Hadean Eon - Revision history

Jojo: /* Emergence of Organic Molecules */

2024-03-23T15:55:33Z

Emergence of Organic Molecules

@@ Line 264: / Line 264: @@
 Organic molecules are the chemical foundation for life as we know it. '''Amino acids''' form '''proteins''', '''nucleotides''' form '''RNA''' and '''DNA''', and '''fatty acids''' contribute to '''cell membranes'''. The presence and availability of these organic molecules set the stage for the emergence of life, providing the necessary components for the development of self-replicating systems.
 [[Category:Physics]]
 [[Category:Astronomy]]

Jojo: /* Kuiper Belt and Oort Cloud Formation */

2024-03-23T15:31:10Z

Kuiper Belt and Oort Cloud Formation

← Older revision		Revision as of 11:31, 23 March 2024
Line 150:		Line 150:
	The outcome of this conservation is that as the molecular cloud that became the solar system collapsed, it spun faster, leading to the formation of a rotating protostar - the young Sun. Over time, the Sun reached its current rotation period, which is about 25 days at the equator and longer at higher latitudes, due to its gaseous nature allowing for differential rotation. Over time, the distribution of the Sun's mass and interactions between its magnetic field and the solar wind (a stream of charged particles emitted by the Sun) have likely influenced its rotation rate, a process known as magnetic braking. This process can gradually slow down the rotation rate of stars, including the Sun.		The outcome of this conservation is that as the molecular cloud that became the solar system collapsed, it spun faster, leading to the formation of a rotating protostar - the young Sun. Over time, the Sun reached its current rotation period, which is about 25 days at the equator and longer at higher latitudes, due to its gaseous nature allowing for differential rotation. Over time, the distribution of the Sun's mass and interactions between its magnetic field and the solar wind (a stream of charged particles emitted by the Sun) have likely influenced its rotation rate, a process known as magnetic braking. This process can gradually slow down the rotation rate of stars, including the Sun.

	== ~~Planetary~~ Accretion ==		== Solar System Bodily Accretion ==
	Even as the densest regions of the molecular cloud collapsed and began protostars, other bodies had begun to form in the cooler, less dense regions of the '''accretion disk''' surrounding this more active center. The process of planetary accretion begins with the coalescence of dust and ice particles into larger bodies through '''electrostatic forces''' and '''gravity'''. Over time, these bodies grow into planetesimals and eventually protoplanets, influenced by the composition of the accretion disk, which varies with distance from the protostar, and the dynamic interactions within the disk itself.		Even as the densest regions of the molecular cloud collapsed and began protostars, other bodies had begun to form in the cooler, less dense regions of the '''accretion disk''' surrounding this more active center. The process of planetary accretion begins with the coalescence of dust and ice particles into larger bodies through '''electrostatic forces''' and '''gravity'''. Over time, these bodies grow into planetesimals and eventually protoplanets, influenced by the composition of the accretion disk, which varies with distance from the protostar, and the dynamic interactions within the disk itself.

Line 250:		Line 250:
	The <u>Oort Cloud</u> is a distant, spherical shell of icy objects surrounding the Solar System, believed to extend up to 100,000 AU from the Sun. It is thought to have formed from the scattering of icy bodies by the gas giants' gravitational forces into distant orbits. Some of these objects were likely ejected to the cloud's outer reaches, while others were pulled into the inner Solar System as comets.		The <u>Oort Cloud</u> is a distant, spherical shell of icy objects surrounding the Solar System, believed to extend up to 100,000 AU from the Sun. It is thought to have formed from the scattering of icy bodies by the gas giants' gravitational forces into distant orbits. Some of these objects were likely ejected to the cloud's outer reaches, while others were pulled into the inner Solar System as comets.

			== Emergence of Organic Molecules ==
			Organic molecules are defined by their carbon-based structure; '''carbon'''<nowiki/>'s unique ability to form <u>four stable bonds</u> with other atoms, including other carbon atoms, allows for the creation of a vast diversity of complex molecular structures. This property is the cornerstone of organic chemistry and is central to the formation of the molecules that constitute living organisms.

