Unusual: Northern Lights on a comet!

Tuesday, September 22, 2020 at 8:22 PM – The Aurora Borealis is spectacular, but it doesn’t just happen on Earth. Astronomers have observed the phenomenon on a comet. Explanations.

The Aurora Borealis is a spectacular phenomenon observed mainly in northern latitudes. These are solar winds charged with electrons that strike the Earth’s upper atmosphere. It is not only on Earth that this spectacle occurs. In fact, astronomers took advantage of the instruments of the European Space Agency’s Rosetta probe to collect data that would bring to light an extraordinary spectacle: the northern lights on a comet!

The Northern Lights have been observed elsewhere in the solar system. Most planets and moons that have an atmosphere can give rise to this spectacle, including Jupiter, Saturn, Uranus, Neptune, and Mars. However, this is the first event reported on a comet.

Data collected by scientists indicate that this is indeed an auroral phenomenon. The electron-charged particles interact with the gas emitted by the comet. The resulting atoms give off ultraviolet light. However, this radiation is invisible to the naked eye.

SEE ALSO: Record ice deficit in the Arctic


The big player who could upset the Quebec fall, here he is

Monday, September 14, 2020 at 6:00 AM – La Niña, the temperature anomaly in the mid-west Pacific Ocean, is low in intensity but is expected to gain strength within a few weeks. If this scenario materializes, the repercussions will be felt as far as the Atlantic, and the Quebec fall could indirectly suffer the consequences.

Hyper-tropical season

Hurricane season is in full swing, to say the least, knowing that we recorded more than fifteen named storms during the first half of the season, whereas in normal times we has twelve for a full season that ends November 30 in the Northern Hemisphere.

The 2020 season could dethrone the year 2005 when it comes to the number of named tropical storms. This tropical hyperactivity could upset the tendency for mildness expected in our Fall preview.

Hurricanes - favorable factors

One of the causes of this tropical hyperactivity is the negative anomaly of water temperatures in the Pacific, commonly known as La Niña. One of the characteristics of La Niña is a weak windshear in the Atlantic. Associated with the warmer temperatures in this ocean, this lack of shear offers tropical waves the perfect conditions to emerge, first, and gain in intensity, second.


According to the US Agency for Ocean and Atmospheric Observation (NOAA), La Niña is well established, which means tropical hyperactivity in the Atlantic will continue until late fall. This could upset weather trends in Quebec.

The aftermath in Quebec

When a hurricane moves, warm surface water is mixed with deep water. The more tropical storms there are, the cooler the surface water is. Yet it is thanks to these warm Atlantic waters that an atmospheric ridge should allow the province to enjoy milder weather this fall.

Hurricanes - Cold water influence

“With cooler surface water, the ridge may be less well defined and the heat from the United States may not rise enough towards the province for the northernmost sectors to benefit,” explains Anne-Sophie Colombani , videographer-meteorologist at MétéoMédia.

Ouagan - cretage reduction

In addition, if tropical storms approach the coast, it is possible that they are caught by the jet stream and directed towards Quebec or the Maritimes. “Significant amounts of precipitation could be spilled over parts of the province,” said Colombani, adding that “the number of days with precipitation would not be higher than seasonal norms, but the amounts of rain could be” .

Hurricanes - precipitation

To find our Fall Snapshot, go here.

To know more…

The girl

In the west-central Pacific Ocean, climatologists and meteorologists around the world are monitoring the Southern Oscillation, or water temperature anomalies. If this anomaly is greater than +0.5 ° C, we speak of El Niño; when it is less than -0.5 ° C, it is La Niña; and between these two values, the anomaly is considered to be neutral.

To be qualified as El Niño or La Niña, an anomaly must remain stable for three months in a row. NOAA has just announced that after August having recorded an anomaly of less than -0.5 ° C, “La Niña conditions are now present”.



Vilfand promised warming up to 24 degrees in the European part of Russia :: Society :: RBC

Photo: Komsomolskaya Pravda / Global Look Press

Warming is expected in the European part of Russia on September 17, this Thursday will be the warmest day of the current week. This was stated by the scientific director of the Hydrometeorological Center of Russia Roman Vilfand, reports RIA Novosti.

