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But why are the planets of the solar system on the same plane?

When you see a model showing our solar system, all of the planets, and even asteroids, orbit at roughly the same plane. With all the space around the Sun, one might wonder why this is the case.

The explanation for this phenomenon can be found by going back in time to the very formation of the solar system, that is, 4.5 billion years ago. As Nader Haghighipour, an astronomer at the University of Hawaii at Manoa, explains, the solar system at that time was just a massive cloud of spinning dust and gas. This cloud had a diameter of about 12,000 astronomical units (AU), one AU corresponding to the distance between the Earth and the Sun, or roughly 150 million kilometers.

According to the researcher, the cloud kept growing and eventually collapsed on itself and contracted due to its own mass. At the same time, the cloud of dust and gas flattened like a pizza dough being tossed and whirled in the air.

The formation of the Sun

Unlike pizza dough, in the middle of the swirling cloud, the gas molecules clumped together until their temperature rose significantly. With the high temperature and pressure, the hydrogen atoms began to coalesce to form helium, and this activated the nuclear reaction that will last for billions of years. It is about the formation of the Sun.

Over the next 50 million years, the Sun continued to grow, collecting gas and dust from its surroundings, and ejecting intense heat waves and radiation. Gradually, an empty space began to form around him.

Around the planets and asteroids

Haghighipour explains that as the Sun grew, the cloud continued to collapse and form a disc around the star. This disc became increasingly flat and continued to expand with the Sun at its center. At some point it became what is called a protoplanetary disk.

For tens of millions of years, the dust particles in this protoplanetary disc swirled gently, and sometimes collided with each other. Some got stuck, and after a while the particles became grains, then the grains became pebbles of the order of a centimeter.

At some point, all of the material on the disc clumped together to form massive objects. Some of these objects grew so large that gravity eventually shaped them into spheres, forming planets, dwarf planets, and moons. Other objects took a more irregular shape and we were able to obtain asteroids, comets, or even certain small satellites.

The point is that all these objects formed from the protoplanetary disk have remained on one plane all this time. This is why we now have this configuration.

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Will the 2021 Nobel Peace Prize be awarded to Greta Thunberg?

The Nobel Peace Prize will announce, on October 8, who will be nominated in 2021. The climate issue being at the heart of global concerns, the young Greta Thunberg could be the new distinguished personality.

If Greta Thunberg were to become the Nobel Peace Prize winner, she would be, at 18, the second youngest distinguished (only a few months old), after Pakistani Malala Yousafzai.
If Greta Thunberg were to become the Nobel Peace Prize winner, she would be, at 18, the second youngest distinguished (only a few months old), after Pakistani Malala Yousafzai. | MIGUEL MEDINA / AFPWest FrancePublished on 02/10/2021 at 1:29

« It’s less hot in hell »: on Friday, hundreds of young people marched through the center of Milan, behind Swedish activist Greta Thunberg , demanding rapid action for the climate one month before the crucial COP26 conference in Glasgow . This week again, the young Swedish activist hit the mark with her scathing resignation and unwavering determination for the planet.

In just three weeks, the Nobel Peace Prize will be announced, just before Cop26. A crucial meeting which, according to many scientists, could determine the future of the planet. With this major deadline approaching, price watchers may well distinguish Greta Thunberg this year.

Who will receive the world’s most prestigious honor in 2021 will be unveiled on October 8. If this remains, each time, a total surprise, the prognoses are well underway and the committee carefully examines the global issues before selecting the recipient. With the COP26 climate summit set for early November in Scotland, the issue of the environment and the climate emergency could be at the heart of the committee’s concerns.

If Greta Thunberg were to become the Nobel Peace Prize winner, she would be, at 18, the second youngest distinguished (only a few months old), after Pakistani Malala Yousafzai.

“The committee often wants to send a message. And that would be a strong message to send to COP26, which will take place between the announcement of the award and the ceremony, ” Dan Smith, director of the Stockholm International Peace Research Institute told Reuters.

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Why NASA is looking for candidates to simulate life on Mars

Do you dream of living on Mars? Then this mission is for you. NASA is looking for volunteers to simulate life on the Red Planet. The US Space Agency is already planning for a possible manned flight to Mars in a few decades. 

NASA has just launched a somewhat special call for applications: it is recruiting volunteers to simulate life on Mars. They will live for a year in a 150-square-meter prefab, housed in the US Space Agency’s center in Texas. The objective: to test the physical and psychological challenges that would be faced by astronauts on a mission on the Red Planet.