			At the simplest level, organic molecules include '''hydrocarbons''', which are compounds made solely of carbon and hydrogen. However, the category encompasses a much broader array of molecules that contain carbon-hydrogen bonds along with other elements, notably oxygen, nitrogen, phosphorus, and sulfur. These elements are key components of life's critical molecules, such as '''nucleic acids''' (DNA and RNA), '''proteins''', '''carbohydrates''', and '''lipids'''. Organic molecules are often associated with complexity and the potential for participating in biochemical processes, as they can serve as building blocks for life, and are involved in key functions such as energy storage, structural integrity, information transfer, and catalysis of biochemical reactions.

			Inorganic molecules are <u>not</u> based on carbon-hydrogen bonds; while they can contain carbon (such as carbon dioxide, CO2), they do not exhibit the complex carbon-based structures characteristic of organic molecules. Inorganic chemistry covers a broad range of substances, including metals, salts, and minerals. In general, inorganic molecules have simpler structures; they play crucial roles in various physical and chemical processes, including those relevant to geological and atmospheric phenomena, as well as in biological systems (metal ions in enzymes and electrolytes in bodily fluids, et cetera). Despite their simplicity, inorganic molecules are essential for life and the environment. They participate in Earth's geochemical cycles, act as catalysts in industrial processes, and form the basis of many pigments and structural materials.

			The distinction between organic and inorganic molecules is not always clear-cut; some compounds, like '''carbonates''' (calcium carbonate) and simple '''carbon oxides''' (carbon monoxide, CO, and carbon dioxide, CO2), are traditionally classified as inorganic despite containing carbon. The key differentiation often lies in the complexity of the molecule and its potential or actual role in biological systems. Organic molecules, including simple hydrocarbons, '''alcohols''', and more complex compounds like '''amino acids''', have their origins in the interstellar medium (ISM). The cold, dense clouds within the ISM are sites of complex chemistry, where ultraviolet radiation, cosmic rays, and the presence of dust grains catalyze the formation of these molecules from simpler components like molecular hydrogen (H2), carbon monoxide (CO), and ammonia (NH3).

			As the Solar System formed from a collapsing molecular cloud, these organic molecules were incorporated into the protoplanetary disk surrounding the young Sun; the varying temperatures and pressures within the disk influenced the complexity and distribution of organic compounds, with ices and volatile compounds condensing in the cooler outer regions.

			These early organic compounds were likely delivered to the terrestrial planets, including Earth, via comets and asteroids; the '''carbonaceous chondrites''', a type of stony meteorite rich in organic compounds, are thought to be remnants of the early Solar System's building blocks. Their impact on the young Earth could have seeded the planet with the organic precursors necessary for life. Additionally, the synthesis of organic molecules could also occur on the early Earth's surface and its oceans, driven by energy sources like UV radiation, lightning, and '''hydrothermal vents'''. The <u>Miller-Urey experiment</u> famously demonstrated that amino acids could be synthesized from simple gases and an energy source, mimicking the conditions of early Earth.

			Organic molecules are the chemical foundation for life as we know it. '''Amino acids''' form '''proteins''', '''nucleotides''' form '''RNA''' and '''DNA''', and '''fatty acids''' contribute to '''cell membranes'''. The presence and availability of these organic molecules set the stage for the emergence of life, providing the necessary components for the development of self-replicating systems.
	[[Category:Physics]]		[[Category:Physics]]
	[[Category:Astronomy]]		[[Category:Astronomy]]

Jojo: /* The Asteroid Belt */

2024-03-23T15:19:33Z

The Asteroid Belt

← Older revision		Revision as of 11:19, 23 March 2024
Line 237:		Line 237:

