how do planets stay suspended in space.?
599240
Part of the problem is that word "suspended."  It sounds like the planets are "suspended" *from* something, which is not true.  That's why I worry about the mobile idea, with planets "hanging" from coat hangers, as it just reinforces that idea.\n\nThe other thing is that the motion of the planets (their orbit around the sun) is an important ingredient.  They are far enough away that we can't see how fast they are moving.  So they seem to be quite still in the sky (like stars) ... again they *appear* "suspended."  Again, a hanging mobile just reinforces the notion that all the planets are perfectly still.  (BTW, this is why I think every parent should teach a child to find a couple of planets in the sky every few evenings, so the child gets the notion of how it changes position relative to the constellations.  Mars is always really easy to spot, and these days, Saturn is really bright!  That alone can get a child hooked on stargazing, and on science in general!)\n\nHowever, all that said, the mobile idea (styrofoam balls hanging from string) is not a bad one for illustrating the concept of the solar system.  I would just recommend getting it rotating even a little bit to illustrate the idea that the planets are *orbiting* the sun ... they are *moving*.  That is the key lesson I would want a 6-year-old to take away from the project (although what's even more important is that he have fun doing it, and that he asks a lot of questions ... the point really, is to make science fun). \n\nThe actual answer to your "how" question (in case your son really wants to know) is: balanced forces.  The planets have *two* forces acting on them:  (1) the gravity of the sun pulling them inward; and (2) the centrifugal force caused by the speed of their orbit, pushing them out.  These two forces are just balanced enough to keep the planets from falling into the sun, or flying into space.  So if your son were a little older (say 10 or 11) I would try to incorporate elements in the project that represent these two forces.  I have some ideas (and I can present them if you like), but this would be more involved than you probably need to get.\n\nGood luck!
4539
These answers "seem" correct. But Im not sure thats really the case. Within our solar system there is still gravity. What do you think is holding all the planets in place? Perhaps between systems that might be more true.\n\nThe problem is getting a large mass moving fast enough to really be productive. You still need loads of energy to get a real spaceship moving. We just dont have that tech yet. \n\nRight now scientists are working on a plasma engine. Check it out.
1162285
Aircrafts' wings gives the aircraft lift (i.e. shaped so that when wind passes through, it will be pushed up), and once a certain velocity is reached, the upwards lift is enough to counteract the forces of gravity (and exceed it), and thus they fly.\n\nSpaceships achieves escape velocity to escape from the Earth's gravitation (or at least far enough for the space ship to reach orbit). Then, at the orbit, it orbits earth at a certain velocity which gives it enough velocity to counteract the remaining attraction from Earth's gravity, hence it stays in space.
365070
they move around the sun by the gravitational force of sun,and their own centrifugal force,as moon rotates ,or artificial staellites rotate around the earth.also,sun has got such powerful gravity that u cant lift ur foot on sun's surface due to its pull.now the planets also have centrifugfal force which prevents them from rushing into the sun,the closer a planet,the faster it should rotate to balane te gravitational pull of sun and its centrifugal force,dats y mercury rotates with a speed of aroud 29 miles per second.this speed decreases with da increases in distance from da sun.its a perfectly balanced system
1022705
The sun keeps the planets in an unwavering orbit, which keeps the hunks of rock from spilling out into the universe. As time goes on, the sun expands, but not even noticeably for millions of years, which will in time envelop the planets around it, and implode into a white dwarf (dead star).
348014
The particles that make up the rings of Saturn don’t get pulled down to the planet because they orbit the planet.  They remain in orbit for the same reason the Moon or the Space Shuttle remain in orbit around Earth.  In fact, you can think of them as billions of tiny “moonlets”:  they don’t sit still but instead revolve around the planet in predictable (although often complicated) orbits.\n\nAny orbit is a balance between gravity and the motion of the orbiting body.  Objects close to the parent body must orbit more quickly to counteract the stronger pull of gravity—for example, Mercury moves faster in its orbit around the Sun than Earth does—but any orbit constitutes an equilibrium between gravity and momentum.\n\nThat said, Saturn’s rings represent a complicated example of this kind of equilibrium.  Not only does one have to consider the gravitational attraction of Saturn itself, but also of its major moons (Titan, for exampl) and all the aforementioned “moonlets” spinning around the planet.  The results are often surprising:  we see “shepherd” moons that keep rings herded in place, strange propeller-like structures, and even braided rings!  (Links below to some images of these oddities.)\n\nBut the short answer to your question is that the rings, made up of billions of particles, remain constantly in motion, counteracting the pull of gravity.\n\n\nRyan Wyatt\nRose Center for Earth & Space
516685
gravity shows them to move and rotate. the hubble space telescope has pics that show it in time lapse of course.
