Latitude constant latitude and constant longitude, which are constructed with reference to the rotation axis of the Earth. The primary reference points are the poles where the axis of rotation of the Earth intersects the reference surface. Planes which contain the rotation axis intersect the surface at the meridians; and the angle between any one meridian plane and that through Greenwich (the Prime Meridian) defines the longitude: meridians are lines of constant longitude. The plane through the centre of the Earth and perpendicular to the rotation axis intersects the surface at a great circle called the Equator. Planes parallel to the
What on Earth June 1975 and from May to August 1977. What on Earth What on Earth is a Canadian television panel game show and discussion program which aired on CBC Television from 1971 to 1975. It was based on the 1959 CBC game show "Who Knows?" The series featured items from the Royal Ontario Museum, the Ontario Science Centre and other facilities. These were brought before a panel who attempted to identify the objects. After the object's identity was guessed or revealed, it was the subject of further conversation by participants. This half-hour series was broadcast as follows (times in Eastern): Episodes