	The asteroid belt contains bodies ranging in size from <u>Ceres</u>, the largest asteroid and a dwarf planet with a diameter of about 940 kilometers, down to dust particles. The size distribution of asteroids follows a '''power-law distribution''', meaning there are many more small asteroids than large ones. This distribution is indicative of a '''collisional evolution''' where larger bodies are broken into smaller pieces over time. Besides Ceres, other large asteroids include <u>Vesta</u>, <u>Pallas</u>, and <u>Hygiea</u>, which have diameters of approximately 525 km, 512 km, and 430 km, respectively. These large asteroids constitute a significant portion of the belt's total mass.		The asteroid belt contains bodies ranging in size from <u>Ceres</u>, the largest asteroid and a dwarf planet with a diameter of about 940 kilometers, down to dust particles. The size distribution of asteroids follows a '''power-law distribution''', meaning there are many more small asteroids than large ones. This distribution is indicative of a '''collisional evolution''' where larger bodies are broken into smaller pieces over time. Besides Ceres, other large asteroids include <u>Vesta</u>, <u>Pallas</u>, and <u>Hygiea</u>, which have diameters of approximately 525 km, 512 km, and 430 km, respectively. These large asteroids constitute a significant portion of the belt's total mass.

			Some asteroids are grouped into families or clusters based on similarities in their orbital parameters. These families are thought to be the remnants of larger parent bodies that were shattered by collisions. Moreover, gravitational resonances with Jupiter and other planets have sculpted the distribution and dynamics of asteroids within the belt.

	=== The Giants ===		=== The Giants ===

Jojo: /* The Asteroid Belt */

2024-03-23T15:13:53Z

The Asteroid Belt

← Older revision		Revision as of 11:13, 23 March 2024
Line 235:		Line 235:

	The asteroid belt contains a diverse range of bodies, from rocky to icy, reflecting the compositional gradient of the solar nebula. The early Hadean would have seen significant collisional evolution in the belt, with impacts leading to fragmentation, accretion, and the ejection of material. Some of this ejected material would have contributed to the late heavy bombardment of the inner Solar System.		The asteroid belt contains a diverse range of bodies, from rocky to icy, reflecting the compositional gradient of the solar nebula. The early Hadean would have seen significant collisional evolution in the belt, with impacts leading to fragmentation, accretion, and the ejection of material. Some of this ejected material would have contributed to the late heavy bombardment of the inner Solar System.

			The asteroid belt contains bodies ranging in size from <u>Ceres</u>, the largest asteroid and a dwarf planet with a diameter of about 940 kilometers, down to dust particles. The size distribution of asteroids follows a '''power-law distribution''', meaning there are many more small asteroids than large ones. This distribution is indicative of a '''collisional evolution''' where larger bodies are broken into smaller pieces over time. Besides Ceres, other large asteroids include <u>Vesta</u>, <u>Pallas</u>, and <u>Hygiea</u>, which have diameters of approximately 525 km, 512 km, and 430 km, respectively. These large asteroids constitute a significant portion of the belt's total mass.

	=== The Giants ===		=== The Giants ===

Jojo: /* The Giants */

2024-03-23T15:06:49Z

The Giants

← Older revision		Revision as of 11:06, 23 March 2024
Line 240:		Line 240:

	Uranus and Neptune are often referred to as '''ice giants''' due to their large compositions of volatiles (substances that easily become gas) like water, methane, and ammonia, in addition to hydrogen and helium. These planets formed further from the Sun, where temperatures were low enough for these compounds to condense.		Uranus and Neptune are often referred to as '''ice giants''' due to their large compositions of volatiles (substances that easily become gas) like water, methane, and ammonia, in addition to hydrogen and helium. These planets formed further from the Sun, where temperatures were low enough for these compounds to condense.

	The current positions and compositions of Uranus and Neptune suggest that they may have formed closer to the Sun than their present-day orbits or experienced significant migration due to gravitational interactions, possibly with each other or with the gas giants.

	=== Kuiper Belt and Oort Cloud Formation ===		=== Kuiper Belt and Oort Cloud Formation ===

Jojo: /* The Giants */

2024-03-23T15:06:36Z

The Giants

← Older revision		Revision as of 11:06, 23 March 2024
Line 226:		Line 226:

	Mars' atmosphere is thin and composed mostly of carbon dioxide, with trace amounts of nitrogen, argon, and oxygen.		Mars' atmosphere is thin and composed mostly of carbon dioxide, with trace amounts of nitrogen, argon, and oxygen.

