alpha2cen Posted December 7, 2012 Share Posted December 7, 2012 Stars and their planets are formed together from large clouds of matter that collapse into a swirling disc. The star forms at the core and the planets by accreating matter in the disc, as such planets are normally formed already in orbit around their star. But during this process it is possible that some protobodies could get ejected from their birth system and then later on get gravitationally captured by a another star or planet they encounter. The Solar System formed 4.568 billion years ago from the gravitational collapse of a region within a large molecular cloud. This initial cloud was likely several light-years across and probably birthed several stars. As is typical of molecular clouds, this one consisted mostly of hydrogen, with some helium, and small amounts of heavier elements fused by previous generations of stars. As the region that would become the Solar System, known as the pre-solar nebula, collapsed, conservation of angular momentum caused it to rotate faster. The centre, where most of the mass collected, became increasingly hotter than the surrounding disc. As the contracting nebula rotated faster, it began to flatten into a protoplanetary disc with a diameter of roughly 200 AU and a hot, dense protostar at the centre. The planets formed by accretion from this disc, in which dust and gas gravitationally attracted each other, coalescing to form ever larger bodies. Hundreds of protoplanets may have existed in the early Solar System, but they either merged or were destroyed, leaving the planets, dwarf planets, and leftover minor bodies. http://en.wikipedia.org/wiki/Solar_System#Formation_and_evolution Many factors contribute to making current solar system. Is this one of the causes making small planet in the solar system? Link to comment Share on other sites More sharing options...
Spyman Posted December 7, 2012 Share Posted December 7, 2012 Many factors contribute to making current solar system. Is this one of the causes making small planet in the solar system? I am not an expert but I don't think so. Interactions by nearby stars might disturb orbits of bodies in the Oort cloud and cause bombardment on the protoplanets but not likely clearing the disk between them. Protoplanets are thought to form by accreting more and more of the material in their neighborhood by collisions and then the final purging of other planetesimals is done gravitationally by the protoplanets themselves. It is not known with certainty how planets are formed. The prevailing theory is that they are formed during the collapse of a nebula into a thin disk of gas and dust. A protostar forms at the core, surrounded by a rotating protoplanetary disk. Through accretion (a process of sticky collision) dust particles in the disk steadily accumulate mass to form ever-larger bodies. Local concentrations of mass known as planetesimals form, and these accelerate the accretion process by drawing in additional material by their gravitational attraction. These concentrations become ever denser until they collapse inward under gravity to form protoplanets. After a planet reaches a diameter larger than the Earth's moon, it begins to accumulate an extended atmosphere, greatly increasing the capture rate of the planetesimals by means of atmospheric drag. http://en.wikipedia.org/wiki/Planet#Formation A planet (from Ancient Greek αστήρ πλανήτης (astēr planētēs), meaning "wandering star") is a celestial body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals. http://en.wikipedia.org/wiki/Planet "Clearing the neighbourhood of its orbit" is a criterion for a celestial body to be considered a planet in the Solar System. This was one of the three criteria adopted by the International Astronomical Union (IAU) in its 2006 definition of planet. /../ The phrase refers to an orbiting body (a planet or protoplanet) "sweeping out" its orbital region over time, by gravitationally interacting with smaller bodies nearby. Over many orbital cycles, a large body will tend to cause small bodies either to accrete with it, or to be disturbed to another orbit, or to be captured either as a satellite or into a resonant orbit. As a consequence it does not then share its orbital region with other bodies of significant size, except for its own satellites, or other bodies governed by its own gravitational influence. http://en.wikipedia.org/wiki/Cleared_the_neighbourhood 1 Link to comment Share on other sites More sharing options...
swansont Posted December 7, 2012 Share Posted December 7, 2012 ! Moderator Note Split from http://www.scienceforums.net/topic/71407-how-did-planets-end-up-orbiting-the-sun/ alpha2cen, you've been asked a number of times not to hijack threads with your own questions that are only peripherally related. The OP in the thread was not asking about planet formation, per se, so I will ask you again to start new threads when you have something new to discuss. Link to comment Share on other sites More sharing options...
