February 15, 2019 in WUWT


A provocative hypothetical question: What if the Moon was not there? Video follows.

This giant rock lights up the night and can even change colors. So what would we do without it? Would we all need night vision goggles? How would it affect the ocean tides? Our seasons? Or our sleep cycles? Or would the consequences be far more drastic?

As the closest celestial body to our planet, the moon exerts a gravitational pull that governs much of what happens here on Earth Take the sea, for example. If you like surfing, you can thank the moon when the moon’s gravitational pull tugs on our spinning Earth, the oceans respond, giving us high tides in some parts of the world, and low tides elsewhere.

New islands, happy feet: Study reveals island formation a key driver of penguin speciation

by Molecular Biology and Evolution (Oxford University Press), February 5, 201 in ScienceDaily


Ever since Darwin first set foot on the Galapagos, evolutionary biologists have long known that the geographic isolation of archipelogos has helped spur the formation of new species.

Now, an international research team led by Theresa Cole at the University of Otago, New Zealand, has found the same holds true for penguins. They have found the first compelling evidence that modern penguin diversity is driven by islands, despite spending the majority of their lives at sea.

“We propose that this diversification pulse was tied to the emergence of islands, which created new opportunities for isolation and speciation,” said Cole.

Over the last 5 million years, during the Miocene period, (particularly within the last 2 million years), island emergence in the Southern Hemisphere has driven several branches on the penguin evolutionary tree, and also drove the more recent influence of human-caused extinctions of two recently extinct penguin species from New Zealand’s Chatham Islands.

German Scientists To More Closely Investigate Cloud Formation, A Vital Component In Climate

by P. Gosselin, January 27, 2019 in NoTricksZone


Leipzig, 20 December 2018

Researchers from Leipzig cooperate with scientists from Punta Arenas (Chile) to learn more about the relationship between air pollution, clouds and precipitation.

Leipzig/Punta Arenas. How do airborne particles, so-called aerosols, affect the formation and life cycle of clouds and precipitation? In order to come one step closer to solving this question, atmospheric scientists from the Leibniz Institute for Tropospheric Research (TROPOS) and the Leipzig Institute for Meteorology (LIM) at Leipzig University will observe the atmosphere at one of the cleanest places in the world for at least a year. The choice fell on Punta Arenas because the city is located on a comparable geographical latitude as Germany and will thus enable comparisons between the northern and southern hemispheres. The measurement campaign is part of the International Year of Polar Prediction (YOPP), which aims to improve weather and climate forecasts for the polar regions through intensive measurements.

Meteoroid Hits the Moon During Recent Lunar Eclipse

by Anthony Watts, January 22, 2019 in WUWT


This is a treat. On Jan. 21st, a meteoroid slammed into the Moon. We know this because many amateur astronomers witnessed the explosion and recorded video and photos. The fireball was visible against the shadowy backdrop of a total lunar eclipse. Video of the event follows.

We know this because many amateur astronomers witnessed or photographed the explosion. Petr Horálek was one of them; he captured the fireball from Boa Vista, one of the islands of Cape Verde …

Scientists identify two new species of fungi in retreating Arctic glacier

by Research Organization of Information and Systems, January 15, 2019 in ScienceDaily


Two new species of fungi have made an appearance in a rapidly melting glacier on Ellesmere Island in the Canadian Arctic, just west of Greenland. A collaborative team of researchers from Japan’s National Institute of Polar Research, The Graduate University for Advanced Studies in Tokyo, Japan, and Laval University in Québec, Canada made the discovery.

The scientists published their results on DATE in two separate papers, one for each new species, in the International Journal of Systematic and Evolutionary Microbiology.

“The knowledge of fungi inhabiting the Arctic is still fragmentary. We set out to survey the fungal diversity in the Canadian High Arctic,” said Masaharu Tsuji, a project researcher at the National Institute of Polar Research in Japan and first author on both papers. “We found two new fungal species in the same investigation on Ellesmere Island.”

