A turn is 360°. As an angular unit it is mainly useful for large angles, such as in connection with coils and rotating objects. See also winding number. The British astronomer and science writer Sir Fred Hoyle (1915 - 2001) in Astronomy (London 1962), proposed dividing the circle, or turn into 1000 milliturns. with each milliturn corresponding to an angle of 21' 36", or less than half a degree.