Circle of a sphere the Equator the only great circle. By contrast, all meridians of longitude, paired with their opposite meridian in the other hemisphere, form great circles. The diameter of the sphere which passes through the center of the circle is called its axis and the endpoints of this diameter are called its poles. A circle of a sphere can also be defined as the set of points at a given angular distance from a given pole. When the intersection of a sphere and a plane is not empty or a single point, it is a circle. This can be seen as follows:
Science On a Sphere This work enabled MacDonald's invention to move out from the laboratory and into performance spaces. A patent was awarded to NOAA for Science On a Sphere in August 2005, with MacDonald credited as the inventor. General system architecture and configuration specifications are as follows. The carbon fiber sphere is in diameter. Other sphere sizes are possible, such as 48" and 60". Larger sizes are possible too. The 68" sphere with a single seam at the equator weighs under . The sphere is attached to the ceiling or suspension structure with a three-point suspension system to hold the sphere in place