Bacterial origin of the red pigmentation of Phanerozoic carbonate rocks: an integrated study of geology-biology-chemistry

by A. Préat et  al., December 2018 in GeologicaBelgica (with .pdf)


Abstract

Explaining the color of rocks is still a complex problem. This question was raised long ago in the community of geologists, particularly for the pigmentation of the ‘red marbles’ of the Frasnian of Belgium at the beginning of the last century, with many unsatisfactory hypotheses. Our recent analysis of different red carbonate rocks in Europe and North Africa (Morocco) may provide an alternative explanation for the color of these rocks. For this it was necessary to bring together diverse and complementary skills involving geologists, microbiologists and chemists. We present here a synthesis of these works. It is suggested that the red pigmentation of our studied Phanerozoic carbonate rocks, encompassing a time range from Pragian to Oxfordian, may be related to the activity of iron bacteria living in microaerophilic environments. A major conclusion is that this red color is only related to particular microenvironments and has no paleogeographic or climatic significance. All red carbonates have not necessarily acquired their pigmentation through the process established in this review. Each geological series must be analyzed in the light of a possible contribution of iron bacteria and Fungi.

Mars: Oxygen-rich, life-supporting liquid water?

by California Institute of Technology, October 22, 2018 in ScienceDaily


A team led by scientists at Caltech and the Jet Propulsion Laboratory (JPL), which Caltech manages for NASA, has calculated that if liquid water exists on Mars, it could — under specific conditions — contain more oxygen than previously thought possible. According to the model, the levels could even theoretically exceed the threshold needed to support simple aerobic life.

That finding runs contrary to the current, accepted view of Mars and its potential for hosting habitable environments. The existence of liquid water on Mars is not a given. Even if it is there, researchers have long dismissed the idea that it might be oxygenated, given that Mars’s atmosphere is about 160 times thinner than that of Earth and is mostly carbon dioxide.

Ancient Mars had right conditions for underground life, new research suggests

by Brown University, September 24, 2018 in ScienceDaily/EPSL


A new study shows evidence that ancient Mars probably had an ample supply of chemical energy for microbes to thrive underground.

“We showed, based on basic physics and chemistry calculations, that the ancient Martian subsurface likely had enough dissolved hydrogen to power a global subsurface biosphere,” said Jesse Tarnas, a graduate student at Brown University and lead author of a study published in Earth and Planetary Science Letters. “Conditions in this habitable zone would have been similar to places on Earth where underground life exists.”

New research shows that ancient Mars likely had ample chemical energy to support the kinds of underground microbial colonies that exist on Earth.
Credit: NASA / JPL

BBC tells journalists that IPCC is God, can not be wrong –”No debate allowed”

by JoNova, September 8, 2018


Lets all bow to the IPCC — a modern God that shalt not be questioned. The Holy Sacred Climate Cow!

The IPCC is an unaudited and unaccountable foreign committee. Not only are no scientists paid to check its findings, now the publicly mandated BBC is making sure none of their journalists will check its findings either.

Carbonbrief has a copy of the BBC new internal guidance on how to report climate change.

In April, the UK regulator, Ofcom, found the BBC was guilty of not sufficiently challenging Lord Lawson, a skeptic. So in response the BBC now promises they will never sufficiently challenge the IPCC. That’s “false balance” for you.

Direct evidence of surface exposed water ice in the lunar polar regions

by Shaui Li et al., August 20, 2018 PNAS


We found direct and definitive evidence for surface-exposed water ice in the lunar polar regions. The abundance and distribution of ice on the Moon are distinct from those on other airless bodies in the inner solar system such as Mercury and Ceres, which may be associated with the unique formation and evolution process of our Moon. These ice deposits might be utilized as an in situ resource in future exploration of the Moon.

Integrated genomic and fossil evidence illuminates life’s early evolution and eukaryote origin

by Holly C. Betts et al., August 20, 2018 in NatureEcology&Evolution


We derive a timescale of life, combining a reappraisal of the fossil material with new molecular clock analyses. We find the last universal common ancestor of cellular life to have predated the end of late heavy bombardment (>3.9 billion years ago (Ga)). The crown clades of the two primary divisions of life, Eubacteria and Archaebacteria, emerged much later (<3.4 Ga), relegating the oldest fossil evidence for life to their stem lineages. The Great Oxidation Event significantly predates the origin of modern Cyanobacteria, indicating that oxygenic photosynthesis evolved within the cyanobacterial stem lineage. Modern eukaryotes do not constitute a primary lineage of life and emerged late in Earth’s history (<1.84 Ga), falsifying the hypothesis that the Great Oxidation Event facilitated their radiation…