1041594
Things that are orbiting our planet are in a state of constant "free fall". That is why they appear to be weightless. The force of gravity is still very high on the astronaut.
882349
unfortunately the 2 previous answers are wrong you do still have weight in space!!!\n\nweight = grav field strength x mass\n\nand everywhere in space has some grav field strength! it may be very weak in some places but it's still there. remember this is what keeps all the planets orbiting the sun, and indeed all the stars orbiting their galaxies.\n\nhypothetically you might argue that at some singular point in space there might be a place where the grav fields of all objects with mass are cancelled out, leaving you with a zero field, but this point would wildly fluctuate in position depending on teh motions and interactions of every mass object in the universe.\n\nso the mass of said astronaught is 75xg  \nwhere g is the gravitational field strength at that point in space
43539
Planets seem to be spheres, not cubes or cylinders or oddball rocky shapes.  Some smaller bodies such as asteroids or Mars moons Phobos and Deimos, do have odd shapes, but larger bodies like the nine planets and most of their moons do look like spheres.  That's because of the nature of gravity.  You can think of gravity as a force that points inward toward the center of the planet so that every part of the surface is pulled evenly toward the center, resulting in a spherical shape. \nOf course, planets are not perfect spheres because mountains and valleys and even skyscrapers are all deviations from the spherical shape.  However, as planets get larger, gravity gets stronger, until eventually large objects on the surface are crushed under their own weight.  That's why we don't have mountains that are 50 miles high or skyscrapers that are 2,000 stories tall.  Planets stay basically spherical because any large deviations get crushed. \n\nAlthough gravity keeps planets close to spherical, there are other forces that cause deviations from the basic spherical shape.  For example, the rotation of the earth once every 24 hours, causes an apparent centrifugal force which creates a bulge at the equator.  In fact the earth's diameter at the equator is 7,926 miles while the diameter between the poles is only 7,900.
862988
Earth and the other planets were formed from a giant cloud of gas and dust revolving around the primitive sun. As in any other moving fluid, local whirlpools kept appearing and disappearing all the time. \nAs the cloud started to cool, local perturbations caused density variations : some whirlpools got lumpier than others, just as in a bowl of porridge when it cools off. They thus grew more stable and accumulated more matter because of their increasing gravity. On further cooling, these separated out as planets, molten globes of matter still spinning furiously.\nEven when the planets solidified at last, they retained a part of their original spin. That's why the Earth and the other planets are still spinning around their axes. That's what, thankfully for us, creates days and nights.
353300
This question goes all the way back to the formation of the solar system.  Back then, when the Sun was a very young star, it was surrounded by what's known as an 'accretion disk'.  This disk was simply just a lot of gas and dust that never got sucked into the sun.  Eventually, particles started colliding with each other and they started to clump together.  Eventually the clumps started sticking to other clumps, so on and so forth.  However, there was a difference starting to show up.  The sun, being young as it was, was really hot, and it had pretty strong solar winds.  These winds were able to blow lower mass particles (like hydrogen and helium) out of the inner solar system.  So planets like the Earth and Mars were never able to collect these gases.  But out by, say, Jupiter, the winds had calmed down.  And it was a lot colder.  Cold enough, in fact, that water ice could form on the surface of the new planets.  This water ice added to the mass of the outer planets.  Once this ice was added, there was enough mass for the outer planets to incorporate hydrogen gas.  Hydrogen and helium are both incredibly light gases.  If a planet don't have a strong enough gravitational field, then it won't be able to hold on to the H and He.  With the ice and the cooler temperatures, this was able to happen.\n\nWow, I kind of rambled there, but I hope it helps!
