Solar System Formation Report PDF

**What is a Hypothesis** A hypothesis is a proposed explanation based on some evidence.  According to the Oxford dictionary, hypothesis is "a supposition or proposed explanation made on the basis of limited evidence as a starting point for further investigation" and Merriam-Webster dictionary defin...

**What is a Hypothesis** A hypothesis is a proposed explanation based on some evidence.  According to the Oxford dictionary, hypothesis is "a supposition or proposed explanation made on the basis of limited evidence as a starting point for further investigation" and Merriam-Webster dictionary defines it as "an idea or theory that is not proven but that leads to further study or discussion." However, a hypothesis is not scientifically tested or proven; it is a logical assumption based on the available evidence. A hypothesis can be accurate or inaccurate. Once the hypothesis is scientifically tested and proven, it becomes a theory.     **What is a Theory** Theory is an idea or set of ideas that is intended to explain facts or events. A theory is formulated after in-depth research analysis. It is always proven scientifically with evidence. The Oxford dictionary defines theory as "supposition or a system of ideas intended to explain something, especially one based on general principles independent of the thing to be explained." As mentioned above, a theory is usually formulated from a hypothesis. Once a hypothesis is tested and proven, it is accepted as a theory. Copernicus' Heliocentric theory, Darwin's theory of evolution, quantum theory, special relativity theory, are examples of are some important scientific theories. A theory can be used to understand, explain and make predictions over a concept. However, theories can be proven to be wrong as well, depending on the proof. However, theoretical knowledge is important in understanding different concepts and situations. **Solar Nebular Theory/ Core Accretion Model** **[The Solar Nebular Theory/ Core Accretion Model]** *Source: Holt, M., Rinehart, & Winston. (2007). Earth science, Interactive textbook: Holt science & technology. Place of publication not identified, Texas: Holt Mcdougal.* You probably know that our solar system today includes the planets, moons, and other objects that orbit our sun. However, our solar system has existed for only about 5 billion years. It was not always the same as it is now. It began as a nebula All solar systems start as clouds of gas and dust in space called **nebulas **(or *nebulae*). Our solar system probably formed from a nebula called the **solar nebula**. The gases in a nebula are mainly hydrogen and helium. The dust contains elements such as carbon and iron. Solar systems form from nebulas. The gas and dust in nebulas become solar systems because of two forces: gravity and pressure.   **[GRAVITY: PULLING MATTER TOGETHER]** Remember that gravity pulls objects together. The particles of matter in a nebula are very small. There is a lot of space between them. Therefore, the force of gravity holding the particles together is very weak. It is just strong enough to keep the nebula from drifting apart.   **[PRESSURE: PUSHING MATTER APART]** Gravity pulls the particles in a nebula together. Why don't the particles collapse into a single point? The answer has to do with the pressure inside a nebula. The particles in a nebula are always moving. As the particles move around, they sometimes bump into each other. When two particles bump into each other, they move apart. This produces ***pressure*** within the nebula. The closer the particles are, the more likely they are to bump into each other. Therefore, the pressure is high.   **[THE BALANCE BETWEEN GRAVITY AND PRESSURE]** High pressure causes the nebula to *expand*, or get larger. The particles spread farther apart, and pressure decreases. However, gravity increases pressure by pulling the particles together. When the nebula is just the right size, the pressure inside it exactly balances the force of gravity. This balance keeps the nebula the same size. It does not expand or shrink.   **[UPSETTING THE BALANCE]** The balance between gravity and pressure in a nebula can be *upset*, or changed. For example, a supernova\ can produce a force on the nebula. The force can cause small regions of the nebula to be *compressed, *or pushed together. These small regions are called *globules*. A globule can become very dense. Gravity can cause the globule to collapse. As it collapses, its temperature increases. The hot, dense globule can eventually become a star.   **[How Did the Solar System Form?]