Nebular hypothesis

planet formationplanetary formationformationplanetscore formation modelsformation of planetsnebular theorynew stars and planets are formedplanetaryprotosolar nebula
The nebular hypothesis is the leading theory, amongst scientists, which states that the planets were formed out of a cloud of material associated with a youthful sun, which was slowly rotating.wikipedia
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Formation and evolution of the Solar System

solar nebulaformation of the Solar Systemoutward
It is the most widely accepted model in the field of cosmogony to explain the formation and evolution of the Solar System (as well as other planetary systems).
This model, known as the nebular hypothesis was first developed in the 18th century by Emanuel Swedenborg, Immanuel Kant, and Pierre-Simon Laplace.

Immanuel Kant

KantKantianKant, Immanuel
The theory was developed by Immanuel Kant and published in his Allgemeine Naturgeschichte und Theorie des Himmels ("Universal Natural History and Theory of the Heavens"), published in 1755 and then modified in 1796 by Pierre Laplace. Immanuel Kant, familiar with Swedenborg's work, developed the theory further in 1755, publishing his own Universal Natural History and Theory of the Heavens, wherein he argued that gaseous clouds (nebulae) slowly rotate, gradually collapse and flatten due to gravity, eventually forming stars and planets.
In the Universal Natural History, Kant laid out the Nebular hypothesis, in which he deduced that the Solar System had formed from a large cloud of gas, a nebula.

Pierre-Simon Laplace

LaplacePierre Simon LaplacePierre-Simon de Laplace
Pierre-Simon Laplace independently developed and proposed a similar model in 1796 in his Exposition du systeme du monde.
He restated and developed the nebular hypothesis of the origin of the Solar System and was one of the first scientists to postulate the existence of black holes and the notion of gravitational collapse.

Planetary system

planetary systemssolar systemssystem
It is the most widely accepted model in the field of cosmogony to explain the formation and evolution of the Solar System (as well as other planetary systems).
Observations using the Spitzer Space Telescope indicate that extremely massive stars of spectral category O, which are much hotter than the Sun, produce a photo-evaporation effect that inhibits planetary formation.

Thomas Chrowder Chamberlin

Thomas C. ChamberlinT.C. ChamberlinThomas Chamberlin
Later in 1900, Thomas Chrowder Chamberlin and Forest Ray Moulton considered that a wandering star approach the sun.
In 1905, Chamberlin and Forest Ray Moulton developed a theory of the formation of the solar system that challenged the Laplacian nebular hypothesis.

Jupiter

JovianGioveplanet Jupiter
Jupiter- and Saturn-like planets are thought to accumulate the bulk of their mass during only 10,000 years.
The presence of a core during at least part of Jupiter's history is suggested by models of planetary formation that require the formation of a rocky or icy core massive enough to collect its bulk of hydrogen and helium from the protosolar nebula.

Emanuel Swedenborg

SwedenborgEmmanuel SwedenborgSwedenborg's Angels
There is evidence that Emanuel Swedenborg first proposed parts of the nebular theory in 1734.
He also outlined his cosmology, which included the first presentation of his nebular hypothesis.

Proplyd

proplydsprotoplanetary disk
Star formation is a complex process, which always produces a gaseous protoplanetary disk (proplyd) around the young star.
Current models show that the metallicity of the star and proplyd, along with the correct planetary system temperature and distance from the star, are keys to planet and planetesimal formation.

Planetary migration

migrationmigrating Neptunemigrated
Another potential problem of giant planet formation is their orbital migration.
This may affect the formation of the cores of the giant planets (which have masses of the order of 10 Earth masses), if those planets form via the core-accretion mechanism.

Planetesimal

planetesimalsasteroid impactsplanetessimal
The grains eventually may coagulate into kilometer-sized planetesimals.
While the name is always applied to small bodies during the process of planet formation, some scientists also use the term planetesimal as a general term to refer to many small Solar System bodies – such as asteroids and comets – which are left over from the formation process.