alpha2cen Posted December 8, 2012 Author Share Posted December 8, 2012 I am not an expert but I don't think so. Interactions by nearby stars might disturb orbits of bodies in the Oort cloud and cause bombardment on the protoplanets but not likely clearing the disk between them. Protoplanets are thought to form by accreting more and more of the material in their neighborhood by collisions and then the final purging of other planetesimals is done gravitationally by the protoplanets themselves. It is not known with certainty how planets are formed. The prevailing theory is that they are formed during the collapse of a nebula into a thin disk of gas and dust. A protostar forms at the core, surrounded by a rotating protoplanetary disk. Through accretion (a process of sticky collision) dust particles in the disk steadily accumulate mass to form ever-larger bodies. Local concentrations of mass known as planetesimals form, and these accelerate the accretion process by drawing in additional material by their gravitational attraction. These concentrations become ever denser until they collapse inward under gravity to form protoplanets. After a planet reaches a diameter larger than the Earth's moon, it begins to accumulate an extended atmosphere, greatly increasing the capture rate of the planetesimals by means of atmospheric drag. http://en.wikipedia.org/wiki/Planet#Formation A planet (from Ancient Greek αστήρ πλανήτης (astēr planētēs), meaning "wandering star") is a celestial body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals. http://en.wikipedia.org/wiki/Planet "Clearing the neighbourhood of its orbit" is a criterion for a celestial body to be considered a planet in the Solar System. This was one of the three criteria adopted by the International Astronomical Union (IAU) in its 2006 definition of planet. /../ The phrase refers to an orbiting body (a planet or protoplanet) "sweeping out" its orbital region over time, by gravitationally interacting with smaller bodies nearby. Over many orbital cycles, a large body will tend to cause small bodies either to accrete with it, or to be disturbed to another orbit, or to be captured either as a satellite or into a resonant orbit. As a consequence it does not then share its orbital region with other bodies of significant size, except for its own satellites, or other bodies governed by its own gravitational influence. http://en.wikipedia.org/wiki/Cleared_the_neighbourhood There are many models about current solar system creation. Comet is not a main cause of making the solar system. But some contributed becoming a current shape of the Solar system. The distance between our planets is not the same as other stellar systems. And, the influence of external force against our outer solar system objects have been discussed at the other forum, too. Link to comment Share on other sites More sharing options...
David Levy Posted December 8, 2012 Share Posted December 8, 2012 The core of the spiral galaxy is the only place in the universe which generates a star… Just think about the Hydrogen and Helium.. Put those gases in the space and after one second those gases disappeared. It is similar to the question: where a baby can be born??? As a baby can be only born in the womb, a star can be only be born in the center of the spiral galaxy. This is the only place in the universe where the power of gravity is so strong to press the gas and other matter into a star. All the other theories are pure fantasy… -1 Link to comment Share on other sites More sharing options...
alpha2cen Posted December 8, 2012 Author Share Posted December 8, 2012 (edited) The core of the spiral galaxy is the only place in the universe which generates a star… Just think about the Hydrogen and Helium.. Put those gases in the space and after one second those gases disappeared. It is similar to the question: where a baby can be born??? As a baby can be only born in the womb, a star can be only be born in the center of the spiral galaxy. This is the only place in the universe where the power of gravity is so strong to press the gas and other matter into a star. All the other theories are pure fantasy… To become a stellar, the compression of interstellar gas cloud must be happen. Current thinking is nearby supernova explosion wave gave a big role about the gas cloud compression. I do not think that above idea #1, explains the main cause to become planets in the Solar system. To be a planet, at first, the interstellar gas cloud concentration must be sufficiently high. And, to become a planet , nucleus creation step is needed . In this step a comet might be contributed as a nucleus. Edited December 8, 2012 by alpha2cen -1 Link to comment Share on other sites More sharing options...
D H Posted December 8, 2012 Share Posted December 8, 2012 The core of the spiral galaxy is the only place in the universe which generates a star… Just think about the Hydrogen and Helium.. Put those gases in the space and after one second those gases disappeared. It is similar to the question: where a baby can be born??? As a baby can be only born in the womb, a star can be only be born in the center of the spiral galaxy. This is the only place in the universe where the power of gravity is so strong to press the gas and other matter into a star. All the other theories are pure fantasy… Every bit of this post is nonsense. 1 Link to comment Share on other sites More sharing options...
Klaynos Posted December 8, 2012 Share Posted December 8, 2012 The core of the spiral galaxy is the only place in the universe which generates a star… Just think about the Hydrogen and Helium.. Put those gases in the space and after one second those gases disappeared. It is similar to the question: where a baby can be born??? As a baby can be only born in the womb, a star can be only be born in the center of the spiral galaxy. This is the only place in the universe where the power of gravity is so strong to press the gas and other matter into a star. All the other theories are pure fantasy… ! Moderator Note Please do not respond to mainstream threads with your own speculations/ideas. Keep them to their own threads in the correct area of the forum. Link to comment Share on other sites More sharing options...
David Levy Posted December 8, 2012 Share Posted December 8, 2012 (edited) I have alraedy did Update stady state Theory advertising link to other thread removed Edited December 8, 2012 by Phi for All Removed link driving traffic to another thread Link to comment Share on other sites More sharing options...
mooeypoo Posted December 8, 2012 Share Posted December 8, 2012 I have alraedy did Update stady state Theory advertising link to other thread removed Then keep that discussion in that forum and do not discuss it in other threads. That is called thread hijacking, and it is against our rules. Insisting on doing it again after being warned is called trolling, which is also against our rules. Don't answer moderation posts. If you want to argue your point against moderation note, use the report button so another staff member can go over it without derailing the thread even further. Link to comment Share on other sites More sharing options...
ACG52 Posted December 8, 2012 Share Posted December 8, 2012 The core of the spiral galaxy is the only place in the universe which generates a star The usual ignorant nonsense. Link to comment Share on other sites More sharing options...
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