How to Make a Sphere in SketchUp

1. 
   1
   Download Google Sketchup. You can find more instructions about Google Sketchup here .
2. 
   2
   Make a circle (the size you want the sphere to be) in one axis.
3. 
   3
   Make another circle bigger than the first one, on a different axis, but the middle of this should be the middle of the first one. You might have to make the bigger circle on the blue axis much higher than the smaller one and then use the move tool to bring to to the middle.
4. 
   4
   Select the bigger circle, make sure nothing else is selected.
5. 
   5
   Click the follow me tool, and click the small circle once.
6. 
   6
   Erase the extra.(the big circle)

Method2

EditStarting With a Square

1. 
   1
   This method takes a little longer but will give you a different surface dynamic.Method 1 is recommended however for flawless spheres.
2. 
   2
   Open SketchUp and create a square that is 20' x 20'.
3. 
   3
   Using the pencil tool cut the square into 4 equal parts.
4. 
   4
   Create a circle inside the square starting at the dead center. Set the diameter to 10' (touching the sides of the square).
5. 
   5
   Delete one of the bisecting lines inside of the circle.
6. 
   6
   Replace the deleted line with a line created by the arc tool. Rotate your view so the arc goes straight up with a diameter of 10'
7. 
   7
   Create an identical arc on the underside of the figure.
8. 
   8
   Delete all remaining sections of the square leaving the circles intact.
9. 
   9
   Delete one half of the original circle and the inside surface of the circle created by your two arcs.
10. 
    10
    Use the follow tool to drag the remaining half circle all the way around the two arcs and then delete or hide any lines from the surface.