According to him, on September 17 the air will warm up to plus 21-23 degrees, and in some places up to plus 24 degrees.

The specialist said that after a short-term warming, the temperature will drop again. As Vilfand explained, the atmospheric front will move to the center of the European part of Russia, which will cause a cooling by 6-8 degrees.

“Next weekend will not be as comfortable as this one. As soon as such cold weather is noted, one should rejoice and wait for Indian summer, ”the head of the Hydrometeorological Center said.

Wilfand assessed the likelihood of recognizing 2020 as the warmest year in history

Photo: Mario Tama / Getty Images


The Moon is rusting (and we have to dust it off)

An electron gun to make moon dust

You have to think of everything before going back to the moon andconsider installing an inhabited base there. How to build buildings and insulate them from extreme temperatures? How to protect yourself from radiation and micrometeorites? How to produce water and oxygen? And most importantly… How to get rid of this awful and unbearable gray dust that sticks everywhere? The astronauts of the Apollo missions often complained about it: the lunar regolith, the rock dust that covers the surface of the star, is very fine, both sticky and abrasive. She clings to the suit without being able to dislodge it, stiffens her joints and damages her boots. It covers the solar panels and the visors of the helmets.

Astronaut Charles Conrad Jr picking up a rock sample, boots stained with dust, during the Apollo 12 mission in November 1969. Photo Nasa

In 2017, an American doctoral student worked for NASA on the design ofa combination that would repel regolith. Today, researchers at the University of Colorado at Boulder have a complementary new idea: what if we cleaned the dust with an electron beam? In a vacuum chamber, they carried out the test with a kind of electron gun on dusty surfaces… and the regolith flies away as if by magic. The negative charge of the electrons builds up on the target area, until the surface and dust “Repel each other” like magnets, explains Xu Wang, co-author of the study published in Astronautics Act.

Read also Colonization of the Moon: the special conquest

When the earth makes the moon rust

Not only is the Moon dusty, it rusts too! University of Hawaii planetologist Shuai Li recently delved into data recorded by the Indian probe Chandrayaan-1, which orbited the Moon for nine months in 2008-2009. And he noticed an interesting thing: in the polar regions, the light reflected from the surface of the Moon seemed to carry the spectral signature of thehematite, an iron oxide. We know that the Moon is full of iron rocks, but by what miracle were they able to oxidize, when there is neither liquid water nor oxygen on our satellite?

Mineralogical map of the Moon produced with the Indian probe Chandrayaan-1.  Areas in blue show water, concentrated (as ice) at the poles.  This is where the hematite was detected.Mineralogical map of the Moon produced with the Indian probe Chandrayaan-1. Areas in blue show water, concentrated (as ice) at the poles. This is where the hematite was detected. Image ISRO/NASA/JPL-Caltech/Brown University/USGS

Shuai Li requested NASA’s assistance to verify his find. “At first, I didn’t believe it, testifies Abigail Fraeman, geophysicist at NASA. It shouldn’t exist, because of the conditions on the moon. ” But after analysis, it confirms the presence of hematite on the Moon. It remained to explain its origin. A hint: there is more hematite on the visible side of the Moon than on its far side. The team led by Shuai Li therefore hypothesizes, this week in Science Advances, that oxygen traveled from Earth’s atmosphere to the Moon, along the tail of Earth’s magnetosphere. But is it recent, or very old? It will be necessary to measure the isotopes of oxygen in the lunar hematite to estimate its age. Oxygen could very well have approached the Moon when it was much closer to the Earth, a few billion years ago.

Tripled stars make leaning planets

Our solar system is simple, flat and well organized: all the planets orbit globally on the same plane. But how does this work in more complex systems, with three stars for example? Well, it’s a mess and the planets are going all over the place!

