Fernando Alcoforado*
This article aims to describe the threats to life on Earth come from space. Cosmologists consider that the Universe emerged with the “Big Bang” around 13.3 to 13.9 billion years ago and planet Earth about 4.6 billion years ago, and for a long time remained an environment inhospitable. The Earth formed from the disk of gas and dust that formed the Sun and the other bodies of the solar system. It is important to note that the Moon formed about 100 million years after Earth after suffering a violent impact from a Mars-sized body called Theia. The huge impact tore off part of the Earth, which was then a magma sphere, and put it into Earth orbit. The fragments that resulted from the clash between Terra and Theia formed the Moon.
The newly created Earth-Moon system began to exert a mutual gravitational pull. Such attraction has produced (and continues to produce) the dissipation of an enormous amount of energy resulting from the friction of the oceans with the seaflows during the ebb and flow of the tides. As a result of this dissipation, the Earth’s rotation speed has slowed from about 6 hours from the earliest moonless Earth day to the current 24 hours. Today the Moon continues to curb the rotation of the earth at a rate of about 1.5 milliseconds every century. To compensate for this decrease in the Earth’s rotation speed, the lunar rotation energy needs to increase which produces a Moon’s move away from Earth at a speed of about 3.82 centimeters each year (STACEY, F.D. Physics of the Earth, John Willey & Sons, 1969).
The increased distance from the Moon to the Earth is due to the friction between the Earth’s surface and the huge body of water that is on it and, over time, the earth rotates a little more slowly about its axis. Earth and Moon are united by a kind of gravitational hug. Then, as the movement of the Earth slows, that of the Moon accelerates. And when something in orbit accelerates, that acceleration pushes it outward. For every action there is an equal and opposite reaction according to Newton’s third law. The distance from the Moon affects our planet in many ways. To begin with, as the Earth spins slower, the days get longer. They get longer, by two thousandths of a second every century.
What would happen to Earth if the Moon continually drifted away? It would be catastrophic for planet Earth because the days could be 48 times longer. At night, temperatures would kill everyone with cold. Throughout the day no one could stand the heat. On the coast, there would be violent winds of 200 km / h. In terms of life there would be almost nothing left but super-resistant bacteria and worms. All of this shows how the Earth is dependent on this sterile ball of minerals we call the Moon. Just to give you an idea, before the Moon began to orbit our planet, one day last anywhere between six and eight hours. Since then, interaction with the Moon has slowed the rotation of the planet. By celestial mechanics, this happens as the Moon moves away.
More than 4 billion years ago, it is estimated that the Moon was only 25,000 kilometers from Earth. Today the distance is 15 times greater. With the Moon’s move away from Earth, the planet’s speed of rotation gradually slowed. By about 3 billion years, the length of the day had already jumped to 18 hours. Following this trend, the prevailing 24-hour day today will not last forever. The Moon will continue to distance now, at a faster rate than before, at a rate of 3.8 centimeters per year. This process should continue until the satellite is 560,000 kilometers away. When this occurs, the rotation of the earth will stabilize, the days will be 1,152 hours, and life on the planet will be unviable. This process will take at least 4 billion years to happen. In this chaotic scenario is unlikely to have humans witnessing it because in the next billion years, the Sun will be 10% warmer enough to make any form of life on Earth impossible.
The main consequences of the sudden disappearance of the Moon would be: 1) the disappearance of the tidal phenomenon; 2) the end of the stability of the Earth’s axis of rotation; 3) the end of many terrestrial species and plants; and 4) drastic and global climate change resulting from the disappearance of tides and the destabilization of the earth’s axis of rotation. The disappearance of the tidal phenomenon resulting from the gravity of the moon would lead to the weakening of ocean currents whose waters would tend to stagnate. The shores of the seas would lose their drainage and natural cleansing system due to the advance and retreat of the waters. Ocean water would tend to redistribute, heading towards the poles, and sea level would rise on the coasts. The consequence of all this would be a drastic change in the Earth’s climate.
The end of the Earth’s axis of rotation stability would occur with Earth’s precession that would slow down without the Moon, like when a spinning top begins to sway and its axis can chaotically vary between 0 and 90 degrees. The Earth’s axis of rotation is 23 degrees from the plane of its orbit caused by the orbital motion of the moon that is responsible for the existence of the stations as we know them. The end of the Earth’s axis of rotation stability would result in global scale climate change, which could produce summers with temperatures exceeding 100 degrees, and winters with temperatures below minus 80 degrees. In the most extreme case, the Earth’s axis of rotation could align directly towards the Sun, which would cause areas of the planet to be under constant sunstroke and others in permanent obscurity. The gigantic thermal differences between one half and the other of the Earth would cause extreme winds with speeds of over 300 kilometers per hour and other dramatic weather phenomena.
