themoo37

After fusing helium in its core to carbon, the Sun will begin to collapse again, evolving into a compact white dwarf star after ejecting its outer atmosphere as a planetary nebula. In 50 billion years, if the Earth and Moon are not engulfed by the Sun, they will become tidelocked, with each showing only one face to the other. Thereafter, the tidal action of the Sun will extract angular momentum from the system, causing the lunar orbit to decay and the Earth's spin to accelerate. Over time intervals of around 30 trillion years, the Sun will undergo a close encounter with another star. As a consequence, the orbits of their planets can become disrupted, potentially ejecting them from the system entirely. If Earth is not destroyed by the expanding red giant Sun in 7.6 billion years and not ejected from its orbit by a stellar encounter, its ultimate fate will be that it collides with the black dwarf Sun due to the decay of its orbit via gravitational radiation, in 100 quintillion years....

Once the Sun changes from burning hydrogen at its core to burning hydrogen around its shell, the core will start to contract and the outer envelope will expand. The total luminosity will steadily increase over the following billion years until it reaches 2,730 times the Sun's current luminosity at the age of 12.167 billion years. Most of Earth's atmosphere will be lost to space and its surface will consist of a lava ocean with floating continents of metals and metal oxides as well as icebergs of refractory materials, with its surface temperature reaching more than 2,400 K (2,130 °C; 3,860 °F). The Sun will experience more rapid mass loss, with about 33% of its total mass shed with the solar wind. The loss of mass will mean that the orbits of the planets will expand. The orbital distance of the Earth will increase to at most 150% of its current value. The most rapid part of the Sun's expansion into a red giant will occur during the final stages, when the Sun will be about 12...

One billion years from now, about 27% of the modern ocean will have been subducted into the mantle. If this process were allowed to continue uninterrupted, it would reach an equilibrium state where 65% of the current surface reservoir would remain at the surface. Once the solar luminosity is 10% higher than its current value, the average global surface temperature will rise to 320 K (47 °C; 116 °F). The atmosphere will become a "moist greenhouse" leading to a runaway evaporation of the oceans. At this point, models of the Earth's future environment demonstrate that the stratosphere would contain increasing levels of water. These water molecules will be broken down through photodissociation by solar ultraviolet radiation, allowing hydrogen to escape the atmosphere. The net result would be a loss of the world's sea water by about 1.1 billion years from the present. This will be a simple dramatic step in annihilating all life on Earth. There will be two variations of thi...

The biological and geological future of Earth can be extrapolated based upon the estimated effects of several long-term influences. These include the chemistry at Earth's surface, the rate of cooling of the planet's interior, the gravitational interactions with other objects in the Solar System, and a steady increase in the Sun's luminosity. An uncertain factor in this extrapolation is the ongoing influence of technology introduced by humans, such as climate engineering, which could cause significant changes to the planet. The current Holocene extinction is being caused by technology and the effects may last for up to five million years. In turn, technology may result in the extinction of humanity, leaving the planet to gradually return to a slower evolutionary pace resulting solely from long-term natural processes. Over time intervals of hundreds of millions of years, random celestial events pose a global risk to the biosphere, which can result in mass extinctions. These i...

Oxygen accumulation from photosynthesis resulted in the formation of an ozone layer that absorbed much of the Sun's ultraviolet radiation, meaning unicellular organisms that reached land were less likely to die, and prokaryotes began to multiply and become better adapted to survival out of the water. Prokaryote lineages had probably colonized the land as early as 2.6 Ga even before the origin of the eukaryotes. For a long time, the land remained barren of multicellular organisms. The supercontinent Pannotia formed around 600 Ma and then broke apart a short 50 million years later. Fish, the earliest vertebrates, evolved in the oceans around 530 Ma. A major extinction event occurred near the end of the Cambrian period, which ended 488 Ma. Several hundred million years ago, plants (probably resembling algae) and fungi started growing at the edges of the water, and then out of it. The oldest fossils of land fungi and plants date to 480–460 Ma, though molecular evidence suggests the fun...