A team of astronomers described in the magazine Science of the week, the GW Orionis planetary system, which they managed to photograph with the Very Large Telescope in Chile. Located 1300 light years away, GW Orionis is still young. It has three suns and an immense cloud of dust which will gradually aggregate to give birth, in a few million years, to planets. This nursery is called the protoplanetary disc. However, astronomers discovered in the detailed photo of GW Orionis that its disk is twisted, and that it contains a dust ring with a completely different orientation. The proof: this ring casts a shadow on the rest of the disk around it.

On the right, the photo of GW Orionis showing the central ring separated from the protoplanetary disc, on which it casts a shadow.  Left, artist's impression of the disc and the dust ring in 3D, from the photo.On the right, the photo of GW Orionis where we see the central ring separated from the protoplanetary disc, on which it projects a shadow. Left, artist’s impression of the disc and the dust ring in 3D, from the photo. ESO / L images. Calçada, Exeter / Kraus et al.

“Any planet formed within the inclined ring will be characterized by a strongly inclined orbit around the star”, predicts researcher Alexander Kreplin from the University of Exeter in the United Kingdom, co-author of the study.

The vast majority of stars have a companion, even two or more. We will therefore not fail to observe other systems with planets orbiting on a very different plane. It only lacks a little technology to successfully observe them, because unlike the protoplanetary disk of GW Orionis, which reflects the light of its stars well, the planets already formed are dark and difficult to spot (we often guess the presence of exoplanets indirectly, by detecting movement or variations in the luminosity of their star). But Alexander Kreplin is confident: “We believe that we will be able to discover in the future many planets in oblique, very distant orbits, as part of planetary imaging campaigns, carried out using in particular the ELT.” L’Extremeley Large Telescope, European, is under construction in Chile and should come into operation around 2025.

Portrait in the sun of Comet Neowise

Comet Neowise passed closest to the Sun on July 3, 2020, at a distance of only 43 million kilometers… and it survived. “Other comets often break into several pieces, due to the thermal and gravitational stress undergone when approaching the Sun, recalls NASA. But this photo taken by Hubble shows that the solid core of Neowise apparently remained intact. ”

After being the star of the summer, parading in the night sky with enough light to be admired with the naked eye, with binoculars, and to be photographed by all the amateurs, the comet Neowise continues to be scrutinized by the professional instruments. The space telescope Hubble shot him the picture on August 8, zooming to the maximum. We cannot distinguish the matter (rock and ice) from the core, but we can distinguish the two jets of dust and gas ejected by the comet, which go in opposite directions. This gas cloud is 18,000 kilometers wide in the photo.

Photo of comet Neowise (C / 2020 F3) taken from the ground on July 16, 2020. In the insert, a Hubble photo taken on August 8, 2020 after the perihelion passage.Photo of comet Neowise (C / 2020 F3) taken from the ground on July 16, 2020. In the inset, Hubble photo taken on August 8, 2020 after the perihelion passage. Images Zoltan G. Levay & NASA, ESA, STScI, Q. Zhang (Caltech)

Camille Gevaudan


Covid and children, symptoms: how to distinguish them

Cough, runny nose, a little fever. It is inevitable, every year children frequently encounter a colds if not the flu. These little ailments are normal, nothing to worry about. But this year will be different and parents all over the world will ask themselves: “Does my child have Covid, the flu or is it a simple cold?”.

Coronavirus and children, how sick they get and how contagious they are: what we know
Children are not immune
How do you know if it’s flu, cold or Covid?

It is probably not possible to reliably distinguish Covid from influenza because the symptoms are really very similar and the only certain way to make a differential diagnosis is andfollow the swab. The most common symptoms of Covid-19 in children are cough or fever or both with colds and gastrointestinal symptoms (present in 30% of children). There are many other potential ways the virus presents itself in positive children: loss of taste and smell, abdominal pain, headache, sore throat, breathing difficulties. Unfortunately, some of these symptoms are the same that characterize other diseases that circulate during the winter season. A Centers for Disease Control an Prevention (CDC) chart indicates how often these symptoms overlap. To limit the risk of misdiagnosis as much as possible, pediatricians suggest vaccinating their children against the flu: in the event of symptoms, if a child has had the vaccine, it is more likely that it will be Covid-19


