In October 2020, NASA announced with great fanfare that water had been discovered on the Moon. Neither one nor two, the press then seized on this information, distorting it at the same time.
Because NASA’s discoveries were still only preliminary. On the ground, space missions had to confirm the theories and other analyzes of the American space agency. Finally, after more than a year of waiting for the scientific community, it is finally, ironically, the Chinese competitor (CNSA) which with its Chang’e 5 probe has provided NASA with the precious answer.
How the water came to our nocturnal star ?
Now that the presence of water on the surface of the Moon is no longer lacking (or almost), the big question is to know how this water could end up there. According to CNSA scientists who deliver their conclusions in an article published in the journal Science Advances, water would have arrived on the Moon because of the solar wind.
In fact, hydrogen particles traveled to the heart of this stellar wind before coming to rest on the Moon. Once deposited on the surface of our satellite, the hydrogen met the oxygen there, thus forming molecules of water (H2O) and hydroxyl (OH). This idea had already been developed by NASA researchers in 2018 and 2020 when the American space agency found traces of water on the Moon.
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.
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.
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
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.
The starry nights would be the same regardless of the observation point on a disc planet. Humanity would then miss many astronomical discoveries.
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.
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.
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.
THE MYSTERY REMAINS
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 …
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.
When billionaire Jeff Bezos straps onto his company’s rocket capsule on July 20, he and his fellow travelers will be taking a calculated risk to their lives and physical integrity during their suborbital flight. Only 382 space flights have been launched from the United States, and four of them have ended catastrophically.
So the failure rate is around one in a hundred, which is much higher than that of commercial air transport, which is one in a million, or that of most other land-based activities, according to the. analysis by the Center for Space Policy and Strategy .
« Until we get a lot of experience, as we have done with millions of airplane flights over the years, there will be some learning, » said George Nield, co-author of the report, to Insider’s Morgan McFall-Johnsen. « With cars, boats, planes and trains, people die every year. And spaceflight will be no different in that regard. »
Work accidents are more numerous
But if you look at it another way, space flight accidents in the United States have claimed the lives of far fewer people than the number of people who die from work-related accidents. According to US labor statistics , approximately 5,000 workers die each year, while 15 astronauts have died in the history of US spaceflight. What’s more, of the 5,333 American workers who died in 2019 alone, more than 913 worked in the transportation and warehouse industry. In other words, if a person dies on the job, there is a high probability that they were driving a truck or working in a warehouse.
Across all sectors, more than half of worker fatalities are due to transportation incidents or slips, trips and falls. The rates of injury and non-fatal illness are naturally much higher. In 2019, there were about three incidents per 100 workers, in which one person suffered an illness or injury on the job that required at least one day of sick leave.
It’s difficult to make direct statistical comparisons between spaceflight and other activities, in part because the industry is still so new, which amplifies the risk. In addition, the Federal Civil Aviation Administration is not empowered to issue rules relating to the health and safety of participants in space flights.
Blue Origin’s New Shepard rocket has made 15 flights since 2015, including three successful tests of its emergency escape system that drops the passenger capsule in the event of a rocket failure. Jeff Bezos’ flight will be the spacecraft’s first flight with humans on board. Blue Origin’s approach to product development is « much less risky » than NASA’s space shuttle program, which had a full crew on its very first flight, said John Logsdon, founder of the Space Policy Institute from George Washington University and former NASA Advisory Board member to Morgan McFall-Johnsen.
Amazon wants to reduce workplace accidents
Meanwhile, on Earth, drivers for Amazon’s delivery partners have described how the delivery scheduling app sometimes asks them to cross multiple lanes of traffic, or they have to choose between filling quotas or driving safely. security.
One of Jeff Bezos’ latest actions as CEO was to highlight the problem the company is currently having with workplace injuries and to pledge to make Amazon « the safest place in the world to. to work ». In his letter to shareholders, Jeff Bezos said he would make workplace safety one of his main areas of focus in his continued role as executive chairman. The company will invest $ 300 million (around € 253 million in 2021 to halve workplace accidents by 2025, including a $ 66 million (around € 56 million) project to prevent accidents at work. collisions between forklifts and industrial vehicles.
“Jeff Bezos is a risk taker,” John Logsdon said. « He certainly understands that there are risks [in spaceflight], and probably has a good idea of the degree of risk. »
Once again, the Simpsons had accurately predicted a historic event.
On July 11, 2021, Richard Branson flew into space aboard the VSS Unity spacecraft, a dream for the one who founded Virgin Galactic almost 17 years ago for the purpose of space tourism. He thus became the first billionaire founder of such a company to travel himself beyond the limits of the Earth, before Jeff Bezos who is to fly next week with Blue Origin, and Elon Musk who would have booked a flight. at… Virgin Galactic.
This first excursion into space, the Simpsons had already imagined it… seven years ago, in 2014. That year, in an episode of season 25 called “The Art of War” , we could see a certain Richard Branson contemplating a painting from his spaceship. Seven years later, reality replicates this fictional image almost verbatim.
Well its been known Virgin Galactic has been trying to get Richard Branson into space for 17 of the 34 years The Simpsons have been on the air, so the show wasn’t exactly being Nostradamus here.
Even so, as this surfer points out above, the Simpsons’ prediction is not so surprising. “It’s well known that Virgin Galactic has been trying to send Richard Branson for 17 years. The Simpsons are not Nostradamus here, ”he explains.
Indeed, when the episode in question aired, Branson had already founded Virgin Galactic for a decade to serve this purpose. In the end, the Simpsons did nothing but anticipate a more than probable future… correctly, once again.
Climate change and this lunar « oscillation » are a dangerous combination for coastal cities, according to NASA.
NASA scientists say that an « oscillation » of the orbit of the moon will greatly worsen maritime flooding from the next decade. Research, carried out in collaboration with the University of Hawaii, shows that this lunar oscillation will cause an increase in the number of floods, which will considerably disrupt daily life and damage the infrastructure of coastal cities, accustomed to much more flooding. weak and less frequent.
A natural phenomenon, made dangerous by global warming
Live Science reminds us that the change in the Moon’s orbit is in fact a perfectly natural cycle, which has always taken place and will continue to occur long after our disappearance. The Moon’s orbit creates periods of high or low tides at a rate of about 18.6 years.null
But this time around, the phenomenon could turn out to be more dangerous due to rising sea levels, caused by the effects of global warming and uncontrolled greenhouse gas emissions. So when the next period of high tides begins in the early 2030s, the floods are sure to be much worse, longer and more dangerous than ever.
The element also called C / 2014 UN271 is about ten times larger and has a mass 1,000 times greater than that of the average comet. Scientists thus estimated that its diameter was between 100 and 200 kilometers. Specialists have struggled to make precise assessments because it is still extremely far from Earth.
Visible with very powerful instruments
To calculate its size, astronomers had to rely on the amount of sunlight it reflects. The object should however approach our planet and be closest to it in 2031. It will nevertheless remain at a distance of 11 astronomical units from the Blue Planet, or approximately 1.65 billion kilometers. Even as close as possible to the Earth, the comet will therefore only be visible with particularly powerful instruments.
In addition to its size and trajectory, C / 2014 UN271 stands out from other celestial elements by the rarity of its appearances in our internal solar system. Its last passage dates back to three million years ago, that is to say at the time when our planet was, among other things, populated by Australopithecines. The comet was born in the Oort cloud, to 40,000 astronomical units from the sun.
Never had a body come from so far away been spotted heading towards Earth. Scientists hope to learn a lot from the study of this celestial object, especially when it comes to the formation of massive celestial bodies and the movements of the planets.