« Testing interactions between people left to their own devices »

How much water, carbon dioxide or food is needed for a trip to Mars? How much waste is produced? These are the main questions for NASA. For Michel Viso, specialist in astrobiology, joined by Europe 1, the American Space Agency needs « to test the interactions between people left on their own ».

To apply, there are still some conditions. You must be between 30 and 55 years old, American nationality and a degree in mathematics, physics or engineering. The four successful candidates will live independently for one year. They will only communicate with each other or with robots.

Measure needs to the nearest gram

Even if a real expedition to the red planet is not on the agenda for the moment, this simulation remains an important step. « It is necessary to start now to calculate a certain number of things under real operational conditions », assures Michel Viso. Before specifying: « if we are short of oxygen or short of water on Mars, there will be a real problem! »

Measuring requirements to the nearest gram also serves to minimize the cost of future missions. They require large financial investments. And especially time: space agencies do not plan human space flights to Mars before 2040.

Source : Europe 1

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how was the earth formed?

The Earth formed when gravity attracted swirling gases and dust to become the third planet from the Sun,

A mixture of swirling gas and dust

About 4.5 billion years ago, the Solar System gradually adopted this arrangement that we know today. At this time, an interstellar molecular cloud collapsed, composing the Sun at its center. Around, a disk of gas and dust appeared.  » The Earth formed when gravity attracted swirling gases and dust to become the third planet from the Sun,  » observes  NASA on its website. Each planet in the Solar System has formed with a mixture of its own. But where does this dust come from which finally condensed to give our planet?

According to a study published at the end of 2019 in the journal Nature Astronomy and relayed on the Sciences et Avenir website, it would come in part from red giants, old stars which have already burned their hydrogen, as will be the case for our star within 4 to 5 billion years. To achieve this result, the researchers performed measurements of the abundance of palladium. This element, which is formed during the process of « slow neutron capture » taking place in the hearts of red giants, was remarkably present in our planet. The latter therefore inherited, in « its mixture », dust from one of these old stars. In general, stars disperse throughout their life or at the end, thanks to stellar winds, by exploding, or even by merging, chemical elements which are the building blocks of matter.

And the Moon in all of this?

According to the theory most accepted by the scientific community, that of the « giant impact », the Moon was created around 4.5 billion years ago when the primitive Earth was violently struck by a celestial body named Théia (mother of the Moon, Selene, in Greek mythology). The proto-planet was as massive as the planet Mars and the shock was tremendously violent. It vaporized Théia and a large part of the earth’s crust and mantle, poor in metals. Part of the cloud of vaporized rocks would have aggregated to Earth again, while the other part would have solidified not far away, giving rise to our satellite. 

Problem: the lunar subsoil is richer in metals than the portions of Earth excavated by Théia. This fact has long been known to scientists who are looking for an explanation. But a new study relayed by Sciences et Avenir in 2020indicates that there are still more metals than imagined which makes it even more difficult to interpret this shift while preserving the hypothesis of the giant impact. The study’s authors suggest that the collision between Theia and Terra was more violent and devastating than expected, and propelled deeper sections of the planet into orbit, including chunks of cores much richer in metals. Unless the collision happened much earlier when the Earth was still a ball covered in molten magma. Other theories exist to explain the formation of the Moon, some call for  a series of impacts  and others even believe that our satellite is  older than the Earth. ! Further investigations will still be necessary to settle this thorny debate.

With Sciences et Avenir

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What would life be like on Earth if it were flat?

Many people still think of the Earth as flat. They might change their mind if they realized the ways that would make life on a flat planet strange.

What would life be like on Earth if it were flat?
What would life be like on a flat earth? Photo credit: Shutterstock / AuntSpray

We live on a spherical planet, slightly flattened at the poles. The shape of the Earth should no longer be debated, as science has confirmed it time and time again. Despite this, there are still people who believe that we are living on a huge record . Researchers have already carried out work to show how ridiculous a flat planet would be. Here are a few.

No gravity on a flat earth

Gravity as we know it would change dramatically. On a spherical planet, it is the same for all objects, no matter where they are on the surface. A flat Earth would have no gravity , and a disk-shaped planet would not be possible under actual gravity conditions, according to the calculations of mathematician and physicist James Clerk Maxwell in the

What would life be like on Earth if it were flat?

An absence of atmosphere

Without gravity , a flat Earth could not have an atmosphere. It is the force of gravity that keeps this veil around our planet. And without this protective blanket, all life forms would be exposed to the void of space. This would lead to asphyxiation within seconds, zoologist Luis Villazon wrote in BBC Science Focus magazine. In addition, the water would evaporate in the void of space. The surface temperature would also drop, causing the remaining water to freeze quickly.