How to orient yourself: the single symptom must not alarm

However, we can try to make some distinctions to help parents orient themselves with a series of common sense advice. “If the child has a cold accompanied by a stuffy or runny nose and a few coughs swithout other symptoms as gastrointestinal disorders and true conjunctivitis (not the one with catarrhal discharge, which is part of the cold) we can conclude with enough certainty that we are facing a classic seasonal cooling ” explains Gianvincenzo Zuccotti, director of the Pediatrics department at the Buzzi hospital in Milan. The situation is different in which the child manifests more than one symptom. “If a fever above 37.5 and maybe even gastrointestinal symptoms such as vomiting and diarrhea are added to the cold, then it is right to suspect Covid-19” adds Professor Zuccotti. “In general, if the symptoms occur individually: only cold, only fever, only vomiting and diarrhea, it is likely that we are facing seasonal ailments, the classic colds and viral gastroenteritis that accompany winter and not Covid-19 “

Loss of taste and smell

The most characteristic symptom of Covid is the loss of taste and smell. From the source of this signal we can be quite sure that it is coronavirus. Usually the loss of smell is sudden and severe and is not accompanied by a stuffy nose or runny nose: most people affected by coronavirus can still breathe freely. Loss of taste is also another characteristic sign of Covid and also in this case between the “normal” loss of taste due to nasal congestion and the coronavirus symptom there are differences: coronavirus patients with loss of taste are not really able to distinguish between bitter or sweet. “However, these are subjective symptoms – warns Zuccotti – and it is difficult to have children under six tell them about them”.

Dry cough

Unlike the influences the cough, in case of Sars-CoV-2 it is dry, cross and insistent, more typical of asthma but not so infrequent during the winter season. “During the winter, in addition to the flu, the respiratory syncytial virus (RSV) also circulates, capable of infecting the respiratory system, causing asthma-like bronchitis and bronchiolitis with an irritating cough as a symptom and a differential diagnosis will therefore be necessary. Many times, however, these forms do not cause fever “adds the pediatrician.

Getting to know your children

Parents are the ones who know their children best and are the first to know if something is wrong. For example, if the child has a runny nose and is allergic to ragweed, it is likely that that symptom is linked to seasonal allergy. Furthermore, allergic forms are rarely accompanied by fever. Same thing for asthma sufferers and shortness of breath. However, if the symptoms are out of the ordinary then it is good to talk to your pediatrician.

When should the child be kept home from school?

Children, especially those under the age of six, often spend the entire winter permanently cold. Will they always have to stay home from school? “When it comes to an isolated cold with a few strokes cough, perhaps more frequent during changes of position (when going to bed or getting up than the rest of the day) frequency is not contraindicated. I would limit myself to keeping only the child at home from school with a fever of over 37.5, cough and possibly diarrheal symptoms, as happens normally »concludes Zuccotti.

The importance of sentinel centers in understanding the virus

The director of the Buzzi pediatrician department proposes the creation of sentinel centers to monitor the virus. «It’s one thing to do random swabs on children with colds and always find negative swabs. At that point all the viral forms that are circulating will not worry us. But when the surveillance system begins to isolate the coronavirus in children with a single cold or with only intestinal ailment, then an alert must be sent because all the diagnostic parameters would have to be reconsidered “

2 September 2020 (change 2 September 2020 | 12:03)



Coronavirus, in what order do the symptoms develop?

A chill followed by a stomach ache. Or an annoying sore throat, perhaps after an evening spent on the beach with a little breeze. Will it have Covid? And away with the memory to think about when there could have been contacts at risk. At the restaurant? At the beach bar? The queue at the supermarket checkout? In the meantime, as a precaution, one silently isolates oneself a little from other family members, perhaps sleeping alone, warning one’s closest friends of a malaise that in other times would never have been reported. A summer sore throat just a year ago would have been cataloged as a normal episode, today it can cause concern.