			=== The Asteroid Belt ===
			<u>Jupiter</u> formed from the solar nebula relatively quickly in Solar System history, accumulating a massive atmosphere of hydrogen and helium around a rocky and icy core. Its rapid growth allowed it to dominate the gravitational dynamics of the young Solar System. Models of Solar System evolution, such as the '''Grand Tack hypothesis''', suggest that Jupiter initially migrated inward towards the Sun, due to interactions with the gas and dust in the protoplanetary disk. This inward migration could have had dramatic effects on the inner Solar System, including the distribution and composition of material in the terrestrial planet region.

			According to the Grand Tack hypothesis, as Saturn formed and migrated inward, its interaction with Jupiter resulted in a gravitational tug that reversed Jupiter's direction, causing both planets to migrate outward to their current positions. This "tack" could explain the small size of Mars as well as the composition of the asteroid belt. Jupiter's outward migration, along with Saturn, would have influenced the formation and migration of the ice giants, Uranus and Neptune, potentially pushing them to their current locations and into the Kuiper belt, scattering objects in the process.

			Jupiter’s massive gravity disturbed the orbital paths of nearby planetesimals and protoplanets, preventing them from coalescing into a larger planet in the region of the asteroid belt. Its location is significantly influenced by '''gravitational resonances''' with Jupiter, which occur when the orbital period of a body in the belt is a simple fraction (like 2:1 or 3:2) of Jupiter’s orbital period, leading to gravitational interactions that can alter the body's orbit. This has led to gaps in the asteroid belt, known as '''Kirkwood gaps''', and helped prevent the formation of a planet in this region.

			The asteroid belt contains a diverse range of bodies, from rocky to icy, reflecting the compositional gradient of the solar nebula. The early Hadean would have seen significant collisional evolution in the belt, with impacts leading to fragmentation, accretion, and the ejection of material. Some of this ejected material would have contributed to the late heavy bombardment of the inner Solar System.

	=== The Giants ===		=== The Giants ===
	Jupiter and Saturn likely formed from the accretion of hydrogen and helium gas ~~surrounding a core of rock and ice~~. Jupiter, being the ~~largest planet~~, ~~probably~~ formed first, ~~influencing~~ the ~~formation~~ and ~~migration~~ of ~~other~~ planets, ~~including Saturn~~.		<u>Jupiter</u> and <u>Saturn</u>, the '''gas giants''', likely formed from the accretion of icy and rocky material into large cores, followed by the rapid accumulation of hydrogen and helium gas from the solar nebula. Jupiter, being closer to the Sun and forming in a region of the nebula with a higher density of materials, likely formed first, with Saturn following. This model suggests that once these planets' cores reached a critical mass, they were able to gravitationally attract and retain the surrounding gas, growing rapidly into the gas giants we recognize today.

			Uranus and Neptune are often referred to as '''ice giants''' due to their large compositions of volatiles (substances that easily become gas) like water, methane, and ammonia, in addition to hydrogen and helium. These planets formed further from the Sun, where temperatures were low enough for these compounds to condense.

			The current positions and compositions of Uranus and Neptune suggest that they may have formed closer to the Sun than their present-day orbits or experienced significant migration due to gravitational interactions, possibly with each other or with the gas giants.

	~~Often referred to as ice giants~~, ~~Uranus and~~ Neptune's ~~formation involved~~ the ~~accretion~~ of icy ~~material in addition to rock~~. ~~Their~~ formation ~~and current positions in~~ the ~~Solar System are thought to be~~ the ~~result~~ of ~~interactions with Jupiter and Saturn~~, ~~causing them to migrate outward~~.		=== Kuiper Belt and Oort Cloud Formation ===
			The <u>Kuiper Belt</u>, extending from beyond Neptune's orbit out to approximately 55 astronomical units (AU) from the Sun, began to take shape in the Hadean era. It is composed of icy bodies, including dwarf planets like <u>Pluto</u>. The formation of the Kuiper Belt was likely influenced by the gravitational perturbations of the giants, particularly <u>Neptune</u>.