The rate of the evolution of life as recorded by fossils accelerated in the Cambrian period (542–488 Ma). The sudden emergence of many new species, phyla, and forms in this period is called the Cambrian Explosion. The biological fomenting in the Cambrian Explosion was unpreceded before and since that time. Whereas the Ediacaran life forms appear yet primitive and not easy to put in any modern group, at the end of the Cambrian most modern phyla were already present. The development of hard body parts such as shells, skeletons or exoskeletons in animals like molluscs, echinoderms, crinoids and arthropods (a well-known group of arthropods from the lower Paleozoic are the trilobites) made the preservation and fossilization of such life forms easier than those of their Proterozoic ancestors. For this reason, much more is known about life in and after the Cambrian than about that of older periods. Some of these Cambrian groups appear complex but are quite different from modern life; examples...

The natural evolution of the Sun made it progressively more luminous during the Archean and Proterozoic eons; the Sun's luminosity increases 6% every billion years. As a result, the Earth began to receive more heat from the Sun in the Proterozoic eon. However, the Earth did not get warmer. Instead, the geological record seems to suggest it cooled dramatically during the early Proterozoic. Glacial deposits found in South Africa date back to 2.2 Ga, at which time, based on paleomagnetic evidence, they must have been located near the equator. Thus, this glaciation, known as the Makganyene glaciation, may have been global. Some scientists suggest this was so severe that the Earth was totally frozen over from the poles to the equator, a hypothesis called Snowball Earth. The ice age around 2.3 Ga could have been directly caused by the increased oxygen concentration in the atmosphere, which caused the decrease of methane (CH4) in the atmosphere. Methane is a strong greenhouse gas, but wit...

Photosynthesis Evolution Early photosynthetic systems, such as those in green and purple sulfur and green and purple nonsulfur bacteria, are thought to have been anoxygenic, and used various other molecules as electron donors rather than water. Green and purple sulfur bacteria are thought to have used hydrogen and sulfur as electron donors. Green nonsulfur bacteria used various amino and other organic acids as an electron donor. Purple nonsulfur bacteria used a variety of nonspecific organic molecules. The use of these molecules is consistent with the geological evidence that Earth's early atmosphere was highly reducing at that time. Fossils of what are thought to be filamentous photosynthetic organisms have been dated at 3.4 billion years old. The main source of oxygen in the Earth's atmosphere derives from oxygenic photosynthesis, and its first appearance is sometimes referred to as the oxygen catastrophe. Geological evidence suggests that oxygenic photosynthesis, such as tha...

Evolution Evolution is change in the heritable characteristics of biological populations over successive generations. Evolutionary processes give rise to biodiversity at every level of biological organisation, including the levels of species, individual organisms, and molecules. All life on Earth shares a common ancestor known as the last universal common ancestor (LUCA), which lived approximately 3.5–3.8 billion years ago, although a study in 2015 found "remains of biotic life" from 4.1 billion years ago in ancient rocks in Western Australia. In July 2016, scientists reported identifying a set of 355 genes from the LUCA of all organisms living on Earth. Repeated formation of new species (speciation), change within species (anagenesis), and loss of species (extinction) throughout the evolutionary history of life on Earth are demonstrated by shared sets of morphological and biochemical traits, including shared DNA sequences. These shared traits are more similar among species t...

Abiogenesis or biopoiesis or OoL (Origins of Life), is the natural process of life arising from non-living matter, such as simple organic compounds. It is thought to have occurred on Earth between 3.8 and 4.1 billion years ago. Abiogenesis is studied through a combination of laboratory experiments and extrapolation from the characteristics of modern organisms, and aims to determine how pre-life chemical reactions gave rise to life on Earth. The study of abiogenesis involves geophysical, chemical, and biological considerations, with more recent approaches attempting a synthesis of all three. Many approaches investigate how self-replicating molecules, or their components, came into existence. It is generally thought that current life on Earth is descended from an RNA world, although RNA-based life may not have been the first life to have existed. The classic Miller–Urey experiment and similar research demonstrated that most amino acids, the basic chemical constituents of the proteins use...

