A minute of arc, arcminute, or minute arc (MOA), is a unit of angular measurement equal to one sixtieth (1⁄60) of one degree (circle⁄21,600), or (π⁄10,800) radians. In turn, a second of arc or arcsecond is one sixtieth (1⁄60) of one minute of arc. Since one degree is defined as one three hundred and sixtieth (1⁄360) of a rotation, one minute of arc is 1⁄21,600 of a rotation. It is used in those fields which require a unit for the expression of small angles, such as astronomy, optometry, ophthalmology, optics, navigation and marksmanship.
The number of square arcminutes in a complete sphere is
or approximately 148,510,660.498 square arcminutes.
The arcsecond is 1⁄3,600 of a degree, or 1⁄1,296,000 of a circle, or (π⁄648,000) radians, which is approximately 1⁄206,265 radian.
To express even smaller angles, standard SI prefixes can be employed; in particular, the milliarcsecond, abbreviated mas, is used in astronomy.
Read more about Minute Of Arc: Symbols and Abbreviations
Famous quotes containing the words minute and/or arc:
“At each minute we are crushed by the idea and the feeling of time. And there are only two ways to escape this nightmare, Mto forget it: pleasure and work. Pleasure wears us out. Work fortifies us. Let’s choose.”
—Charles Baudelaire (1821–1867)
“If I am not, may God put me there; and if I am, may God so keep me.”
—Joan Of Arc (c.1412–1431)