** It took about ten million years for our solar system to form from the solar nebula. The figures below show some of the important events in the formation of our solar system. **The Atmosphere** - The atmosphere is the thin gaseous layer that envelopes the lithosphere. - The present atmosphere is composed of 78% nitrogen (N), 21% oxygen (O2), 0.9% argon, and trace amount of other gases. - One of the most important processes by which the heat on the Earth\'s surface is redistributed is through atmospheric circulation. - There is also a constant exchange of heat and moisture between the atmosphere and the hydrosphere through the hydrologic cycle.   **The Lithosphere** - The lithosphere includes the rocks of the crust and mantle, the metallic liquid outer core, and the solid metallic inner core. - Lithosphere is like the skeleton of the planet. All the other systems lie on top of it. - Lithosphere comprises the **Solid Earth (non-living)**.   **The Biosphere** - The biosphere is the set of all life forms on Earth. - It covers all ecosystems---from the soil to the rainforest, from mangroves to coral reefs, and from the plankton-rich ocean surface to the deep sea. - For the majority of life on Earth, the base of the food chain comprises photosynthetic organisms. During **photosynthesis**, CO2 is sequestered from the atmosphere, while oxygen is released as a byproduct. - The biosphere is a CO2 sink, and therefore, an important part of the **carbon cycle**.   **The Hydrosphere** - About 70% of the Earth is covered with liquid water (hydrosphere) and much of it is in the form of ocean water. - Only 3% of Earth\'s water is fresh: two-thirds are in the form of ice, and the remaining one-third is present in streams, lakes, and groundwater. **What defines a Rock?** - - Rocks are formed from an aggregation of one or more minerals and other substances that are cohered into a solid structure. - Rocks contain clues, valuable information about the environment in which they were formed.  - To geologists, a rock is a natural substance composed of solid crystals of different minerals that have been fused together into a solid lump. The minerals may or may not have been formed at the same time. What matters is that natural processes glued them all together.  **What branch of geology deals with the study of rocks?** **                   Petrology ***[is a branch of geology that focuses on the origin, composition, structure, and classification of rocks]*. It involves examining the physical and chemical properties of rocks to understand their formation processes and geological history. There are different subfields within petrology that focus on specific types of rocks, such as **[igneous petrology]**, **[sedimentary petrology]**, and **[metamorphic petrology]**. **Petrologist** a geologist who unravel and interpret that information. - - - - **Igneous petrology** [involves the study of the origin and nature of magma.] Igneous petrology [also involves the identification, classification, origin, evolution, and processes of formation and crystallization of igneous rocks.] - **Sedimentary petrology **[studies the mineralogical and geochemical composition of sediments and sedimentary rocks to determine depositional and post-depositional processes of formation.] - **Metamorphic petrology **is the [study of all rocks that are formed by crystallization in the solid state, beyond the field of diagenesis.] The three main types of rocks are **igneous**, **sedimentary**, and **metamorphic** rocks. Each type forms through different processes and has distinct characteristics: **1. Igneous Rocks** - **Formation**: Igneous rocks form from the cooling and solidification of molten rock, either magma (below the Earth\'s surface) or lava (on the surface). - **Examples**: Granite (intrusive), Basalt (extrusive). - **Characteristics**: - Intrusive igneous rocks cool slowly beneath the Earth\'s surface, allowing large crystals to form (e.g., granite). - Extrusive igneous rocks cool quickly on the surface, resulting in small crystals or a glassy texture (e.g., basalt, obsidian). **2. Sedimentary Rocks** - **Formation**: Sedimentary rocks form from the accumulation and compaction of sediments, which are small particles of other rocks, minerals, or organic materials. These sediments often accumulate in layers over time, typically in water bodies. - **Examples**: Limestone, Sandstone, Shale. - **Characteristics**: - Sedimentary rocks often have distinct layers, or strata, and may contain fossils. - They can form through mechanical (clastic), chemical, or organic processes, depending on how the sediments were created and deposited. **3. Metamorphic Rocks** - **Formation**: Metamorphic rocks form when existing rocks (either igneous, sedimentary, or even other metamorphic rocks) are subjected to high heat, pressure, or chemically active fluids, causing them to change in structure or mineral composition. - **Examples**: Marble (from limestone), Slate (from shale). - **Characteristics**: - Metamorphic rocks often exhibit foliation (layering) or a crystalline texture due to the recrystallization of minerals under pressure. - They are more dense and harder than their original forms due to the intense conditions they have undergone.