Exoplanet

extrasolar planetexoplanetsplanet
While originally applied only to the Solar System, the SNDM was subsequently thought by theorists to be at work throughout the Universe; as of astronomers have discovered extrasolar planets in our galaxy.
Astronomers were surprised by these "hot Jupiters", because theories of planetary formation had indicated that giant planets should only form at large distances from stars.

Protoplanetary disk

protoplanetary discprotoplanetary disksprotoplanetary discs
Star formation is a complex process, which always produces a gaseous protoplanetary disk (proplyd) around the young star.

Frost line (astrophysics)

frost linesnow lineice line
It is thought to occur beyond the frost line, where planetary embryos mainly are made of various types of ice.

Streaming instability

streaming instabilities
Another possible mechanism for the formation of planetesimals is the streaming instability in which the drag felt by particles orbiting through gas creates a feedback effect causing the growth of local concentrations.
The growth of the largest planetesimals then accelerates, as gravitational focusing increases their effective cross-section, resulting in runaway accretion forming the larger asteroids.

Nebula

nebulaediffuse nebulanebulosity
Immanuel Kant, familiar with Swedenborg's work, developed the theory further in 1755, publishing his own Universal Natural History and Theory of the Heavens, wherein he argued that gaseous clouds (nebulae) slowly rotate, gradually collapse and flatten due to gravity, eventually forming stars and planets.

Galaxy

galaxiesgalacticgalactic nuclei
While originally applied only to the Solar System, the SNDM was subsequently thought by theorists to be at work throughout the Universe; as of astronomers have discovered extrasolar planets in our galaxy.
The cycle of stellar birth and death slowly increases the abundance of heavy elements, eventually allowing the formation of planets.

History of Earth

Earth's historyhistory of the EarthEarth history
The standard model for the formation of the Solar System (including the Earth) is the solar nebula hypothesis.

Hot Jupiter

hot JupitersPuffy planetultra-short period planet
The latter case corresponds to the so-called hot Jupiters, which are likely to have stopped their migration when they reached the inner hole in the protoplanetary disk.
In the migration hypothesis, a hot Jupiter forms beyond the frost line, from rock, ice, and gases via the core accretion method of planetary formation.

Asteroid belt

main-beltMain beltmain-belt asteroid
Some of the embryos, which originated in the asteroid belt, are thought to have brought water to Earth.
A hypothesis to the asteroid belt creation is that in general, in the Solar System, a planetary formation is thought to have occurred via a process comparable to the long-standing nebular hypothesis: a cloud of interstellar dust and gas collapsed under the influence of gravity to form a rotating disc of material that then further condensed to form the Sun and planets.

Pebble accretion

Another possible solution is the growth of the cores of the giant planets via pebble accretion.
The formation of the gas giants is a long-standing problem in planetary science.

Exocomet

exocometscometsexo-comets
Observations of comets, and especially exocomets, improve our understanding of planet formation.

Accretion (astrophysics)

accretionaccretingaccreted
The friction and collision of particles led to formation of a disk-shaped cloud and the planets were formed through the process of accretion.
The currently favored formation mechanism is that of the nebular hypothesis, which states that comets are probably a remnant of the original planetesimal "building blocks" from which the planets grew.

Sun

solarSolThe Sun
The nebular hypothesis is the leading theory, amongst scientists, which states that the planets were formed out of a cloud of material associated with a youthful sun, which was slowly rotating.

Forest Ray Moulton

MoultonForest R. MoultonMoulton, Forest Ray
Later in 1900, Thomas Chrowder Chamberlin and Forest Ray Moulton considered that a wandering star approach the sun.

Cosmogony

origin of the universecosmogonicalcosmogonic
It is the most widely accepted model in the field of cosmogony to explain the formation and evolution of the Solar System (as well as other planetary systems).