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, minute and/or arc:
“I make this in a warring absence when
Each ancient, stone-necked minute of love’s season
Harbours my anchored tongue....”
—Dylan Thomas (1914–1953)
“You don’t want a general houseworker, do you? Or a traveling companion, quiet, refined, speaks fluent French entirely in the present tense? Or an assistant billiard-maker? Or a private librarian? Or a lady car-washer? Because if you do, I should appreciate your giving me a trial at the job. Any minute now, I am going to become one of the Great Unemployed. I am about to leave literature flat on its face. I don’t want to review books any more. It cuts in too much on my reading.”
—Dorothy Parker (1893–1967)
“If I am not, may God put me there; and if I am, may God so keep me.”
—Joan Of Arc (c.1412–1431)