Water at the center of the planetary disk

If the Earth were a huge disk, the geographic North Pole would be in the middle of the disk. The existence of gravity would cause him to concentrate at this point. Precipitation would also gravitate towards this point. The further away from the center, the more horizontal the precipitation would be. Water from rivers and oceans also collects in the center of the huge structure, according to the Lamont-Doherty Earth Observatory at Columbia University in the United States.


GPS would not exist. It would indeed be difficult to put satellites into orbit around a flat planet . “  There are a number of satellite missions that society depends on that just wouldn’t work,  ” said James David , a geophysicist at the Lamont-Doherty Earth Observatory.

Much more trying trips

The trips would be much longer and more trying. Traveling on a spherical planet is much more convenient than on a large disk.

An absence of magnetosphere

On a flat Earth, without a solid core to generate a magnetic field , the protective layer that is the magnetosphere would cease to exist. We could no longer admire the Northern Lights. Most worrying is that we would be unprotected against solar radiation.READ ALSO:   According to this (conspiratorial) theory Trump would be an immortal alien who voluntarily contracted Covid-19

A difficulty for astronomical observations

The starry nights would be the same regardless of the observation point on a disc planet. Humanity would then miss many astronomical discoveries.

No storms

The devastating rotating nature of tropical storms stems from the Coriolis effect of the spherical Earth. Storms in the northern hemisphere rotate clockwise and those in the southern hemisphere counterclockwise. However, on a flat, stationary planet, no Coriolis effect would be generated. The absence of this effect means the absence of hurricanes, typhoons and cyclones.

Source : Neozone

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Demographic collapse: « the greatest risk for the future of civilization » according to Elon Musk

The CEO of Tesla is really worried about the demographic decline of the planet. While population growth has never been lower in the United States, the billionaire warns that the population collapse could really threaten the future of humanity, not only on Earth… but also on Mars!

The Wall Street Journal recently published an article on the decline of the American population : it turns out that as of July 1, 2020, the total population of the United States had only increased by 0.35%, the rate of lowest growth ever recorded across the Atlantic. And for good reason: in 2020, due to the COVID-19 pandemic , the number of deaths exceeded the number of births in half of the states.

Indeed, in the United States as in all developed countries, the fertility rate has been falling for several years; the economic uncertainty associated with the pandemic has only reinforced the trend. The subject appears to worry Elon Musk , who shared the Wall Street Journal article on his Twitter account . “ Population collapse is a much bigger problem than people realize, ” he tweeted a few days ago.

23 countries are expected to see their populations decline by more than 50% by 2100

According to INSEE , the French population increased by 0.3% in 2020, a weak growth which is again explained by the increase in deaths due to the pandemic. The fertility rate, which now stands at 1.84 children per woman, has been falling since 2015. According to the National Institute for Demographic Studies, we were 7 billion inhabitants on Earth in 2011, and will be 8 billion in 2022 or 2023. However, it is possible that this demographic explosion will end sooner than we think.

A study published in 2020 predicted a marked slowdown in population growth: after peaking at 9.7 billion people in 2064, the population is expected to decline to 8.8 billion in 2100. “ Continued global population growth during the century is no longer the most likely trajectory for the world’s population , ”said Dr Christopher Murray, director of the Institute for Health Metrics and Evaluation , which led the research. Also according to this study, in 2050, 151 countries should have a fertility rate below the generation replacement threshold; In addition, 23 countries, including Japan, Thailand and Spain, are expected to see their populations decline by more than 50% between 2017 and 2100.

While some climate specialists may be delighted with these forecasts, believing that a decline in the world population is one of the pivots that could make it possible to fight effectively against the climate crisis, demographers are, on the other hand, very worried about the economic future. the world – and in particular here, the United States: indeed, a decrease in the working-age population could end up plunging the country into a lasting economic crisis, implying a notable rise in inflation.

Elon Musk says he’s worried not only about the future of Earth, but Mars as well. The businessman fears that the decline of the world population will harm his project of « interplanetary conquest »:  » Mars has a great need for people, since the population is currently zero. Humans are the guardians of another life on Earth. Let’s bring life to Mars! « , He declared on his Twitter account. Musk sees this demographic decline as a major problem, adding that there is now a greater chance that our civilization will end up « in a groan » than in a « bang ».

Fewer young workers to innovate and support seniors

According to forecasts, by 2100, almost all countries (183 out of 195) will have a fertility rate below the generation replacement threshold (which is 2.1 births per woman). Fertility rates have already been falling all over the world since 1950; Europe, as well as Brazil and China, have already fallen below the replacement threshold.  » The only zone where fertility rates are maintained is the intertropical zone between the Sahel and the Zambezi « , specifies Hervé Le Bras , researcher at the National Institute of Demographic Studies.

