User:VonTheGreater26/Geology course

Geology is the study of the earth's physical structure and composition, its history, and the processes that affect it.

Earth birth
Approximately 4.6 billion years ago, a disk-shaped cloud of dust and gas began circling the young Sun. Moreover, we know this because of the fossil record, one of the most straightforward methods for determining the age of our planet. Scientists have discovered zircon crystals that are approximately 4,300,000,000 years old! These crystals are the oldest materials discovered on our planet so far. How our planet developed, though, remains a scientific enigma. However, there are two main planetary formation ideas. Core accretion is the first and most widely recognized model. Our Sun was created from a solar nebula composed of whirling gas and dust particles some 4.6 billion years ago.

As the remaining debris of various sizes continued to orbit our star at varying speeds, it began to clash and adhere. Under the influence of gravity, smaller particles developed into larger particles with diameters ranging from hundreds to thousands of kilometers. The solar wind would then sweep away lighter components, such as hydrogen and helium, leaving only stony materials to form terrestrial planets. This process will continue until these space objects have thousands of kilometers. Nevertheless, at great distances from the star, the Sun's continual stream of charged particles has little effect on lighter materials. As a result, these components combine and turn into enormous gaseous bodies. Excitingly, NASA believes that if this is how planets develop, then small, rocky planets like Earth are more prevalent in the universe than gas-giant planets. The issue with this hypothesis is that it explains the genesis of terrestrial planets perfectly but has trouble with the production of gigantic worlds. Scientists estimate that the gaseous ring that encircled our Sun lasted no more than 4-5 million years.

Furthermore, simulations based on the core accretion model indicate that these planets form over a longer time. Nevertheless, the second theory, or the disk instability model, answers this problem. Earlier in the solar system's existence, according to this more recent theory, dust and gas clumped together. In time, these fragments gradually coalesce into a planet. In contrast to the core accretion concept, planets can form far faster in this scenario. This hypothesis predicts that it might occur within the next thousand years! This rate of planet formation makes it possible for these worlds to contain the rapidly dissipating lighter gases. Recent research indicates that the formation of the proto-Earth occurred roughly 5 million years ago.

Furthermore, it is nothing on a cosmic scale. If the solar system's projected 4.6 billion years were translated to 24 hours, these 5 million years would equal only 1.5 minutes. If scientists are correct, water could be a byproduct of the formation of an Earth-like planet. This would increase our likelihood of discovering the components of life outside of our solar system. What is our satellite's status? How did the Moon come into existence?

Moon formation
Numerous explanations have been offered by astronomers regarding the origin of our satellite. Some of them are extremely peculiar. According to the Fission Theory, the Moon was once a component of our planet! When the Earth was still a molten sphere, it may have ejected the material that today makes up our satellite. It would have been a stunning spectacle to witness, despite the skepticism of most scientists regarding the speed at which our world must have been rotating at the time. The Capture theory is yet another intriguing theory that proposes the Moon was captured from a separate region of the solar system. We already know that certain planets acquired their moons in this manner. Before our planet's gravity drew it, perhaps the Moon was orbiting Venus. However, this does not explain why Earth and the Moon have nearly identical oxygen and isotope ratios. However, the next theory might! Some scientists believe that our satellite was created alongside Earth. The theory is that both were produced at around the same time, from the same gas and dust, and in the same region of the protoplanetary disk of our solar system. Co-formation is an appropriate explanation due to the isotopic similarities between the two space objects. However, it cannot explain the variation in size between their iron cores. The dominant and possibly most mind-boggling explanation is that the Moon was created by a huge collision with another celestial body.

There is a possibility that another planet formed 150 million kilometers [93 million miles] from the Sun. The formation of the planet Theia may have accompanied Earth's formation. This otherworldly planet must have been smaller than ours, roughly the size and mass of Mars. Theia's orbit was initially stable, but its orbit became unstable as Earth accumulated more material and gained mass. Consequently, it swung back and forth toward Earth until the two protoplanets collided. Due to the moderate impact velocity, the Earth was not destroyed. However, the impact must have produced a disk of debris consisting of molten rock and hot gas, which became the Moon's constituent parts. Both Theia and the Earth may comprise a mixture of substances, and more of the particles with a lower density would eventually coalesce into the Moon. If this is the case, it explains why our planet has a denser and thicker core than our satellite and why the Earth and Moon orbit each other in the manner they do. However, let us return to Earth. During the subsequent 500 million years (Hadean Eon 4.5–4.0 billion years ago), the Earth resembled a ball of molten surface, volcanism, and asteroid collisions.

