"The nebular hypothesis 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)."
The process of how planets form and how they evolve.
Protoplanetary disks: The disks of gas and dust surrounding young stars that are responsible for the formation of planets.
Accretion: The process by which particles come together and grow into larger bodies.
Dust grain growth: The earliest stage of accretion, during which micrometer-sized grains grow due to collisions and sticking.
Planetesimal formation: Intermediate stage of accretion where the dust grows enough to form solid bodies tens of kilometers in size.
Formation of terrestrial planets: The process by which small rocky planets such as Earth are formed through collisions and accretion of planetesimals.
Formation of gas giants: The process by which large gas giants such as Jupiter are formed through the accumulation of gas onto a rocky core.
Migration: The movement of planets in a protoplanetary disk due to gravitational interactions with gas and other planets.
Late stages of planetary formation: The stage where planets undergo significant changes in their structure and composition due to impact cratering and differentiation.
Habitability and exoplanet formation: The search for planets beyond our solar system that could potentially support life as we know it.
Astrobiology: The study of the emergence, evolution, distribution, and future of life in the universe, including the search for extraterrestrial life.
Nebula Collapse: This is the traditional model of planet formation, where a cloud of gas and dust collapses due to gravity and forms a protoplanetary disk. The disk then coalesces into planets through a process of accretion.
Gravitational Instability: In this model, the protoplanetary disk itself becomes unstable due to gravity and breaks up into clumps that become planets.
Giant Impact: This model proposes that Earth was formed after a large planetesimal collided with the proto-Earth. The impact created a debris disk which later coalesced into the Moon and Earth.
Capture: In this model, a planet forms independently in its own orbit around the star, but is then captured by another planet’s gravitational field and becomes a moon or a companion planet.
Tidal: This model proposes that a planet forms close to its star and is tidally locked, causing a large tidal bulge to form which eventually separates from the planet and becomes a moon.
Disk Instability: In this model, the protoplanetary disk is so massive and dense that it becomes unstable and collapses directly into one or more planets.
Pebble Accretion: A relatively new model, where small icy or rocky particles, called pebbles, gently drift towards their parent star, sticking together and growing larger, ultimately growing into planetesimals that become planets.
"The theory was developed by Immanuel Kant and published in his Universal Natural History and Theory of the Heavens (1755) and then modified in 1796 by Pierre Laplace."
"The widely accepted modern variant of the nebular theory is the solar nebular disk model (SNDM) or solar nebular model."
"The widely accepted modern variant of the nebular theory is the solar nebular disk model (SNDM) or solar nebular model. It offered explanations for a variety of properties of the Solar System, including the nearly circular and coplanar orbits of the planets, and their motion in the same direction as the Sun's rotation."
"According to the nebular theory, stars form in massive and dense clouds of molecular hydrogen—giant molecular clouds (GMC). These clouds are gravitationally unstable, and matter coalesces within them to smaller denser clumps, which then rotate, collapse, and form stars."
"Star formation is a complex process, which always produces a gaseous protoplanetary disk (proplyd) around the young star."
"A Sun-like star usually takes approximately 1 million years to form, with the protoplanetary disk evolving into a planetary system over the next 10–100 million years."
"The grains eventually may coagulate into kilometer-sized planetesimals."
"Near the star, the planetary embryos go through a stage of violent mergers, producing a few terrestrial planets."
"The last stage takes approximately 100 million to a billion years."
"The formation of giant planets is thought to occur beyond the frost line, where planetary embryos mainly are made of various types of ice."
"Some embryos appear to continue to grow and eventually reach 5–10 Earth masses—the threshold value, which is necessary to begin accretion of the hydrogen–helium gas from the disk."
"Jupiter- and Saturn-like planets are thought to accumulate the bulk of their mass during only 10,000 years."
"The accretion stops when the gas is exhausted."
"The formed planets can migrate over long distances during or after their formation."
"Ice giants such as Uranus and Neptune are thought to be failed cores, which formed too late when the disk had almost disappeared."
"A Sun-like star usually takes approximately 1 million years to form, with the protoplanetary disk evolving into a planetary system over the next 10–100 million years."
"Star formation is a complex process, which always produces a gaseous protoplanetary disk (proplyd) around the young star."
"These clouds are gravitationally unstable, and matter coalesces within them to smaller denser clumps, which then rotate, collapse, and form stars."
"Star formation is a complex process, which always produces a gaseous protoplanetary disk (proplyd) around the young star. This may give birth to planets in certain circumstances, which are not well known."