Normal Section of an Ellipsoid
• The gray plane is tangent to the ellipsoid at A.
• The normal NA at A is orthogonal to the tangent plane.
• The red plane, containing NA is the normal plane at A.
• The curve from A to B, the intersection of the ellipsoidal surface and the the normal plane, is called the normal section.
• The normals at A & B are generally not coplanar.
• Construction of a normal plane at B which passes through A will generate a different normal section.
• Normal planes may not contain the origin.