The birth rate remains high in sub-Saharan Africa: there are more than seven children per woman in Niger. In these countries, in the past, infant mortality was compensated by a high birth rate; but today, the situation has changed: advances in medicine and the education of young girls are gradually reducing fertility. While the decline will not be as rapid in this part of the world as in the developed countries – with falling death rates and increasing numbers of women of childbearing age – it will eventually occur.

The main problem associated with the declining birth rate is the aging of the population. And there will be fewer and fewer young workers to take care of these elderly people financially … In addition, fewer workers are also less potential to innovate and develop new technologies that could improve our living conditions and save the planet.

In this context, several developed countries, in Europe, America and South-East Asia, will undoubtedly have to call on migrants to increase their working population – a solution which unfortunately causes a lot of societal tensions. Some countries, such as Russia, have already put in place birth policies based on financial support; Iran has adopted more drastic measures , restricting access to contraception and abortion.

Is humanity really threatened with extinction? For some researchers, the decline of the population remains one scenario among others, which is based on hypotheses of fertility, mortality and migratory phenomena which could vary over the years. For others, the trend is inevitable: “ We cannot continue like this in the next century, otherwise, at the end of the day, there will be no one on Earth. At one point or another, we will have to find a solution, ”warns Christopher Murray.

Source: Trust my Science

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What if the Earth suddenly stops spinning?

what would happen if the earth suddenly stopped turning

Current astrophysical models describe the formation of planets from rotating circumstellar discs. This rotational motion is then transmitted to the forming protoplanet by virtue of the conservation of angular momentum. All planets are therefore supposed to rotate, and Earth is no exception. But what if, suddenly, our planet stops spinning?

If the rotation stopped, the angular momentum of every object on Earth would tear its surface, which would be a disaster. However, as James Zimbelman, a geologist at the Smithsonian’s National Air and Space Museum , recalls , there is no natural force that would prevent the Earth from rotating. This is partly why our planet has been spinning since its formation.

The Earth rotates fully on its axis every 23 hours, 56 minutes and 4.09053 seconds. This results in the equator moving at around 1,770 km / h, with the rotational speed decreasing to zero at the poles, according to Zimbelman. If the planet were to come to a sudden stop, the angular momentum transmitted to air, water and even rocks along the equator would continue to move at this speed of 1,770 km / h. The movement would scour the surface while tearing it apart and sending shards to the upper regions of the atmosphere and space.

Linear momentum is the product of an object’s mass and its speed (direction and speed). A passenger in a moving car that comes to an abrupt stop will continue to move forward due to linear momentum. Angular momentum is a rotational analogue of linear momentum. It is the product of the moment of inertia (the rotational force required to rotate the mass) and the angular velocity. One of the fundamental principles of physics is the conservation of angular momentum. Once something turns, you have to exert the same force in the opposite direction to keep it from turning.

A chaotic situation for Earth

According to Zimbelman, the pieces that broke off the surface would regain some rotation as the Earth and its remnants continued on their way around the Sun. Eventually, the planet’s gravitational pull would bring back the halo of fragments with an unexpected effect. “ What Isaac Newton helped us understand with classical mechanics is that parts that accumulate and come together release some of their own energy in the form of heat, ” Zimbelman says.

The remains that ended up in the far reaches of the atmosphere and outer space would be attracted to the surface by the planet’s gravitational pull, and they would release energy on impact. The constant bombardment of these lumps would liquefy the crust into an ocean of molten rock, Zimbelman explains. Eventually, the colliding fragments would be reabsorbed back into the molten sea through a process called accretion.

The rapid and destructive transition would also vaporize most of the water on the planet’s surface. While most of this vaporized water would be wasted, some could be incorporated into newly solidified minerals, like olivine. Finally, all the fragments would not be reabsorbed by accretion. Some of the planetary pieces would be swept away by the Moon’s gravitational pull, bombarding the nearby satellite and creating countless more craters on its surface.

Source : Trust my Science

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How was the moon born?

During lunar eclipses, when the Earth interposes itself exactly between it and the Sun, the Moon turns reddish due to the scattering of red light by the Earth's atmosphere (Ph. Jonathan Leung via Flickr CC BY 2.0)

It was a huge cataclysm that gave birth to it! At least, scientists are sure. Even if they struggle to understand in detail how our satellite was born.

At the origin of everything, there was therefore a spectacular clash between the primitive Earth and a planetary embryo the size of Mars. Debris from the impactor and a fraction of the Earth’s mantle were thrown into orbit before coming together to form the Moon. This scenario, known as the giant impact, was established in 2004 thanks to numerical simulations carried out by Robin Canup, of the University of Boulder (United States).