The origin of water on Earth, or the reason that there is clearly more liquid water on Earth than on the other rocky planets of the Solar System, is not completely understood. There exist numerous more or less mutually compatible hypotheses as to how water may have accumulated on Earth's surface over the past 4.5 billion years in sufficient quantity to form oceans. Comets, trans-Neptunian objects or water-rich meteoroids (protoplanets) from the outer reaches of the asteroid belt colliding with Earth may have brought water to the world's oceans. Measurements of the ratio of the hydrogen isotopes deuterium and protium point to asteroids, since similar percentage impurities in carbon-rich chondrites were found in oceanic water, whereas previous measurement of the isotopes' concentrations in comets and trans-Neptunian objects correspond only slightly to water on Earth. Planetesimals heated by the decay of aluminium. This could cause water to rise to the surface. Recent studies ...

The Late Heavy Bombardment (abbreviated LHB and also known as the lunar cataclysm) is an event thought to have occurred approximately 4.1 to 3.8 billion years (Ga) ago, corresponding to the Neohadean and Eoarchean eras on Earth. During this interval, a disproportionately large number of asteroids are theorized to have collided with the early terrestrial planets in the inner Solar System, including Mercury, Venus, Earth, and Mars. The LHB happened after the Earth and other rocky planets had formed and accreted most of their mass, but still quite early in Earth's history. Evidence for the LHB derives from lunar samples brought back by the Apollo astronauts. Isotopic dating of Moon rocks implies that most impact melts occurred in a rather narrow interval of time. Several hypotheses are now offered to explain the apparent spike in the flux of impactors (i.e. asteroids and comets) in the inner Solar System, but no consensus yet exists. The Nice model is popular among planetary scientist...

Several mechanisms have been proposed for the Moon's formation 4.527 ± 0.010 billion years ago, some 30–50 million years after the origin of the Solar System. Recent research presented by Rick Carlson indicates a slightly lower age of between 4.40 and 4.45 billion years. These mechanisms included the fission of the Moon from Earth's crust through centrifugal force (which would require too great an initial spin of Earth), the gravitational capture of a pre-formed Moon (which would require an unfeasibly extended atmosphere of Earth to dissipate the energy of the passing Moon), and the co-formation of Earth and the Moon together in the primordial accretion disk (which does not explain the depletion of metals in the Moon). These hypotheses also cannot account for the high angular momentum of the Earth–Moon system. The prevailing hypothesis today is that the Earth–Moon system formed as a result of a giant impact, where a Mars-sized body (named Theia) collided with the newly formed p...

The giant-impact hypothesis, sometimes called the Big Splash, or the Theia Impact suggests that the Moon formed out of the debris left over from a collision between Earth and an astronomical body the size of Mars, approximately 4.5 billion years ago, in the Hadean eon; about 20 to 100 million years after the solar system coalesced. The colliding body is sometimes called Theia, from the name of the mythical Greek Titan who was the mother of Selene, the goddess of the Moon. Analysis of lunar rocks, published in 2016, suggests that the impact may have been a direct hit, causing a thorough mixing of both parent bodies. As of 2001 the giant-impact hypothesis is the favoured scientific hypothesis for the formation of the Moon. Supporting evidence includes: Earth's spin and the Moon's orbit have similar orientations. Moon samples indicate that the Moon once had a molten surface. The Moon has a relatively small iron core. The Moon has a lower density than Earth. Evidence exists of simi...

