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Origin Of The Moon
The origin of the Moon is usually explained by a Mars-sized body striking the Earth, making a debris ring that eventually collected into a single natural satellite, the Moon, but there are a number of variations on this giant-impact hypothesis, as well as alternative explanations, and research continues into how the Moon came to be. Other proposed scenarios include captured body, fission, formed together (condensation theory, synestia), planetesimal collisions (formed from asteroid-like bodies), and collision theories. The standard giant-impact hypothesis suggests that a Mars-sized body, called Theia, impacted the proto-Earth, creating a large debris ring around Earth, which then accreted to form the Moon. This collision also resulted in the 23.5° tilted axis of the Earth, thus causing the seasons. The Moon's oxygen isotopic ratios seem to be essentially identical to Earth's. Oxygen isotopic ratios, which may be measured very precisely, yield a unique and distinct signature f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Titanium Isotope
Naturally occurring titanium (22Ti) is composed of five stable isotopes; 46Ti, 47Ti, 48Ti, 49Ti and 50Ti with 48Ti being the most abundant (73.8% natural abundance). Twenty-one radioisotopes have been characterized, with the most stable being 44Ti with a half-life of 60 years, 45Ti with a half-life of 184.8 minutes, 51Ti with a half-life of 5.76 minutes, and 52Ti with a half-life of 1.7 minutes. All of the remaining radioactive isotopes have half-lives that are less than 33 seconds, and the majority of these have half-lives that are less than half a second. The isotopes of titanium range in atomic mass from 38.01 u (38Ti) to 62.99 u (63Ti). The primary decay mode for isotopes lighter than the stable isotopes (lighter than 46Ti) is β+ and the primary mode for the heavier ones (heavier than 50Ti) is β−; their respective decay products are scandium isotopes and the primary products after are vanadium isotopes. List of isotopes , - , rowspan=3, 39Ti , rowspan=3 s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lunar Magma Ocean
The Lunar Magma Ocean (LMO) is the layer of molten rock that is theorized to have been present on the surface of the Moon. The Lunar Magma Ocean was likely present on the Moon from the time of the Moon's formation (about 4.5 or 4.4 billion years ago) to tens or hundreds of millions years after that time. It is a thermodynamic consequence of the Moon's relatively rapid formation in the aftermath of a giant impact between the proto-Earth and another planetary body. As the Moon accreted from the debris from the giant impact, gravitational potential energy was converted to thermal energy. Due to the rapid accretion of the Moon (in about a month to a year), thermal energy was trapped since it did not have sufficient time to thermally radiate away energy through the lunar surface. The subsequent thermochemical evolution of the Lunar Magma Ocean explains the Moon's largely anorthositic crust, europium anomaly, and KREEP material. The Lunar Magma Ocean was initially proposed by two gro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volatiles
Volatiles are the group of chemical elements and chemical compounds that can be readily vaporized. In contrast with volatiles, elements and compounds that are not readily vaporized are known as refractory substances. On planet Earth, the term 'volatiles' often refers to the volatile components of magma. In astrogeology volatiles are investigated in the crust or atmosphere of a planet or moon. Volatiles include nitrogen, carbon dioxide, ammonia, hydrogen, methane, sulfur dioxide, water and others. Planetary science Planetary scientists often classify volatiles with exceptionally low melting points, such as hydrogen and helium, as gases (as in gas giant), whereas those volatiles with melting points above about 100 K (–173 °C, –280 °F) are referred to as ices. The terms "gas" and "ice" in this context can apply to compounds that may be solids, liquids or gases. Thus, Jupiter and Saturn are gas giants, and Uranus and Neptune are ice giants, even though the vast majori ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rocky Planet
A terrestrial planet, telluric planet, or rocky planet, is a planet that is composed primarily of silicate Rock (geology), rocks or metals. Within the Solar System, the terrestrial planets accepted by the IAU are the inner planets closest to the Sun: Mercury (planet), Mercury, Venus, Earth and Mars. Among astronomers who use the geophysical definition of a planet, two or three planetary-mass moon, planetary-mass satellites – Earth's Moon, Io (moon), Io, and sometimes Europa (moon), Europa – may also be considered terrestrial planets; and so may be the rocky protoplanet-asteroids 2 Pallas, Pallas and 4 Vesta, Vesta.Emily Lakdawalla et al.What Is A Planet?The Planetary Society, 21 April 2020 The terms "terrestrial planet" and "telluric planet" are derived from Latin words for Earth (''Terra'' and ''Tellus''), as these planets are, in terms of structure, ''Earth-like''. Terrestrial planets are generally studied by geologists, astronomers, and geophysicists. Terrestrial planets ha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iron
Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in front of oxygen (32.1% and 30.1%, respectively), forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust. In its metallic state, iron is rare in the Earth's crust, limited mainly to deposition by meteorites. Iron ores, by contrast, are among the most abundant in the Earth's crust, although extracting usable metal from them requires kilns or furnaces capable of reaching or higher, about higher than that required to smelt copper. Humans started to master that process in Eurasia during the 2nd millennium BCE and the use of iron tools and weapons began to displace copper alloys, in some regions, only around 1200 BCE. That event is considered the transition from the Bronze Age to the Iron A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Simulation
