How can I make a model of the celestial sphere?
370674
Why not just buy one?  Go to your hobby store.  If you insist on making something, make cookies.
985957
I did a model of Mars once using a very large popcorn bowl and papier maiche.  No idea how to spell that, but any craft store will have it.  It made a nice hemisphere.  It's be pretty easy to stick toothpicks in the wet stuff as foundations and then use foil or something around it...\n\nWe also threw small rocks at the wet plaster to make craters....
350944
This sounds like a homework question?  Maybe I shouldn't give you the whole answer, so you can learn something on your own.\n\nYou are describing a Cassegrain telescope.  You can use the mirror formula to calculate the image plane for the first optic (the concave mirror) and then use that as the object plane for the second optic (the convex mirror) to get your final focal image plane.\n\nMirror Equation:  (1/So) + (1/Si) = -2/R\n\nSo = object plane (distance from object to mirror)\nSi = image plane (distance from image to mirror)\nR  = radius of curvature of mirror\n\nThe hardest part of these calculations is to use the right sign convention and to remember that the stars (initial object plane) can be treated as at infinity.
296979
The Moon is self explanatory, just look skyward at a full Moon to see it is spherical. The Earth takes some proving, but all you need is a space photo or two for people to get the idea. Oh, and the Earth is technically an oblate spheroid.
978352
A model volcano is always a hit. Or a model of the solar system. For the latter, just string some colored balls on the interior of a shoe box painted black. Pretty simple.
868699
Check at a site called neo (near earth objects)!!
385894
thats a circle not a sphere.\nYou can't make a sphere out of paper because its too curved.\n\nSee this link it gives you a good explanation why its so hard and some addition links to how to consruct a sphere in other ways
1071951
NASA/JPL lists a detailed ephemeris for this object with celestial coordinates ==> http://neo.jpl.nasa.gov/cgi-bin/db_shm?sstr=2004%20XP14
627250
All the solar system models you can buy are not to scale, which is OK if all you want to do is show the planets in the right order. But I much prefer a scale model. Only trouble is, it is WAY to big to make indoors. Jupiter is 10 times bigger than Earth and the Sun is 10 times bigger than Jupiter, so if Earth is a 1 inch ball, you need a 10 inch ball to be Jupiter (a basketball is 10 inches) and a 100 inch ball (8 feet 4 inch) for the Sun. Maybe a weather balloon would do. What I did instead was say that the basketball was the Sun, a one inch ball was Jupiter and a 1/10 inch pinhead was Earth. The other planet sizes can be calculated with the first link in the sources below. If the Sun is 10 inches, then Mercury is 34 feet away, Earth is 89 feet away and Pluto is about 2/3 of a mile away. What I did was take the class for a walk outside. We walked 2/3 of a mile from the school, setting up planets as we went. Or you could just set them in a row on the table and have the correct distances written on an information sheet. The whole point is that the planets are really small and really far apart. The models where the sun is only twice as big as Earth just are not convincing.
820745
Build an abacus.  \nArrange 10 beads on a piece of piano wire.  Every fifth bead should be a different collor.\n--oo--oo0-oooo0--\nMake a few more strings and mount them together in parallel or inline with each other.\n------ooooxoooox\nooo----oxoooox--\n--ooooxoo----ooo\n\nA really cool math based model would be a display of geometric shapes.\n\nYou could go to the matherworld site and print out some patterns for the platonic solids.  Then cut them out and fold them together.  The collection can be displayed in a couple of ways.  The easiest would be to mount them on straws poking out from a block of styrofoam.  The most dramatic would be to arrange them to hang in a mobile.  If you want instructions on making a mobile, send an email to samphelps at yahoo.\n\nPlatonic solids are the 3 dimensional shapes where all the sides are the same.  The most familiar is a cube where each side is a square.  Another is the tetrahedron where each side is a triangle.
102944
I think these answers are skating around what you really want. First, I don't think you mean stretch, so that it fits any shape.\n\nYou mean to 'unfold' the sphere after cutting it. Your mental imagry is a good way to see how the area of a sphere is calculated, but we wouldn't do it in a physical form since the sphere would not flatten nicely. So those who argue that it can't be done are missing the real advantage of what this question gets at. At least in my mind.\n\n\nAfter much messing around with this, the shape, after all the unfolding, is similar to two parabolas joined together.\n\nThe problem is that because the parabola like shapes don't quite make a parabola, the formulas don't quite work out. The area of a sphere is 4*pi*r^2.\n\nIf we consider them parabolas each has area (2*(pi*r)^2)/3 making the whole shape area (4*(pi*r)^2)/3. Of course this doesn't quite equal 4*pi*r^2.  Pi is roughly 3.14 and the denominator is 3. If they were to cancel in the equation, it would be correct.\n\nBecause the shapes are close, but not actual parabolas, finding the area will require calculus in order to establish that it equals 4*pi*r^2.\n\nIronically, you could use the ancient method of exhaustion to arrive at the area. I think Archimedes did this, but the method was developed by a man with your name :).\n\nHey, being a math major is useful after all.
1166430
Make a Dodecahedron. That's what I did.
1136054
Volcano is the classic answer.  Make a volcano out of clay and add some baking soda, vinegar, and red food coloring for the eruption.  You could use styrofoam balls from walmart or a craft store along with doll rods or straws to make a model of the solar system or an atom.  The links below are to some websites that have samples of some projects you could do.  If you tell me a little more specifically what kind of project you want, I could help more.
686518
http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/970314b2.html
137156
Well it depends on how old they are. I would get a big ball of plasticine. I would make it big and round, and then show them how it started out spinning. Then as it spun, it spread out like a plate. Take a lump and roll it for the sun, and smash the rest flat so it is a big flat plate. Cut out a hole in the middle and place the sun in it. Then get a knife an cut it into annuli, and then roll those annuli into balls, and place them at different distances from the "sun" ball. There, you have made yourself a big spinning solar system with a sun and planets. \n\nAnd you have had fun rolling the plasticine into balls and smashing it and cutting it etc.
175371
I would suggest purchasing this fine model listed in the below source, if you have the money to do so (the painted plastic one, first one listed).  It is a bit expensive, but it is really the best I know of since it actually shows all the atoms and is quite accurate.  It comes with instructions and even tells you how to paint it.  I actually teach with this exact model.  If you don't have money to purchase that model, it is possible to make it yourself using your own materials, but I would use the photos of this model as a guide to how to go about doing it.  It really depends on what you need it for and how detailed you need it to be.
667922
Either use volumes of revolution or compare cross sections of the sphere and a cylinder with a couple of cones removed. The latter is how Archimedes did it.