1116621
Cigar Me was close when he mentioned firing the thrusters to maintain the satellite's orbit.  Satellites generally don't stay where we put them.  \n\nThe Earth's gravity is the most dominant force acting on a satellite.  Since the center of the Earth is stationary relative to the satellite, there is no net work done and force of gravity maintains a constant, never changing orbit.  However, there's a lot of other forces acting on satellites that cause their orbits to drift.  \n\nThe Earth bulges around the equator due to a soft molten layer and centripetal acceleration (the Earth spins like a centrifuge).  The extra mass around the equator changes the satellite's orbit over time (this can be a good thing - with a 98.6 degree angle between the satellite's orbit plane and the equatorial plane, the satellite's orbit plane rotates at the same rate that the Earth orbits the Sun.  In other words, you can set up an orbit where the satellite always crosses the equator in a northerly direction at sunrise and always crosses the equator in a southerly direction at sunset - or if you want pictures with no shadows, you can set up your orbit so it always crosses the equator in a northerly direction at noon.)\n\nThe atmosphere slowly tapers off the further away from Earth you get, so low altitude satellites still experience atmospheric drag.  They eventually fall back to Earth and usually (but not always) burn up during re-entry.  To keep a low altitude spacecraft, such as the International Space Station, in orbit, you have to periodically re-raise the orbit by firing the thrusters (this is why resuming space shuttle flights is so critical - the space shuttles, along with some Russian spacecraft, supply fuel for the thrusters to the ISS).\n\nHigh altitude satellites, such geosynchronous communications satellites, are beyond the furthest reaches of the atmosphere and will never fall back to Earth.  However, they, like all satellites, are still affected by the Sun's gravity and the Moon's gravity.  That pulls them out of their assigned orbits.  Once again, the thrusters are used to correct the satellite's orbit to keep it in its assigned position.
792195
Interesting question.  You can extend it - why does the Earth continue to turn on its axis?  And circle the sun?  Why does the sun circle the center of the galaxy?  Why do things keep going, year after year for billions and billions of years?\n\nNewton thought about this and came up with one of his famous laws:  Without an external force, a body in motion stays in motion, a body at rest stays at rest.\n\nThe second half is easy.  Put a rock on the floor and it will stay there forever until you pick it up.  It won't move without an external force.  So what if you shoot a bullet into the air.  We all know it falls back, but why?  Because the force of gravity acts on it.  Take away gravity and it will still stop.  Why?  Because the friction of air on the bullet's surface will slow it down and finally stop it.  Take away air, take away gravity, and the bullet will go on forever.\n\nSo to answer your question:  Simply put, the asteroids have no forces to stop them.  Gravity keeps them trapped around the sun, but they outside of the range where they fall in, so they simply continue to go around, just like the planets such as Earth.  The asteroids started in motion at the formation of the solar system 4.5 billion years ago, and except for random collisions that altered courses and accelerated (or decelerated) the rocks, no force has acted on them to slow them down.  A perfect example of Newton's law, even more amazing because Newton did not know of the existence of asteroids.
682353
It works like this...\n\nA satellite is launched into space at a very specific angle.  It is carried to a specific height and gravity keeps it where they want it the same way it keeps the moon in check.  The object is in a continuous state of free fall but it doesn't fall from the sky (OK, when they get the math wrong some do fall from the sky.) because of it's inertial mass.  The inertial mass (newtons 2nd law) causes the satellite to move away from the earth and out into space... the gravity of the earth keeps pulling it down so that it can't get away.   \n\nLemme see if I can clarify.  draw a circle, better yet, get an orange, apple, round object.  The satellite is a few hundred miles above the earth... now get a pencil, pen, ruler, whatever.  put the orange on a desk and hold the pencil over top of the orange earth.  make sure it is pointing side to side and not straight up above our earth.  This is the path of the satellite when there is no gravity, it wants to go in a straight line away from the planet... You can see that it would get further away from the surface the more it moves away from the center.\n___\n.O\n\nEarth's gravity pulls it back toward the earth, counteracting the satellites natural motion, and when all the math is figured out you can keep it at an exact height above the earth and if your really good you can make it geosynchronous (always over the same spot)
695854
To 'float' you don't need any forces.  To stay in an orbit you need the force of gravity.  All mass has gravity.  Where gravity comes from is difficult to say.  Physicists are grappling with string theory to describe this one.
284270
They are moving tangentially to their orbital path at a speed that doesn't change.  At the same time, the Sun warps space like a bowling ball on a stretched rubber sheet.  They keep trying to fall into the Sun but they move sideways just fast enough to keep missing it by the radius of their orbit.\n\nIn addition to warping space, the mass of the sun also slows down time, but that's another matter.