A minute of arc [See Link] or arcminute (MOA) is a unit of angular measurement, equal to one sixtieth (1/60) of one degree. Since one degree is defined as one three hundred sixtieth (1/360) of a circle, 1 minute of arc is 1/21,600 of the amount of arc in a closed circle.
There are 148,510,800 square arcminutes in a complete sphere.
A circle is 360 degrees.
A degree is a circle divided into 60 equal parts.
An arcsec is a degree divided into 60 equal parts.