The meridians are maximum imaginary semicircles drawn from the North Pole to the South Pole. They measure [?] degrees.

The reference meridian (0 degrees) is the [?], a name that comes from an astrological observatory located near _______(London).

CHARACTERISTICS:
The number of meridians is [?].

Their [?] is N-S.

Their point of maximum separation at the [?] and they converge at the poles.

They divide parallels in [?] angles.

The arch of the parallels has a value of [?] degrees.