	~~=== Asteroid Belt ===~~		The <u>Oort Cloud</u> is a distant, spherical shell of icy objects surrounding the Solar System, believed to extend up to 100,000 AU from the Sun. It is thought to have formed from the scattering of icy bodies by the gas giants' gravitational forces into distant orbits. Some of these objects were likely ejected to the cloud's outer reaches, while others were pulled into the inner Solar System as comets.
	The ~~formation~~ of the ~~asteroid belt~~, ~~located between Mars and Jupiter~~, is ~~attributed~~ to the gravitational ~~influence~~ of ~~Jupiter~~, ~~which prevented~~ the ~~accretion of materials in this region into a larger planet~~.

	~~=== Kuiper Belt ===~~
	Beyond Neptune lies the Kuiper Belt, a region filled with icy bodies. The comets we occasionally see in the inner Solar System are believed to originate from either the Kuiper Belt or the more distant Oort Cloud.
	[[Category:Physics]]		[[Category:Physics]]
	[[Category:Astronomy]]		[[Category:Astronomy]]

Jojo: /* The Giants */

2024-03-23T14:46:03Z

The Giants

← Older revision		Revision as of 10:46, 23 March 2024
Line 217:		Line 217:

	Aside from its fiery beginnings which likely would have vaporized or expelled most volatile elements, it also has a light gravity, making the retention of necessary elements to build an atmosphere difficult. Adding to the difficulty is a lack of magnetic field, such that the solar wind would strip the Moon of any gaseous accumulation even if it had a chance to gather there.		Aside from its fiery beginnings which likely would have vaporized or expelled most volatile elements, it also has a light gravity, making the retention of necessary elements to build an atmosphere difficult. Adding to the difficulty is a lack of magnetic field, such that the solar wind would strip the Moon of any gaseous accumulation even if it had a chance to gather there.

			==== Mars ====
			Young Mars quickly underwent differentiation, where its denser materials, such as iron, sank to form a metallic core, while lighter silicates floated to form its mantle and crust. This process was likely aided by the heat generated from accretion, radioactive decay, and potential early tidal heating effects if Mars had a more substantial moon or moons in its past. Volcanic activity on early Mars released gases trapped in the mantle, contributing to the formation of its primary atmosphere, which likely included water vapor, carbon dioxide, and nitrogen. Impacts from comets and asteroids are believed to have delivered additional volatiles, including water, to Mars. These events could have been particularly significant during the Late Heavy Bombardment period, enriching Mars with the necessary ingredients for a thicker atmosphere and liquid water on its surface.

			Evidence from valley networks and mineralogical features suggests that Mars experienced periods of warmer and wetter conditions, particularly in its early history. These conditions might have allowed for the temporary presence of liquid '''water''' on its surface, shaping the planet's landscape through erosion and sediment deposition. Over time, Mars lost much of its atmosphere to space, a process accelerated by the solar wind and the lack of a global magnetic field to protect it. As the atmosphere thinned, Mars's ability to retain heat diminished, leading to the cold, arid conditions observed today.

			Mars hosts some of the largest volcanoes in the Solar System, such as <u>Olympus Mons</u>; these volcanoes are a testament to the planet's volcanic activity, which has played a crucial role in shaping its surface and atmosphere. Unlike Earth, Mars does not show evidence of active plate tectonics. However, features such as the <u>Valles Marineris</u>, a vast canyon system, suggest that the planet has experienced significant '''crustal deformation''', possibly related to volcanic upwelling and the contraction of the planet's crust as it cooled. Mars has polar '''ice caps''' composed of water ice and frozen carbon dioxide. These caps contain valuable records of Mars' climate history and undergo seasonal changes that affect the planet's climate and atmospheric pressure.

			Mars' atmosphere is thin and composed mostly of carbon dioxide, with trace amounts of nitrogen, argon, and oxygen.