The importance of recognizing the symptoms

Recognizing the first symptoms of Covid-19 is fundamental to intercept a possible infection, but without being seized by anxiety. We know that the symptoms of a Sars-CoV-2 infection are very similar to those of the flu, so much so that at the beginning of the epidemic, not distinguishing the two diseases caused the widespread spread of Covid-19 throughout the world. evident that the differential diagnosis is possible only with the swab but now a study published in the journal Frontiers in Public Health by a group of researchers from the University of Southern California at Los Angeles has identified the most common temporal order of the symptoms of Covid-19, also identifying how this ranking changes compared to other respiratory diseases, in particular those caused by the influenza virus and the coronaviruses that cause Sars and Mers.

The Covid order

The study results indicate that Covid-19 tends to start with fever, then progress to cough and muscle aches, followed by nausea and vomiting, and eventually diarrhea. The flu, on the other hand, most often begins with a cough, followed by a fever. Sars and Mers are similar to Covid-19: fever and cough, but in third place there is diarrhea, before nausea and vomiting.

The secondary symptoms

To draw up the ranking, the researchers used the data released by the WHO relating to over 55,000 cases of Covid-19 confirmed in China, comparing them with thousands of cases of seasonal flu collected by the University of Michigan, of almost 150 cases of Sars registered in the ‘Toronto area and 45 cases of MERS reported in South Korea. Researchers have shown that even in the presence of secondary clinical manifestations, such as sore throat, headache or exhaustion, the sequence of the main symptoms remains in most cases unchanged. This means that there is a high probability that the fever will appear first, confirming among other things the importance of measuring the body temperature to contain the spread of the coronavirus.

Not a diagnostic method

The order of symptoms is important, the author said Joseph Larsen, expert in computational biology and bioinformatics. Knowing that each disease progresses differently means that doctors can identify earlier whether it is Covid-19 or another disease by making better treatment choices. Larsen and colleagues explained that their model is not intended as a do-it-yourself diagnostic method, but it can help to decide, for example, to isolate oneself in advance while awaiting a screening that clarifies the actual positivity.

August 31, 2020 (change September 1, 2020 | 09:14)



750 million genetically modified mosquitoes released in the United States

Sunday, August 30, 2020 at 6:07 PM – A veritable hordes of genetically modified mosquitoes will be released in the United States, with the aim of reducing the transmission of certain diseases dangerous to humans.

The states of Texas and Florida are targeted. The insects will therefore be introduced gradually over a period of about two years.

Male mosquitoes that are released will release a lethal gene in females already in circulation. When mating, this same discomfort will make them sterile.

The goal is to wipe out a whole species of insects carrying viruses potentially fatal to humans, such as Zika or dengue.

This impressive operation would have no significant impact on humans or the environment, according to current analyzes. That was the initial objective: to find an ecological way to eliminate the species of mosquitoes carrying diseases.

SEE ALSO: Despite a global decline in insects, mosquitoes are doing well


Covid-19: what do we know today about the transmission of the virus by aerosols in confined spaces?

Question asked by BARALE on 08/22/2020


The start of the school year is masked, In the enterprises as in classrooms. Before these decisions were made, one could read, in Libé on August 14, a forum of a collective of “health professionals” (“Covid-19: the risk exists in all enclosed places, in classrooms as well as in offices”) : “We affirm it without ambiguity: Sars-CoV-2 is transmitted through the air and does not make the mask compulsory in classrooms or amphitheatres, in open spaces, meeting rooms, workshops and shared offices does not comply with science and WHO data. ”

In the light of these very affirmative lines, you ask us about the state of science about the transmission of the virus in the air. There is in fact no consensus on the circulation of Covid-19, from one individual to another in the general population, via “aerosols”, these microdroplets which remain in suspension and which could be vectors of active virus. and infectious.

Two doctors, authors of the forum, recognize from CheckNews that the wording “without ambiguity: Sars-CoV-2 is transmitted through the air ” is not ideal. But that it responds to a precautionary principle: there is a risk that airborne transmission exists, including outside hospitals or laboratories (where it has been documented).

You also asked us Is wearing a mask outside useful?