Moreover, other factors, including gravity compression, radioactive decay, and asteroid strikes, rendered it incredibly hot. A significant quantity of this early heat remains within the planet's interior. However, minerals began to crystallize when they cooled, and components of varying densities created the crust, mantle, and core. How then could water appear on a scorching, space-borne rock?

Origin of water
Oceans cover more than 70 percent of the Earth's surface. This is equivalent to 333 million miles cubic of surface water or ice. However, our planet has more liquid water than any other known rocky planet in our solar system is not entirely understood. As with the Earth and the Moon, there are multiple explanations regarding the origin of water on Titan. Extrasolar sources, such as comets, trans-Neptunian objects, and perhaps protoplanets, are a possible explanation. Water is abundant in our solar system. For example, two-thirds of Uranus and Neptune are composed of ice. If our planet was formed hot and dry, then frozen comets and asteroids must have transported water from elsewhere.

Comets are composed of dust and ice, most of which is frozen water. Therefore, these may be the clue. However, tests indicate that comet water contains significantly more deuterium than water on Earth. What is up with asteroids? Because their ratio of deuterium to conventional hydrogen water is similar to that of Earth, they are an even better candidate. Also, asteroids have twenty percent water, but because of their small size, many impacts must have occurred to account for all the water on Earth. Filling the earth with 1,386 million cubic kilometers of water may appear to be a large amount. This quantity of water would have covered the continental United States to a depth of around 145 kilometers (107 miles). However, this is still not much. Water comprises only about 0.02 percent of the mass of our planet.

Furthermore, since Earth has endured heavy bombardment in the past, this scenario is plausible. Researchers also believe that enormous quantities of hydrogen were captured in the planet's rocks and minerals during its formation. Moreover, due to the mantle's heat, minerals rich in hydrogen and oxygen began to dissolve. This allowed water to be expelled from the Earth's crust. Scientists estimate that approximately ten oceans of water exist within the mantle. The volcanic outgassing idea is likely the most remarkable of them. This theory suggests that water may have originated from volcanism. In other words, it has always existed as oxygen- and hydrogen-containing minerals buried beneath the crust of our planet.

Furthermore, volcanoes merely aided in their escape as vapor. It originated from volcanic eruptions before condensing and falling as precipitation. Scientists believe that all volcanic eruptions produce a small amount of water vapor, which may have been sufficient to account for the water on Earth's surface. This remains an unanswered question, but it frequently comes to life with water regardless of the situation.

First life
Most likely, life began during the late Hadean or early Archean Epoch, which spanned from four to two and a half billion years ago. There are signs of life in rocks from Akilia Island, Greenland, that is at least 3.8 billion years old, and the oldest form of life identified by scientists are tiny hematite tubes estimated to be 4.28 billion years old! Hypotheses include a chemical genesis of life in the early atmosphere, hydrothermal vents, deep seas, oceans, and even cosmic comets. The chemical milieu of the early atmosphere and oceans likely gave rise to life. However, they were not comparable to what we have now. There was no oxygen in the atmosphere, but there was an abundance of methane, carbon dioxide, sulfur, and nitrogen compounds.

Moreover, it is known that some solar system space objects possess such an atmosphere. Scientists reproduced our planet's early atmosphere and lightning within an enclosed container in one experiment. After igniting sparks, amino acids, the fundamental building blocks of proteins, were discovered to be produced. Chemosynthesis, and alternative biological process, could have allowed life to exist on the ocean floor without photosynthesis. Instead of utilizing the energy of the Sun, primordial life derived its energy from the heat emanating from the interior of the Earth. There is still the possibility that life originated in space and was brought to Earth by comets or other celestial bodies. Already, amino acids have been identified in meteorites and comets. This concept implies a high probability of life existing elsewhere in the universe.