what is the importance of accretion in the formation of solar system?
545969
A cretin is not important at all...\n\nWait, bad joke, very bad joke.  \n\nActually, accretion is absolutely essential.  Accretion means "Growth or increase in size by gradual external addition, fusion, or inclusion"  When the initial protodisk that eventually became the sun and planets started to come together, gravity pulled atoms and dust specks toward each other.  It was accretion - the growth by gradual addition - that allowed those specks to become pebbles and pebbles to become rocks and rocks to become bigger and bigger until you had the sun, the earth, planets, moons, and all those other things that make up the solar system.\n\nWithout accretion it would all still be a loose cloud circling around in space.  And without a cretin, we'd all be better... wait - SORRY!
468438
Earth formed as part of the birth of the solar system: what eventually became the solar system initially existed as a large, rotating cloud of dust and gas. It was composed of hydrogen and helium produced in the Big Bang, as well as heavier elements produced by stars long gone. Then, about 4.6 billion years ago (fifteen to thirty minutes before our imaginary clock started), a nearby star probably became a supernova. The explosion sent a shock wave toward the solar nebula and caused it to contract. As the cloud continued to rotate, gravity and inertia flattened the cloud into a disc, perpendicular to its axis of rotation. Most of the mass concentrated in the middle and began to heat up. Meanwhile, as gravity caused matter to condense around dust particles, the rest of the disc started to break up into rings. Small fragments collided and became larger fragments.[2] These included one collection approximately 150 million kilometers from the center: Earth. As the Sun condensed and heated, fusion began, and the resulting solar wind cleared out most of the material in the disc that had not already condensed into larger bodies.
746904
1.  At this stage of the life of the Solar System, there are not many large meteorites left to intersect the Earth's orbit.  The gravitational fields of the large outer planets, especially Jupiter, have had the effect of either hoovering them up, or shepherding them into stable orbits in the asteroid belt.\n\n2.  The Earth is small compared to the separation between large meteorites.  If it was twice the diameter, it would get four times as many impacts, just like an archery target.\n\n3.  Large meteorites reach the surface with so much energy that they usually disintegrate, instead of staying in one piece.  The fragments can disappear by erosion much quicker than the crater does.
330346
As of right now, scientists believe that planets are by-products of the formation of stars. A star is formed when particles in a swirling cloud of dust and gas (a nebula) get closer and closer together and begin to combine hydrogen atoms to form helium atoms. This produces lots of energy (which is why stars, like the Sun, shine). Planets are the leftover "clumps" of dust and gas that do not produce their own energy.
543004
Technically, the general rotation direction of the Sun and most planets is a leftover from the original solar nebula from which the Solar System formed.  As the planets and Sun coalesced, they retained the rotation direction of the original nebula.\n\nDuring the coalescence phase, asteroid-size chunks collided and stuck together.  As more and more of these chunks collected, the planets grew in size.  However, these chunks not only brought mass to the mix, they also brought momentum.  Since most of the materials were probably all travelling in more or less the same direction, the general rotation direction of the growing planets remained the same.\n\nIn the case of Venus and Uranus, it is suspected that a major collision between the planet and another body literally tipped the planets over due to an off-center orientation of the collision.  Uranus tipped over on its side, probably due to its size relative to the other body.  Venus, being smaller, tipped so far over that its rotation was reversed.
84059
The boundary of the solar system is probably very loose indeed. You could perhaps mean where the Suns gravitational influence is canceled by other stars or where the solar wind no longer reaches. Dust and space is most likely what you'll find. Space is pretty boring, trying to understand it is not :)
156002
The solar system was formed from the debris of earlier stars.  As the dust and particles collided and formed bigger chunks, they began to exert a gravitational attraction to each other.  These particles began to rotate around a central point (what would eventually become the sun).\n\nThe sun was formed from the majority of the matter.  Once the sun reached critical mass, it started the fusion reaction that powers the sun still to this day (Fusion of hydrogen into helium).\n\nThe gravitational pull of the sun caused the terrestrial (or rocky) planets to form from the heavier debris that was drawn in closer (and in a faster orbit).  These planets are Mercury, Venus, Earth and Mars.\n\nThe lighter gasses didn't have as much gravitational attraction as the heavier minerals and these gasses formed the gas giants of our solar system (much further out away from the sun and in a slower orbit).  These planets are Jupiter, Saturn, Uranus and Neptune.\n\nThe last planet, Pluto, is an exception.  It was formed of the left-over debris at the outer edge of the solar system.  It reallys isn't a true planet, more of a Keiper belt object; like a large asteroid.
