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 of, arc and/or minute:

“Well, there’s no one at all, they do be saying, but is deserving of some punishment from the very *minute of* his birth.”

—Augusta, Lady Gregory (1859–1932)

“Male urination really is a kind of accomplishment, an *arc* of transcendance. A woman merely waters the ground she stands on.”

—Camille Paglia (b. 1947)

“Every day, in this mostly male world, you have to figure out, “Do I get this by charming somebody? By being strong? Or by totally allowing my aggression out?” You’ve got to risk failure. The *minute* you want to keep power—you’ve become subservient, somebody who does work you don’t believe in.”

—Paula Weinstein (b. 1945)