	=== The Giants ===		=== The Giants ===

Jojo: /* Formation of the Moon */

2024-03-23T14:39:43Z

Formation of the Moon

← Older revision		Revision as of 10:39, 23 March 2024
Line 216:		Line 216:
	The Moon does not have active plate tectonics; lunar geology is characterized by the vast lunar '''maria''' (formed by ancient volcanic flows), highlands, and impact craters. Its surface is covered by '''regolith''', a layer of fragmented material produced by the impact of '''micrometeorites''' and its thermal expansion and contraction during the lunar day-night cycle. This feature, while not unique to the Moon among terrestrial bodies, is more pronounced due to the Moon's lack of atmosphere and water.		The Moon does not have active plate tectonics; lunar geology is characterized by the vast lunar '''maria''' (formed by ancient volcanic flows), highlands, and impact craters. Its surface is covered by '''regolith''', a layer of fragmented material produced by the impact of '''micrometeorites''' and its thermal expansion and contraction during the lunar day-night cycle. This feature, while not unique to the Moon among terrestrial bodies, is more pronounced due to the Moon's lack of atmosphere and water.

	Aside from its fiery beginnings which likely would have vaporized or expelled most volatile elements, it also has a light gravity, making the retention of ~~such materials~~ to build an atmosphere difficult. Adding to the difficulty is a lack of magnetic field, such that the solar wind would strip the Moon of any gaseous accumulation ~~as well~~.		Aside from its fiery beginnings which likely would have vaporized or expelled most volatile elements, it also has a light gravity, making the retention of necessary elements to build an atmosphere difficult. Adding to the difficulty is a lack of magnetic field, such that the solar wind would strip the Moon of any gaseous accumulation even if it had a chance to gather there.

	=== The Giants ===		=== The Giants ===

Jojo: /* Formation of the Moon */

2024-03-23T14:38:14Z

Formation of the Moon

← Older revision		Revision as of 10:38, 23 March 2024
Line 214:		Line 214:
	The Moon shows a marked depletion in '''volatile elements''' compared to Earth and the other terrestrial planets, thought to be the result of the high-temperature environment of the Moon's formation, where much of the volatile material was lost to space. Early assumptions posited the Moon was entirely dry, but recent missions and studies have found trace amounts of water within lunar rocks and potentially significant ice deposits in permanently shadowed craters at the poles. These water levels are still far lower than on Earth.		The Moon shows a marked depletion in '''volatile elements''' compared to Earth and the other terrestrial planets, thought to be the result of the high-temperature environment of the Moon's formation, where much of the volatile material was lost to space. Early assumptions posited the Moon was entirely dry, but recent missions and studies have found trace amounts of water within lunar rocks and potentially significant ice deposits in permanently shadowed craters at the poles. These water levels are still far lower than on Earth.

	~~=== Isotopic Composition ===~~		The Moon does not have active plate tectonics; lunar geology is characterized by the vast lunar '''maria''' (formed by ancient volcanic flows), highlands, and impact craters. Its surface is covered by '''regolith''', a layer of fragmented material produced by the impact of '''micrometeorites''' and its thermal expansion and contraction during the lunar day-night cycle. This feature, while not unique to the Moon among terrestrial bodies, is more pronounced due to the Moon's lack of atmosphere and water.

	* Similarity to Earth: The isotopic composition of the Moon, ~~especially oxygen isotopes~~, ~~is remarkably similar to that of Earth's mantle. This similarity supports~~ the ~~Giant Impact Hypothesis, suggesting a common origin for much~~ of ~~the material that makes up the Earth and Moon.~~		Aside from its fiery beginnings which likely would have vaporized or expelled most volatile elements, it also has a light gravity, making the retention of such materials to build an atmosphere difficult. Adding to the difficulty is a lack of magnetic field, such that the solar wind would strip the Moon of any gaseous accumulation as well.
	* Difference from Other Terrestrial Planets: The isotopic signatures of lunar rocks show differences from meteorites believed to ~~originate from Mars and other bodies in the asteroid belt, underscoring the unique relationship between Earth and the Moon~~.