50650
From an astronomy standpoint...\n\nThe Sun and the planets formed out of the same protostellar material.  This protostellar material was mainly hydrogen and helium with trace amounts of heavier elements produced by past generations of stars.  Something like a shock wave of other disturbance in space causes the material to compress and become gravitationally unstable.  The contraction of the protostar begins.\n\nThe majority of the material formed the Sun the rest of it was essentially stretched out in a disk.  Local gravitational unstabilities over time coalesce to form clumps of matter in the disk.  These clumps of matter are the protoplanets.  Again over time these clumps sweep out material in the disk of the solar system and build to large masses that are the present day planets.   \n\nThat's planet formation in a nutshell...at least that's how astrophysics sees the formation of Earth like planets.
552214
Seeing as our solar system must have been formed from the last dying sneeze of a star (as there are very heavy elements that couldn't be present otherwise), thats where we came from. We are basically star snot.
744404
The Sun is the most prominent feature in our solar system. It is the largest object and contains approximately 98% of the total solar system mass. One hundred and nine Earths would be required to fit across the Sun's disk, and its interior could hold over 1.3 million Earths. The Sun's outer visible layer is called the photosphere and has a temperature of 6,000°C (11,000°F). This layer has a mottled appearance due to the turbulent eruptions of energy at the surface. \nSolar energy is created deep within the core of the Sun. It is here that the temperature (15,000,000° C; 27,000,000° F) and pressure (340 billion times Earth's air pressure at sea level) is so intense that nuclear reactions take place. This reaction causes four protons or hydrogen nuclei to fuse together to form one alpha particle or helium nucleus. The alpha particle is about .7 percent less massive than the four protons. The difference in mass is expelled as energy and is carried to the surface of the Sun, through a process known as convection, where it is released as light and heat. Energy generated in the Sun's core takes a million years to reach its surface. Every second 700 million tons of hydrogen are converted into helium ashes. In the process 5 million tons of pure energy is released; therefore, as time goes on the Sun is becoming lighter. \n\n \n\nThe chromosphere is above the photosphere. Solar energy passes through this region on its way out from the center of the Sun. Faculae and flares arise in the chromosphere. Faculae are bright luminous hydrogen clouds which form above regions where sunspots are about to form. Flares are bright filaments of hot gas emerging from sunspot regions. Sunspots are dark depressions on the photosphere with a typical temperature of 4,000°C (7,000°F). \n\nThe corona is the outer part of the Sun's atmosphere. It is in this region that prominences appears. Prominences are immense clouds of glowing gas that erupt from the upper chromosphere. The outer region of the corona stretches far into space and consists of particles traveling slowly away from the Sun. The corona can only be seen during total solar eclipses. (See Solar Eclipse Image). \n\nThe Sun appears to have been active for 4.6 billion years and has enough fuel to go on for another five billion years or so. At the end of its life, the Sun will start to fuse helium into heavier elements and begin to swell up, ultimately growing so large that it will swallow the Earth. After a billion years as a red giant, it will suddenly collapse into a white dwarf -- the final end product of a star like ours. It may take a trillion years to cool off completely.