The Medusae Fossae Formation as the single largest source of dust on Mars

by L. Ojha et al., July 20, 2018 in NatureCommunications (open access)


Transport of fine-grained dust is one of the most widespread sedimentary processes occurring on Mars today. In the present climate, eolian abrasion and deflation of rocks are likely the most pervasive and active dust-forming mechanism. Martian dust is globally enriched in S and Cl and has a distinct mean S:Cl ratio. Here we identify a potential source region for Martian dust based on analysis of elemental abundance data …

Invisible Scientific Debates Accomplish Nothing

by Donna Laframboise, April 23, 2018 in ClimateChangeDispatch


SPOTLIGHT: After the Intergovernmental Panel on Climate Change (IPCC) report was released in 2007, its dramatic findings of species extinction were repeatedly emphasized by chairman Rajendra Pachauri.

BIG PICTURE: When it examined the question of species extinction, the 2007 IPCC report relied heavily on a single piece of research – a Nature cover storypublished early in 2004. Written by Chris Thomas and 18 others, this was the source of Pachauri’s claim that climate change threatened 20 to 30% of the world’s species.

Clear as mud: Desiccation cracks help reveal the shape of water on Mars

by Geological Society of America and in Geology, April 19,2018 in ScienceDaily


.pdf of the article

In early 2017 scientists announced the discovery of possible desiccation cracks in Gale Crater, which was filled by lakes 3.5 billion years ago. Now, a new study has confirmed that these features are indeed desiccation cracks, and reveals fresh details about Mars’ ancient climate.

“We are now confident that these are mudcracks,” explains lead author Nathaniel Stein, a geologist at the California Institute of Technology in Pasadena. Since desiccation mudcracks form only where wet sediment is exposed to air, their position closer to the center of the ancient lake bed rather than the edge also suggests that lake levels rose and fell dramatically over time.

Scientists discover first super salty subglacial lakes in Canadian Arctic

by University of Alberta, April 11, 2018 in ScienceDaily


Super salty water beneath ice could serve as a terrestrial analogue for a habitat for life on other planets.

An analysis of radar data led scientists to an unexpected discovery of two lakes located beneath 550 to 750 meters of ice underneath the Devon Ice Cap, one of the largest ice caps in the Canadian Arctic. They are thought to be the first isolated hypersaline subglacial lakes in the world.

Science is Not Truth

by Donna Laframboise, April 4, 2018 in ClimateChangeDispatch


SPOTLIGHT: As the influence of religion has waned, we’ve placed science on a pedestal – mistaking it for an oracle of truth.

BIG PICTURE: Richard Harris has written a startling book about the state of medical research. The preface to Rigor Mortis: How Sloppy Science Creates Worthless Cures, Crushes Hope, and Wastes Billions includes a warning about scientific naivety:

Most of science is built on inference rather than direct observation…Science progresses by testing ideas indirectly, throwing out the ones that seem wrong…Gradually, scientists build stories that do a better job of approximating the truth.

Earth’s stable temperature past suggests other planets could also sustain life

by Anthony Watts,  April 3, 2018 in WUWT


Theories about the early days of our planet’s history vary wildly. Some studies have painted the picture of a snowball Earth, when much of its surface was frozen. Other theories have included periods that would be inhospitably hot for most current lifeforms to survive.

New research from the University of Washington suggests a milder youth for our planet. An analysis of temperature through early Earth’s history, published the week of April 2 in the Proceedings of the National Academy of Sciences, supports more moderate average temperatures throughout the billions of years when life slowly emerged on Earth. (…)

Mars’ oceans formed early, possibly aided by massive volcanic eruptions

by University of California-Berkeley, March 19, 2018 in ScienceDaily


A new theory about how oceans and volcanoes interacted during the early history of Mars supports the idea that liquid water was once abundant and may still exist underground. Geophysicists propose that the oceans originated several hundred million years earlier than thought, as the volcanic province Tharsis formed, and that greenhouse gases enabled the oceans. The theory predicts smaller oceans, more in line with estimates of water underground and at the poles today.