The end of many terrestrial species and plants would occur with the disappearance of the Moon that would also affect life on Earth. The most immediate effect would be the disappearance of the Moon’s own sunlight, which would alter the biological rhythms of many animal and plant species that have adapted and evolved under the cyclic presence of lunar light. Many species would suddenly have to adapt to the total darkness of moonless nights. The disappearance of lunar tides would particularly affect species adapted to marine flows and currents, such as those living on the coasts where tidal flows carry nutrients, or those inhabiting seas and oceans accustomed to current patterns of marine currents.
Drastic and global climate change resulting from the disappearance of the tides and the destabilization of the Earth’s axis of rotation would be the factors that would produce the most dire consequences for terrestrial life. The vital rhythms of all animal and plant species would be altered by these climate changes: migrations, the time of mating, hibernation. Plant growth would also be affected by extreme thermal variations. Many species would be unable to adapt, there would be massive extinction of plants and animals. In the very extreme case, which we saw earlier, that the Earth’s axis of rotation would eventually point to the sun, life on earth as we know it would be impossible in either hemisphere, and perhaps only viable on the equator, between the hot and ice hemispheres of the planet.
One of humanity’s greatest fears is that the Earth is on a collision course with some giant asteroid that has the potential to completely annihilate us. Fear is by no means unfounded because these monsters exist in space and can strike Earth. In fact, the history of our planet is full of these impacts. While still in formation, the Earth was bombarded more often. According to NASA’s Jet Propulsion Laboratory, 556 small asteroids crossed the atmosphere from 1994 to 2013. Most of them disintegrate, but some can reach the surface and wreak havoc, such as the object that struck the city of Chelyabinsk, in Russia [OLIVEIRA, André Jorge. Veja o que aconteceria se um asteroide de 500 quilômetros de diâmetro atingisse a Terra (See what would happen if a 500-kilometer diameter asteroid hit Earth). Available on the website <https://revistagalileu.globo.com/Ciencia/Espaco/noticia/2015/03/veja-o-que-aconteceria-se-um-asteroide-de-500-quilometros-de-diametro-atingisse-terra.html>). One must not forget that the dinosaur extermination occurred between 208 and 144 million years ago due to an impact of a 10 km diameter asteroid that generated an explosion similar to 100 trillion tons of TNT.
Oliveira asks: What would happen to our planet if it collided with a really large asteroid? Discovery Channel has made a simulation that answers this question. The video shows a 500-kilometer asteroid (almost the distance from Sao Paulo to Belo Horizonte) crashing into the Pacific Ocean and producing shockwaves that travel at hypersonic speeds. Such an episode would decree the end of life on earth. The force of the impact would be such that it would completely rupture the region’s earth’s crust, sending debris into space. They would enter a low orbit and, as they fell, would destroy the entire surface. As if the scenario wasn’t catastrophic enough, the destruction doesn’t stop there: a firestorm would spread through the atmosphere and vaporize any life in its path. In just one day, the entire planet would become uninhabitable. Most shocking of all is how often scientists believe such an apocalypse has struck the earth throughout its history, that is six times.
Another threat from space concerns the explosions of supernovae, stars of greater mass than our Sun, at the end of their existence that could wipe out life on Earth due to the release of enough gamma and x-ray radiation to heat the surface of our planet and make the atmosphere and oceans evaporate. In addition to the threats posed by the Moon’s move away from Earth, the collision with an asteroid and supernova star bursts, it is scientifically known that all life on Earth will be swept away when our Sun comes to an end within 5 billion years by becoming a red giant that will swallow the earth. Finally, the Universe will become incapable of allowing any kind of life to exist because of its eternal expansion, leaving only residual heat and black holes, or else it will contract again by uniting all matter and energy into one great black hole that is a region of space with a gravitational field so intense due to the death of supermassive stars where intense gravity compresses matter until there is no more space between atoms that not even light can escape from within it. Either way, all life in the Universe will disappear forever. This means that we will face the death of our species with the disappearance of the Sun, the Earth and the Universe itself.
In astronomy, the most recent discovery has been that the Universe is made up of 73% dark matter and 23% dark energy, while the rest is made up of galaxies, stars, planets, etc. which corresponds to 4% of the entire universe (PANEK, Richard. The 4% Universe. Boston e New York: Mariner Books, 2011). The hypothesis of dark matter and dark energy is a recent cosmological model, which came into play to break the paradigm related to the standard cosmological model, since several observational results pointed to a major prediction flaw based on this model. The first of the two hypotheses to emerge was that of dark matter, with Fritz Zwicky in 1933. From their results, the speed of galaxies was such that their gravitational pull, calculated from their visible mass, was insufficient to form a system turned on as it was observed. Zwicky then proposed that there was a portion of extra matter that was not visible: “dark matter”.