765007
Astronomy (Greek: αστρονομία = άστρον + νόμος, astronomia = astron + nomos, literally, "law of the stars") is the science of celestial objects (e.g., stars, planets, comets, and galaxies) and phenomena that originate outside the Earth's atmosphere (e.g., auroras and cosmic background radiation). It is concerned with the evolution, physics, chemistry, and motion of celestial objects, as well as the formation and development of the universe.\n\nhttp://en.wikipedia.org/wiki/Astronomy\n\n----------------------------------------------------------------------------\n\nGeology (from Greek γη- (ge-, "the earth") and λογος (logos, "word", "reason"))is the science and study of the solid matter of a celestial body, its composition, structure, physical properties, history and the processes that shape it. It is one of the Earth sciences.\n\nhttp://en.wikipedia.org/wiki/Geology\n\n---------------------------------------------------------------------------\n\nChemistry (from Greek χημεία khemeia[1] meaning "alchemy") is the science of matter at the atomic to molecular scale, dealing primarily with collections of atoms, such as molecules, crystals, and metals. Chemistry deals with the composition and statistical properties of such structures, as well as their transformations and interactions to become materials encountered in everyday life. Chemistry also deals with understanding the properties and interactions of individual atoms with the purpose of applying that knowledge at the macroscopic level. According to modern chemistry, the physical properties of materials are generally determined by their structure at the atomic scale which is determined by the properties and energies of the interactions.\n\nhttp://en.wikipedia.org/wiki/Chemistry\n\n-----------------------------------------------------------------------------\n\nPhysics (from the Greek, φύσις (phúsis), "nature" and φυσική (phusiké), "knowledge of nature") is the science concerned with the discovery and understanding of the fundamental laws which govern matter, energy, space and time. That is, physics deals with the elementary constituents of the Universe and their interactions, as well as the analysis of systems which are best understood in terms of these fundamental principles. Physics is a study of the inorganic, physical world, as opposed to the organic world of biology, physiology, etc. Physics overlaps with chemistry concerning the electro-chemical interactions of substances.\n\nhttp://en.wikipedia.org/wiki/Physics\n\n--------------------------------------------------------------------------------\n\nMeteorology is the interdisciplinary scientific study of the atmosphere that focuses on weather processes and forecasting. Meteorological phenomena are observable weather events which illuminate and are explained by the science of meteorology. Those events are bound by the variables that exist in Earth's atmosphere. They are temperature, pressure, water vapor, and the gradients and interactions of each variable, and how they change in time. The majority of Earth's observed weather is located in the troposphere.\n\nMeteorology, climatology, atmospheric physics, and atmospheric chemistry are sub-disciplines of the atmospheric sciences. Meteorology and hydrology comprise the interdiscplinary field of hydrometeorology.\n\nhttp://en.wikipedia.org/wiki/Meteorology
249875
The sun is a big fire at the center of the of the solar system. The planets are balls that float around the sun. if the planet is to close to the sun nothing can live on it, It is too hot. If the planet is to far away from the sun nothing can live on it, it is too cold. On earth it is just right. Our atmosphere protects us from all the other stuff floating around. a meteorite is a rock that would hit the earth if our atmosphere did not protect us. the moon is a ball floating around a planet. Our moon is called "Luna" it has no atmosphere and lots of meteors hit it.
220183
Simple way to look at this perinnial question. One solar system. One planet like earth froms. Sustains life. Universe is filled with billions of stars. Some the size of our Sun. Some have planets revolving round them. Like earth too. Take a wild guess and u wont be wrong. \n;-)
73511
GREAT QUESTION !!!\n\nYour question takes us back to the very beginning of our Solar System. The Earth, Sun, and the other planets began to form from a spinning cloud of cosmic debris called a Nubula. With the Sun at the center, everything else that was left over became the Solar System we see today. \nBut the Early Solar System just had small and large clumps of matter orbiting the center. Through eons of time, the larger clumps grew bigger because the smaller clumps hit them. Eventually, the Solar System was a choas of hundreds of little "planets" surronded by and emense plane of orbiting debris. At some point, the bigger objects became large enough to gravitationally pull in the rest of the debris around it. These objects grew much quicker than the rest, but each new impact made them even bigger and capable of pulling in even more rock and debris. \nLet's now just concentrate on the Earth-Moon system, eventhough we use crater counts to date any planet or moon anywhere in the Solar System that we can:\n Once the rocky inner planets formed, it's believed that the early Earth was smacked by a Mars sized body which totally reformed the Earth and created the Moon. Objects still rained down on the early Earth and Moon, however. Some of the largest impacts on the Moon are the oldest and filled up with lava. This is the "Man on the Moon" face we see today. Remember that the Earth was being hit more often than the Moon at this time because it had a stronger gravity, but most of these impacts aren't visable today because of weathering (rain, wind, etc.), plate techtonics, volcanic eruptions, the creation of Oceans, and stuff like that. But the Moon had no atmosphere and it cooled a lot quicker than the Earth did, because it was smaller. \nOnce the Solar System got to a point that it wasn't "swimming" in a cloud of debris, we basically had the nine planets left as the survivors of this early bombardment. This left the Moon scarred with all kinds of impact craters which would be the oldest craters we see today.