Warning from scientists

At the beginning of july, 239 scientists from 30 countries warn about the aerosol distribution of the virus. Addressing international health institutions (including the WHO) and national, they recommend great vigilance regarding the transmission of the virus by microdroplets: “Of course, aerosol transmission of Sars-CoV-2 is not yet universally recognized; but, according to our collective assessment, there is sufficient evidence that the precautionary principle should apply. In order to control the pandemic, while waiting for the possibility of vaccination, all transmission routes must be cut off. ”

Several articles or forums have been devoted to the impact of this publication on the authorities (in French, in English). In France, the Director General of Health, Jérôme Salomon, approached the High Council for Public Health. The HCSP had already expressed itself on the subject in a notice published on April 8 (and to a lesser extent in a notice published on April 24).

In this April text, we read in particular: “Aerosol transmission is biologically plausible when (1) infectious aerosols are generated by or from an infectious person, (2) the pathogen remains viable in the environment for a period of time, and (3) tissues targets in which the pathogen initiates infection are accessible by aerosol. […] For Sars-CoV, the level of evidence for aerosol transmission indicates that the evidence for conditions 1 and 3 is moderate and strong for condition 2. “

CheckNews also made a point on the state of science regarding aerosolization at the beginning of April. In an article published in May on the circulation (or not) of the new coronavirus in air conditioning, we also wrote: “Although it is possible for smaller virus particles to remain suspended in the air (this is called an aerosol), an infection requires that a sufficiently large number of active copies of the virus enter the body: this is the infectious dose. In the vast majority of situations, wind, drafts and ventilation reduce the concentration of viruses in the air, which significantly lowers the risk of infection. On the other hand, a greater risk seems to exist in intensive care situations, in premises where caregivers remove their protection and in hospital toilets. “

Opinion of the High Council for Public Health

After a request from the DGS, the HCSP therefore produced a new opinion, dated July 23: “Sars-CoV-2: updating of knowledge on the transmission of the virus by aerosols.” Conclusion ? “The HCSP considers that after updating the data in the literature, airborne transmission of the Sars-CoV-2 virus should be considered in enclosed spaces, in particular poorly ventilated and insufficiently ventilated, and in outdoor gatherings.” And to urge the public to wear a mask “In all enclosed public and private collective places as well as in the event of a gathering with a high density of people outdoors in order to limit the emission of respiratory particles.”

More specifically, the High Council cites several scientific studies published in recent weeks on the subject. One, published in early April in Nature concludes that “Aerosol transmission is a potential mode of transmission of coronaviruses, such as influenza and rhinoviruses.” The results ofanother, published in June 2020 from laboratory experiments, suggest that the“Infectivity and virionic integrity [du Sars-CoV-2] can be kept for up to 16 hours in aerosols of a breathable size ”.

The HCSP also refers to a literature review produced by the Canadian National Collaborating Center for Environmental Health (funded by the Public Health Agency of Canada) regarding “Risks and precautions associated with Covid-19” as part of choral singing. The CCNSEA notes in particular that “More and more, it is believed that transmission by small droplets or by aerosols produced during speaking, singing, shouting or breathing is a major route of contagion. […] Aerosol transmission could occur in contexts where particles accumulate in closed, unventilated rooms where many people are gathered for a long period ”. In the opinion of the HCSP, some case studies follow which have “Describes the occurrence of contamination by the Sars-CoV-2 virus of people gathered in confined spaces”.

In the laboratory, in the hospital, in general

In this opinion, the HCSP therefore identifies studies that point in the same direction: airborne transmission of Sars-CoV-2 is possible. But it is not possible in the same proportions, depending on the situation.

Thus, the High Council writes “take into account” two elements. First, the open letter from scientists mentioned at the beginning of the article. Didier Lepelletier, co-chair of the HCSP Covid-19 permanent working group, points out that this letter was written by physicists, “Who believe that the dichotomy between droplet and microdroplet [aérosol] is irrelevant, for them everything is aerosol ”. What’s more, continues the head of the Bacteriology – Hospital Hygiene Department of the Nantes University Hospital: these physicists “Are based on models, for example in the laboratory, which for some have suggested that the virus could circulate in the form of aerosols”.

