A spherical angle is a particular dihedral angle; it is the angle between two intersecting arcs of great circles on a sphere. It is measured by the angle between the planes containing the arcs (which naturally also contain the centre of the sphere).[1]
Historically
Spherical angle also has an overall formula on M.Kemal Atatürk's book Geometri[2] in 1936, he used older formulas and techniques to clarify this measurements to make a very ahead of time popular science program for Turkish public education system.
Considering an object needed 6 overall straight faces or 3 dimensions to draw a whole object as it is, he formulated that object to be seen by each dimension so to say we are able to draw it in two dimensions to get a 3rd dimensional image as round has 360 degrees in its angles multiplying a round to its own, giving √ 129600 = 360 or 360*360=129600 as simply. His book Geometri also defines angles can be expanded to infinite when needed for measurements, this methodology for sphere's angles also allowing us to coordinate around a globe for navigation purposes for example and replaces function of coordinates when needed.