	~~=== Surface Geology ===~~

	* Lack of Plate Tectonics: The Moon does not have active plate tectonics, which shapes the geology of Earth and, to ~~a lesser extent, influences the other terrestrial planets. Lunar geology is characterized by~~ the ~~vast lunar maria (formed by ancient volcanic flows), highlands, and impact craters.~~
	* Regolith: The Moon's surface is ~~covered by regolith,~~ a ~~layer of fragmented material produced by the impact~~ of ~~micrometeorites and the thermal expansion and contraction during the lunar day-night cycle. This feature~~, ~~while not unique to~~ the ~~Moon among terrestrial bodies, is more pronounced due to~~ the Moon~~'s lack~~ of ~~atmosphere and water~~.

	=== The Giants ===		=== The Giants ===

Jojo: /* Formation of the Moon */

2024-03-23T14:33:39Z

Formation of the Moon

← Older revision		Revision as of 10:33, 23 March 2024
Line 209:		Line 209:

	The impact could have stripped away part of Earth's existing atmosphere, leading to the formation of a new secondary atmosphere. The energy delivered by the impact and the subsequent increase in volcanic activity would have contributed to the outgassing of water vapor and other gases, influencing the development of the planet's '''hydrosphere'''. The exchange of material between Earth and Theia during the collision contributed to the chemical similarities between Earth's mantle and the Moon. This exchange is a key piece of evidence supporting the Giant Impact Hypothesis, as it explains why Moon rocks have '''isotopic compositions''' similar to Earth's mantle rather than being entirely distinct.		The impact could have stripped away part of Earth's existing atmosphere, leading to the formation of a new secondary atmosphere. The energy delivered by the impact and the subsequent increase in volcanic activity would have contributed to the outgassing of water vapor and other gases, influencing the development of the planet's '''hydrosphere'''. The exchange of material between Earth and Theia during the collision contributed to the chemical similarities between Earth's mantle and the Moon. This exchange is a key piece of evidence supporting the Giant Impact Hypothesis, as it explains why Moon rocks have '''isotopic compositions''' similar to Earth's mantle rather than being entirely distinct.

			The bulk of the Moon is made up of silicate materials, similar to the terrestrial planets; this includes a '''mantle''' composed primarily of olivine, pyroxene, and lesser amounts of minerals like spinel, and a '''crust''' that is rich in anorthosite, a type of rock composed mostly of plagioclase feldspar. Unlike the terrestrial planets, which have substantial iron cores, the Moon has a relatively small core, thought to comprise a small fraction of its mass (1-2%).

			The Moon shows a marked depletion in '''volatile elements''' compared to Earth and the other terrestrial planets, thought to be the result of the high-temperature environment of the Moon's formation, where much of the volatile material was lost to space. Early assumptions posited the Moon was entirely dry, but recent missions and studies have found trace amounts of water within lunar rocks and potentially significant ice deposits in permanently shadowed craters at the poles. These water levels are still far lower than on Earth.

			=== Isotopic Composition ===

			* Similarity to Earth: The isotopic composition of the Moon, especially oxygen isotopes, is remarkably similar to that of Earth's mantle. This similarity supports the Giant Impact Hypothesis, suggesting a common origin for much of the material that makes up the Earth and Moon.
			* Difference from Other Terrestrial Planets: The isotopic signatures of lunar rocks show differences from meteorites believed to originate from Mars and other bodies in the asteroid belt, underscoring the unique relationship between Earth and the Moon.

			=== Surface Geology ===

			* Lack of Plate Tectonics: The Moon does not have active plate tectonics, which shapes the geology of Earth and, to a lesser extent, influences the other terrestrial planets. Lunar geology is characterized by the vast lunar maria (formed by ancient volcanic flows), highlands, and impact craters.
			* Regolith: The Moon's surface is covered by regolith, a layer of fragmented material produced by the impact of micrometeorites and the thermal expansion and contraction during the lunar day-night cycle. This feature, while not unique to the Moon among terrestrial bodies, is more pronounced due to the Moon's lack of atmosphere and water.

	=== The Giants ===		=== The Giants ===