\nFinally there came a point where most of the larger rocks (asteroids) floating around had been absorded by the planets, and this left just the smaller chunks of rock. This is the start of the second phase of cratering where most of this remaining debris eventually was "sucked up" by the Earth and Moon (and planets). This second phase ended about 3 billion years ago. The third phase we are still in today with occasional impacts occuring, but nothing like the first two stages.\n\nSo how does this answer your question?????\n\nLet's just concentrate on the Moon now: \n Imagine the Moon early in the first phase just covered with shoulder to shoulder craters. Each new crater formed over the top of older ones. In other words, when you see a large crater today that has smaller ones inside it, you know that the large impact had to occur before the smaller ones. If this wasn't true, the larger crater would have wiped out any evidence of the smaller ones, right?\n Then there came the point when the lava I mentioned earlier covered up the lower impact basins we see today as the "Man on the Moon." We can tell--just from counting craters-- that this occured afer the first phase, because the lava covered all of these earlier shoulder to shoulder impacts and left relatively smooth plains. Impacts still happened on the plains, but nothing like in the first phase of cratering.\n So you can begin to see that the older an area on the Moon is, the larger the crater density. That plot of ground was around when the first phase of cratering was still going on. It's covered with crater after crater of different sizes with no smooth, craterless areas at all!  Any area on the Moon that has a lower crater density would of had to have been reworked by larger impacts or covered by lava, AND IS, THEREFORE YOUNGER THAN HEAVILY CRATERED TERRAIN.\n The only other "weathering&quot
1050263
Since the diameter of the sun is 864,000 miles and the diameter of a typical basketball is about 9½ inches (they vary from 9¼ to 9½ inches), if we divide 864,000 miles by 9½ inches, we discover that in our model 1 inch represents roughly 91,000 miles. To see how everything else fits into our model we need only divide any other dimensions of our solar system by 91,000. For example, Mercury, on the average, is about 36,250,000 miles from the sun. If we divide 36,250,000 by 91,000 we find that in our model it is roughly 398 inches-or about 33 feet away from the basketball. And, if we divide Mercury' s diameter of 3050 miles by 91,000, we find that the Mercury in our model is just .034 inches wide-about 1/30 inch. This is smaller than a typical BB. \n\nIf you know your stride (mine is about 2½ feet) you can put the basketball on the ground and pace this off. Better yet, if you have access to a football field at a local high school or college, place a basketball on one of the goal lines and walk out to the 11 yard line. This is where Mercury is.\n\nScientists believe that the solar system was formed when a cloud of gas and dust in space was disturbed, maybe by the explosion of a nearby star (called a supernova). This explosion made waves in space which squeezed the cloud of gas and dust. Squeezing made the cloud start to collapse, as gravity pulled the gas and dust together, forming a solar nebula. Just like a dancer that spins faster as she pulls in her arms, the cloud began to spin as it collapsed. Eventually, the cloud grew hotter and denser in the center, with a disk of gas and dust surrounding it that was hot in the center but cool at the edges. As the disk got thinner and thinner, particles began to stick together and form clumps. Some clumps got bigger, as particles and small clumps stuck to them, eventually forming planets or moons . Near the center of the cloud, where planets like Earth formed, only rocky material could stand the great heat. Icy matter settled in the outer regions of the disk along with rocky material, where the giant planets like Jupiter formed. As the cloud continued to fall in, the center eventually got so hot that it became a star, the Sun, and blew most of the gas and dust of the new solar system with a strong stellar wind. By studying meteorites, which are thought to be left over from this early phase of the solar system, scientists have found that the solar system is about 4,600 million years old!
448217
It goes back to when the solar system was formed.  The sun (and the planets, for that matter) were formed when a gigantic cloud of gas and dust collapsed.  When that cloud collapsed, it had something called 'angular momentum', which really just means that it was spinning a little bit.  When a large, slowly spinning thing collapses to something smaller, the rate of rotation speeds up (think about an ice skater that pulls her arms in...she spins up!).  Anyway, so now we have all this gas and dust in a disk that's orbiting the new Sun.  The dust eventually forms into planets.  As the dust collapses into new planets, the same thing happens, and the planets start spinning themselves.  So basically, the earth and moon and whatnot spin because of angular momentum.  I hope this made sense/helped!
662818
Solar system  \n\nThe solar system comprises our Sun and the retinue of celestial objects gravitationally bound to it. Traditionally, this is said to consist of the Sun, nine planets and their 158 currently known moons; however, a large number of other objects, including asteroids, meteoroids, planetoids, comets, and interplanetary dust, orbit the Sun as well.