Contrary to the hypothesis of gravitational capture or that of a fission of a piece of young Earth, it is the only one capable of accounting for the current dynamics of the Earth-Moon system.

But this scenario implies that the Moon should be composed of a mixture of 80% of the impactor and 20% of the Earth’s mantle, while we observe a strict geochemical similarity between the two stars!


Three hypotheses are now proposed to resolve this inconsistency. For Matija Cuk, of the Seti Institute (United States), and Sarah Stewart, of Harvard, it is enough to modify the speed of rotation of the Earth on itself at the moment of the impact with a planet of half of the mass of Mars to generate a Moon composed of 92% of terrestrial materials.

For Robin Canup, we must imagine an impactor of the mass of the Earth, producing a phenomenal cataclysm capable of mixing the materials of the young Earth and the impactor in a homogeneous way.


As for Willy Benz, from the University of Bern (Switzerland), he suggests a conventional impactor (the size of Mars), but much faster than previously imagined, and colliding with a rapidly rotating Earth on its axis.  With this abundance of scenarios, specialists still do not know how the moon was formed.

Let us add that they also ignore when it started to shine in our night sky. At least, their response varies according to the dating methods used and the simulations carried out. Decidedly, the star of the night is not about to reveal all its mysteries …

Source : Science & Vie 

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After the Sun’s death, life could be reborn on Earth

The study, led by Dimitri Veras and published in Monthly Notices of the Royal Astronomical Society, sought to understand how the death of a star like our sun affects the planets around it, and any life that might be there.

White dwarfs are the final stage of many stars. When stars have no more hydrogen to merge in their nucleus, they transform into red giants burning helium. Red Giants are incredibly volatile, and emit raging solar winds that crush all nearby planets . Recently, it was the red giant Betelgeuse which had mysteriously lost its shine .

The study concludes that it is almost impossible for life to survive cataclysmic stellar evolution unless the planet has an intensely strong magnetic field, or magnetosphere, that can protect it from adverse effects.

Life could reappear on Earth after the Sun dies

In about five billion years, our sun’s core will contract and get hotter. And in response, its outer layers will swell and cool considerably. This will transform our star into a « red giant » with a diameter of tens of millions of kilometers which will engulf a few planets in our solar system .

Indeed, the orbits of planets and habitable zones are shifted during such a stellar phase. Some planets are swallowed up by the star’s expansion, while others are pushed back . Unfortunately, the habitable zone is pushed back faster than the planets, which means that a habitable planet could find itself deprived of protection and favorable conditions for life .

As a result, we now know that when the Sun dies, the Earth’s magnetic field may not be enough to protect it against a stronger solar wind and against changes in our star. In other words , it is therefore extremely unlikely that life on a planet could survive the death of its sun , but new life could be born from the ashes of the old one.

Indeed, once the star stops emitting strong solar winds by transforming into a white dwarf, the planets around could again create favorable conditions for the development of life. Eventually, however, all life around it could disappear, since it is known that the explosion of white dwarfs would be similar to that of nuclear weapons when stars die in supernovae .

Source: Live Science

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Elon Musk and Jeff Bezos, the billionaires who watch the Earth burn

SpaceX boss Elon Musk January 19, 2020.

THE MOOD OF THE DAY – Canada and West Virginia go up in smoke, Germany and China drown. And during this time, the big bosses play cosmonauts and dream of colonies on Mars …

All over the planet, trapped humans, engulfed by sudden floods, fleeing from mega-fire, annihilated by « heat domes ». We barely have time to take an interest in the fate of the Germans drowned in their homes that we have to run in a flooded subway in China, and return to Canada, which we had left below 50 degrees to witness the destruction by the West Virginia forest fire. The media are doing their job. Nothing is spared us, and we « know ». Absolutely nothing that happens to us was unpredictable, the best scientists on the planet, climatologists and oceanographers, brought together in the IPCC thirty years ago by Ronald Reagan and Margaret Thatcher, two not particularly visionary leaders, have perfectly planned the steps past the disaster, and tell us the following.

Getting laid between the rich

No future on Earth? We do not care ! They are smart, have created « disruptive » companies thanks to which they amass billions, and scramble to send the ultra-rich of the planet into the air, with rocket planes that we had the first. seen for a fortnight. Behind these flights with an exciting carbon footprint, two visions as crazy as the other, that we struggle to prioritize: Jeff Bezos, boss of Amazon, wants to build space colonies where millions of people could live and especially work Aboveground ; Tesla boss Elon Musk believes the last humans will live on Mars. They’ve already sorted it out. What is it called?

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