Second element considered by the HCSP for its opinion this summer: a position statement from the beginning of July from the WHO. It is fully readable (and in English), or in summary form (in English), tells us the World Health Organization.

“Is the virus spread by aerosols?” wonders the WHO, which distinguishes two cases. On the one hand, in a healthcare setting: “Some medical procedures can produce very small droplets that can stay airborne for longer periods. [par exemple une intubation ou une extubation]. When such medical procedures are performed on people infected with Covid-19 in healthcare facilities, these aerosols may contain the Covid-19 virus. These aerosols can potentially be inhaled by other people if they are not wearing the appropriate personal protective equipment. ”

Another scenario, in the general population (excluding hospitals): “Cases of Covid-19 have been reported in some closed places, such as restaurants, nightclubs, places of worship or workplaces where people can shout, talk or sing. In these cases, aerosol transmission, especially in those closed places where there are overcrowded and insufficiently ventilated spaces where infected people spend long periods with other people, cannot be excluded. ” And the WHO to insist (like the HCSP): “Further studies are urgently needed to study these cases and assess their importance for the transmission of Covid-19.”

Less contagious than chickenpox

“There is never only one mode of transmission of a virus, recalls Didier Lepelletier, but there is always a preferential mode. “ It can be hand-carried, or aerial for example. And among the modes of aerial transmission, there are therefore, schematically, droplets and aerosols. In the current state of knowledge (and for several weeks), “Droplets are a preferential mode of transmission over aerosols”, observes the member of the HCSP.

Several scientists contacted believe that if aerosols were the main vector of Sars-CoV-2, the R0 (initial reproduction number) would be much higher. As it is, for example, for pulmonary tuberculosis or chickenpox (which are transmitted by aerosol). Whose R0 fluctuates around 10 (much more than for Covid-19).

In a recent study published in the British Medical Journal, the authors find that the risk that a person without symptoms (but who can, for example, emit aerosols just by breathing or talking) contaminates those around them depends on the density of people, their activity and ventilation. This is in line with what the High Council expressed in its opinion of 23 July, according to which “Three favorable conditions are to be remembered concerning the transmission of the virus: the conditions of ventilation and air flow; atmospheric conditions (low temperature, humidity); physical activities and efforts practiced in confined spaces ”.

It should be noted that neither the HCSP, nor the WHO (nor the signatories of the forum cited above) explicitly recommend wearing a mask outside of these situations (for example in general, in the street). Still, specialists in these subjects would like to see studies develop to better understand the modes of transmission of this virus.

In summary : aerosols do not appear to be the preferred mode of transmission on Sars-CoV-2. However, certain observations in hospitals or in laboratories suggest that there may be airborne transmission, without there being a consensus on the risk or the probability of it occurring. In the general population, there is no proof or scientific measurement of the risk of airborne transmission, but this risk is probable according to the scientific community, and it is all the more important in poorly ventilated environments or outdoors in the event of large gatherings. Hence an incentive, under these conditions, to wear the mask in a closed environment, under the precautionary principle.

Fabien Leboucq


Vilfand promised a temperature above normal on the last day of summer in Moscow :: Society :: RBC

Photo: Konstantin Kokoshkin / Global look Press

In Moscow, on the last day of summer, there will be an abnormal heat, and then on Tuesday, September 1, there will be a sharp cold snap. About it TASS said the scientific director of the Hydrometeorological Center of Russia, Roman Vilfand.

“The temperature will start to rise on Sunday, and on Monday it will already be 25-30 degrees. The temperature is very high, exceeding the norm by about six degrees, ”the meteorologist said.

Then, according to Vilfand, a noticeable cooling will begin, the temperature may drop to 20-25 degrees Celsius. “No significant precipitation is forecasted on this day. The temperature background and weather conditions will be approximately the same on Wednesday, ”he added.