In 1970, a group of astronomers, led by astronomer Vera Rubin, made a series of very precise measurements that shook the previous cosmological theoretical structures once and for all. These measurements indicated that the velocity of rotation in the galaxies, from a certain point, was approximately constant and did not decrease with the inverse square root of the ray, as predicted by Newtonian physics. So the idea of dark matter came up with more vigor and seriousness, being a frontier research these days. In the 1990s, two independent teams of astrophysicists turned their eyes to distant supernovae (named after the celestial bodies arising from the explosions of stars with more than 10 solar masses, which produce extremely bright objects that decline to invisibility, past a few weeks or months) to calculate the slowdown. To their surprise, they found that the expansion of the universe was not slowing but accelerating. Something must be overcoming the force of gravity, which is a consequence of a new form of matter that scientists have called “dark energy” that has not been detected so far and current theory cannot explain. Dark matter attracts and dark energy repels, that is, dark matter is used to explain a greater than expected gravitational attraction, while dark energy is used to explain a negative gravitational attraction.
On the issue of energy and dark matter, there is the new fact that Dark Energy would be eating Dark Matter. This means that space can become emptier. A tempting suggestion that dark matter may be slowly shifting to dark energy was discovered by a team of cosmologists in the UK and Italy. While the specific nature of the interaction that drives conversion is not known, the process could be responsible for slowing the growth of galaxies and other large-scale structures in the universe over the past eight billion years. If the conversion continues at the current pace, the ultimate fate of the universe as a cold, dark and empty place could come sooner than expected. Cosmologists Valentina Salvatelli, Najla Said and Alessandro Melchiorri of the University of Rome, together with David Wands and Marco Bruni at the University of Portsmouth reported that the conversion of dark matter into dark energy is very slow [BACHEGA, Riis. A Energia Escura está comendo a Matéria Escura? (Dark Energy is eating Dark Matter?). Available on the website <http://www.universoracionalista.org/a-energia-escura-esta-comendo-a-materia-escura/>). If it continues at its current rate, the entire Universe will have fallen into dark energy in about 100 billion years. If dark energy is growing and dark matter is evaporating, we will end up with a large and empty Universe with almost nothing in it.
From the foregoing, it appears that the increased distance from the Moon to the Earth, the collision of the earth with a giant asteroid, the explosions of supernova stars, the end of the sun’s existence and the ultimate fate of the universe as a cold place, dark and empty are major threats to life on Earth from space. It can be said that these threats should not be the object of immediate concern for humanity because they will not occur in the short term but billions of years into the future. However, one fact is evident: the future of humanity is at stake that imposes the need to stablish a survival strategy in the face of the threats outlined above, especially to counter the collision caused by giant asteroids. The threats from space require humanity to unite in a common effort to build a solidary human society to meet this great challenge that requires the establishment of a world government to meet the great challenges of humanity in the 21st century, which consist of: 1) chain economic and financial crises; 2) social revolutions and counterrevolutions worldwide; 3) cascade wars; 4) world overpopulation; 5) deadly pandemic; 6) extreme climate change; and 7) organized crime whose global actions to address them are impossible to take forward by individual national states and current international organizations.
* Fernando Alcoforado, 79, awarded the medal of Engineering Merit of the CONFEA / CREA System, member of the Bahia Academy of Education, engineer and doctor in Territorial Planning and Regional Development by the University of Barcelona, university professor and consultant in the areas of strategic planning, business planning, regional planning and planning of energy systems, is author of the books Globalização (Editora Nobel, São Paulo, 1997), De Collor a FHC- O Brasil e a Nova (Des)ordem Mundial (Editora Nobel, São Paulo, 1998), Um Projeto para o Brasil (Editora Nobel, São Paulo, 2000), Os condicionantes do desenvolvimento do Estado da Bahia (Tese de doutorado. Universidade de Barcelona,http://www.tesisenred.net/handle/10803/1944, 2003), Globalização e Desenvolvimento (Editora Nobel, São Paulo, 2006), Bahia- Desenvolvimento do Século XVI ao Século XX e Objetivos Estratégicos na Era Contemporânea (EGBA, Salvador, 2008), The Necessary Conditions of the Economic and Social Development- The Case of the State of Bahia (VDM Verlag Dr. Müller Aktiengesellschaft & Co. KG, Saarbrücken, Germany, 2010), Aquecimento Global e Catástrofe Planetária (Viena- Editora e Gráfica, Santa Cruz do Rio Pardo, São Paulo, 2010), Amazônia Sustentável- Para o progresso do Brasil e combate ao aquecimento global (Viena- Editora e Gráfica, Santa Cruz do Rio Pardo, São Paulo, 2011), Os Fatores Condicionantes do Desenvolvimento Econômico e Social (Editora CRV, Curitiba, 2012), Energia no Mundo e no Brasil- Energia e Mudança Climática Catastrófica no Século XXI (Editora CRV, Curitiba, 2015), As Grandes Revoluções Científicas, Econômicas e Sociais que Mudaram o Mundo (Editora CRV, Curitiba, 2016), A Invenção de um novo Brasil (Editora CRV, Curitiba, 2017), Esquerda x Direita e a sua convergência (Associação Baiana de Imprensa, Salvador, 2018, em co-autoria) and Como inventar o futuro para mudar o mundo (Editora CRV, Curitiba, 2019).
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