Sphere

Sphere Facts

Notice these interesting things:

• It is perfectly symmetrical
• All points on the surface are the same distance r from the center
• It has no edges or vertices (corners)
• It has one surface (not a "face" as it isn't flat)
• It is not a polyhedron

Glass Sphere.
Balls and marbles are shaped like spheres.

You can spin or drag this sphere:

Largest Volume for Smallest Surface

Among all 3D shapes, the sphere encloses the most volume for the least surface area.

Example: if you blow up a balloon it naturally forms a sphere because it is trying to hold as much air as possible with as small a surface as possible. Press the Play button to see.

In Nature

The sphere appears in nature when a surface wants to be as small as possible. Examples include bubbles and water drops. Can you think of more?

Volume and Surface Area

Surface Area = 4 × π × r²

Volume = (4/3) × π × r³

Try dragging point "A":

Also see Volume and Area of a Sphere Calculator

Spheroid

The Earth

The Planet Earth, our home, is nearly a sphere, except that it is squashed a little at the poles:

it is technically a spheroid,
but a very mild version of one.

Here is a more extreme spheroid:

Hemisphere

A hemisphere is an exact half of a sphere.

Other Cool Spheres