Computer simulation is the process of mathematical modelling, performed on a computer, which is designed to predict the behaviour of, or the outcome of, a real-world or physical system. The reliability of some mathematical models can be determined by comparing their results to the real-world outcomes they aim to predict. Computer simulations have become a useful tool for the mathematical modeling of many natural systems in physics (computational physics), astrophysics, climatology, chemistry, biology and manufacturing, as well as human systems in economics, psychology, social science, health care and engineering. Simulation of a system is represented as the running of the system's model. It can be used to explore and gain new insights into new technology and to estimate the performance of systems too complex for analytical solutions. Computer simulations are realized by running computer programs that can be either small, running almost instantly on small devices, or large ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Angular Momentum
In physics, angular momentum (rarely, moment of momentum or rotational momentum) is the rotational analog of linear momentum. It is an important physical quantity because it is a conserved quantity—the total angular momentum of a closed system remains constant. Angular momentum has both a direction and a magnitude, and both are conserved. Bicycles and motorcycles, frisbees, rifled bullets, and gyroscopes owe their useful properties to conservation of angular momentum. Conservation of angular momentum is also why hurricanes form spirals and neutron stars have high rotational rates. In general, conservation limits the possible motion of a system, but it does not uniquely determine it. The three-dimensional angular momentum for a point particle is classically represented as a pseudovector , the cross product of the particle's position vector (relative to some origin) and its momentum vector; the latter is in Newtonian mechanics. Unlike linear momentum, angular m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Greek Mythology
A major branch of classical mythology, Greek mythology is the body of myths originally told by the Ancient Greece, ancient Greeks, and a genre of Ancient Greek folklore. These stories concern the Cosmogony, origin and Cosmology#Metaphysical cosmology, nature of the world, the lives and activities of List of Greek mythological figures, deities, Greek hero cult, heroes, and List of Greek mythological creatures, mythological creatures, and the origins and significance of the ancient Greeks' own cult (religious practice), cult and ritual practices. Modern scholars study the myths to shed light on the religious and political institutions of ancient Greece, and to better understand the nature of myth-making itself. The Greek myths were initially propagated in an oral tradition, oral-poetic tradition most likely by Minoan civilization, Minoan and Mycenaean Greece, Mycenaean singers starting in the 18th century BC; eventually the myths of the heroes of the Trojan War and its after ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Goddess
A goddess is a female deity. In many known cultures, goddesses are often linked with literal or metaphorical pregnancy or imagined feminine roles associated with how women and girls are perceived or expected to behave. This includes themes of spinning (textiles), spinning, weaving, beauty, love, sexuality, motherhood, domesticity, creativity, and List of fertility deities, fertility (exemplified by the ancient mother goddess cult). Many major goddesses are also associated with magic (supernatural), magic, war, strategy, hunting, farming, wisdom, fate, earth, sky, power (social and political), power, laws, justice, and more. Some themes, such as Discordianism, discord or disease, which are considered negative within their cultural contexts also are found associated with some goddesses. There are as many differently described and understood goddesses as there are male, shapeshifting, or neuter gods. In some faiths, a sacred female figure holds a central place in religious prayer a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Selene
In ancient Greek mythology and religion, Selene (; grc-gre, Σελήνη , meaning "Moon"''A Greek–English Lexicon's.v. σελήνη) is the goddess and the personification of the Moon. Also known as Mene, she is traditionally the daughter of the Titans Hyperion and Theia, and sister of the sun god Helios and the dawn goddess Eos. She drives her moon chariot across the heavens. Several lovers are attributed to her in various myths, including Zeus, Pan, and the mortal Endymion. In post-classical times, Selene was often identified with Artemis, much as her brother, Helios, was identified with Apollo. Selene and Artemis were also associated with Hecate and all three were regarded as moon and lunar goddesses, but only Selene was regarded as the personification of the Moon itself. Her Roman equivalent is Luna. Names and etymology The name "Selene" is derived from the Greek noun ''selas'' ('), meaning "light, brightness, gleam". In the Doric and Aeolic dialects, her nam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Escape Velocity
In celestial mechanics, escape velocity or escape speed is the minimum speed needed for a free, non- propelled object to escape from the gravitational influence of a primary body, thus reaching an infinite distance from it. It is typically stated as an ideal speed, ignoring atmospheric friction. Although the term "escape velocity" is common, it is more accurately described as a speed than a velocity because it is independent of direction; the escape speed increases with the mass of the primary body and decreases with the distance from the primary body. The escape speed thus depends on how far the object has already traveled, and its calculation at a given distance takes into account that without new acceleration it will slow down as it travels—due to the massive body's gravity—but it will never quite slow to a stop. A rocket, continuously accelerated by its exhaust, can escape without ever reaching escape speed, since it continues to add kinetic energy from its engine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
