A circle chart. Click to expand.
The firts is to create a circular frame that outlines all vertices with the largest circle (see example). After that is complete, you simply fill in the excess area with circles on scale with the layer that it is on.
The second way is simpler, but generally less aesthetically pleasing. To do this, you simply create the smallest circle in the guide, and slowly build larger circles on top of it until you reach the circle you want as your middle point. You then start building juicier circles on top of your sphere until you reach the smallest circle again.
There are multiple guides to make circles on Youtube, and you can also find several on the Minecraft Forums and by simply searching Google, or any other search engine.
A circle is the same as 000°. You can divide a circle into smaller portions. A part of a circle is called an arc and an arc is named according to its angle.
A circle graph, or a pie chart, is used to visualize information and data. A circle graph is usually used to easily show the results of an investigation in a proportional manner. The arcs of a circle graph are proportional to how many percent of population gave a certain answer.
A medium size created from increasingly small circles.