The Hadean is a geologic eon of the Earth, and lies before the Archean. It began with the formation of the Earth about 4.6 billion years ago and ended, as defined by the ICS, 4 billion years ago. The geologist Preston Cloud coined the term in 1972, originally to label the period before the earliest-known rocks on Earth. W. Brian Harland later coined an almost synonymous term: the "Priscoan period". Other, older texts simply refer to the eon as the Pre-Archean. Nonetheless, in 2015, traces of carbon minerals interpreted as "remains of biotic life" were found in 4.1-billion-year-old rocks in Western Australia. In the last decades of the 20th century geologists identified a few Hadean rocks from Western Greenland, Northwestern Canada, and Western Australia. The oldest dated zircon crystals, enclosed in a metamorphosed sandstone conglomerate in the Jack Hills of the Narryer Gneiss Terrane of Western Australia, date to 4.404 ± 0.008 Ga. This zircon is a slight outlier, w...

The early Earth is loosely defined as Earth in its first one billion years, or gigayear. On the geologic time scale, this comprises all of the Hadean eon (starting with the formation of the Earth about 4.6 billion years ago), as well as the Eoarchean (starting 4 billion years ago) and part of the Paleoarchean (starting 3.6 billion years ago) eras of the Archean eon. This period of Earth's history involved the planet's formation from the solar nebula via a process known as accretion. This time period included intense meteorite bombardment as well as giant impacts, including the Moon-forming impact, which resulted in a series of magma oceans and episodes of core formation. After formation of the core, delivery of meteoritic or cometary material in a "late veneer" may have delivered water and other volatile compounds to the Earth. Although little crustal material from this period survives, the oldest dated specimen is a zircon mineral of 4.404 ± 0.008 Ga enclosed in a me...

The oldest material found in the Solar System is dated to 4.5672±0.0006 billion years ago (Gya). By 4.54±0.04 Gya the primordial Earth had formed. The formation and evolution of the Solar System bodies occurred along with those of the Sun. In theory, a solar nebula partitions a volume out of a molecular cloud by gravitational collapse, which begins to spin and flatten into a circumstellar disk, and then the planets grow out of that disk along with the Sun. A nebula contains gas, ice grains, and dust (including primordial nuclides). According to nebular theory, planetesimals formed by accretion, with the primordial Earth taking 10–20 Ma to form. An subject of on-going research is the formation of the Moon, some 4.53 billion years ago. A working hypothesis is that it formed by accretion from material loosed from Earth after a Mars-sized object, named Theia, impacted Earth. In this scenario, the mass of Theia was approximately 10% of that of Earth, it impacted Earth with a glancing blow, ...

Earth (otherwise known as the world, in Greek: Gaia, or in Latin: Terra) is the third planet from the Sun, the densest planet in the Solar System, the largest of the Solar System's four terrestrial planets, and the only astronomical object known to harbor life. According to radiometric dating and other sources of evidence, Earth formed about 4.54 billion years ago. Earth gravitationally interacts with other objects in space, especially the Sun and the Moon. During one orbit around the Sun, Earth rotates about its own axis 366.26 times, creating 365.26 solar days or one sidereal year. Earth's axis of rotation is tilted 23.4° away from the perpendicular of its orbital plane, producing seasonal variations on the planet's surface within a period of one tropical year (365.24 solar days). The Moon is the Earth's only permanent natural satellite; their gravitational interaction causes ocean tides, stabilizes the orientation of Earth's rotational axis, and gradually slows E...

A giant impact between the proto-Earth and a Mars-sized impactor named Theia is the best current theory for the formation of the Moon. Scientists believe that Theia collided with the early Earth and that the Moon was created from the rubble left over from the collision. Researchers have estimated that more than 40% of the Moon-forming debris should have been derived from left over pieces of Theia, but new research by a team of geochemists led by Junjun Zhang at the University of Chicago suggests that the Moon is made mostly of material from early Earth instead. The team analyzed Oxygen isotopes and found that terrestrial and lunar samples were almost identical, which is inconsistent with earlier models. The researchers measured ratios in lunar samples measured by mass spectrometry. After correcting for secondary effects associated with cosmic-ray exposure at the lunar surface, they found that the ratio of the Moon is identical to that of the Earth within about four parts per million, w...