Forecasters promised a cold snap in Moscow next week

Wilfand previously reported about an abnormally warm end of summer almost throughout Russia. According to him, practically throughout the entire territory of the country, the temperature background is predicted to be 2-8 degrees higher than normal.


5 great mysteries above our heads.

Wednesday, August 26, 2020 at 10:01 AM – As a child, I loved lying on the floor just to look at the stars. I felt like I was losing myself in the infinitely large. It’s something that I still enjoy doing today. And you ? Have you taken the time to observe the sky? There are some things you absolutely must see. Here they are.

Rain of Perseids - Credit michal-mancewicz-Q6ypnqRk2U0-unsplash


The Perseids are a classic of our summer skies. We look forward to this time of the year when we can go outside, our wish box under our arm, and let ourselves be lulled by the beauty of this meteor swarm.

Around mid-August, the Earth returns very close to the orbit of comet 109P / Swift-Tuttle, whose wake is strewn with billions of dust particles. But to be at the forefront of this shooting star festival, you will need to avoid any light pollution that could harm the show. Also the NASA recommends lying on the ground with your feet pointed northeast, and letting the magic work.

Aurore Boréale - Credit httpsunsplash.com@beckerworks


During an aurora borealis, the sky looks like the canvas of a great artist. As if, with each brushstroke, the painting comes to life, as if by magic. Is it a fairy tale story? No ! Rather, it’s a very scientific story.

According to canadian space agencyThe aurora borealis, also known as the polar aurora, is formed in the northern hemisphere when charged particles of electrons and protons collide with gases in the Earth’s upper atmosphere. These collisions generate tiny bursts of light that fill the sky with colorful light. Thus, billions of small bursts of light appear in sequence, giving the impression that the dawn is “dancing” in the sky.

THE MOON - Credit amit-talwar-zoz1tcV5KNc-unsplash


It would be at least 4.51 billion years old. It is part of our nocturnal decor. Without it, the sky would not be the same. Who am I ? The Moon of course!

However, some phases of the Moon are more fascinating than others. Especially when it comes to the super moon! Even though this name evokes that of a superhero, the term has been a real craze since 2010. We talk about a super moon on a new moon or a full moon, and when it is closest to the Earth, or at its perigee. It will then appear up to 14% larger and 30% brighter than usual NASA. One thing is for sure, when this happens, take the time to admire her and tell her your secrets.

A STEVE light captured at Childs Lake, Manitoba.  Credit NASA's Goddard Space Flight CenterKrista Trinder


Have you ever seen a Steve? I am not talking about your neighbor, but about a phenomenon similar to the aurora borealis. Steve is a purple and green celestial ribbon that stretches for several hundred kilometers, and follows an east-west alignment. Its name, recognized since 2018 by the NASA, is the acronym for “Strong Thermal Emission Velocity Enhancement”, or “sharp increase in the rate of thermal emission”.

The particular aspect of Steve fascinates the scientific community which has difficulty in finding an explanation. But according to researchers from the the University of Calgary in Canada, it could be a phenomenon which forms in the ionosphere, the layer of the atmosphere between 60 km to 1000 km of altitude. Steve’s ions would move faster and be hotter (around 3,000 ° C) than other particles in the same area.

The Milky Way - Credit m-wrona-opaAhLe0ZTI-unsplash


In English, the Milky Way is called Milky Way. A name that I find delicious and which perfectly represents this species of whitish band that can easily be observed at night.

According to NASA, our galaxy, the Milky Way in which our Solar System is located, is made up of gas, dust and stars. As you gaze at the Milky Way, you gaze at nearly 1.7 billion stars. Know that it would take you more than 50 years to count them all, at the rate of one per second. Our Milky Way is about 100,000 light years across and about 20,000 light years thick. Like most galaxies, the Milky Way spins slowly, just like us. A complete rotation lasts about 240 million years. Since our sun was born about 4.6 billion years ago, we have completed more than 19 rotations around the center of our galaxy.


You can continue your exploration of the cosmos by visiting the following sites:


Montreal Planetarium

The ASTROLab of Mont-Mégantic

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