arcsekunder

Arcsekunder is a unit of angular measurement. It is equal to 1/3600 of a degree. The term "arcsecond" comes from the Latin words "arcus" meaning arc and "secundus" meaning second. It is a subdivision of the arcminute, which is itself a subdivision of the degree. Therefore, one degree contains 60 arcminutes, and one arcminute contains 60 arcseconds. This means one degree is equivalent to 3600 arcseconds. The symbol for arcsecond is a double prime ("). For example, 1" represents one arcsecond.

Arcseconds are commonly used in astronomy to measure the apparent size of celestial objects or the angular separation between them. Due to the vast distances involved in space, angular measurements are often very small, making arcseconds a necessary unit for precision. For instance, the angular diameter of the Moon as seen from Earth is approximately 1800 arcseconds. Similarly, the resolution of telescopes is often described in arcseconds, indicating the smallest angular detail they can discern. In cartography and surveying, arcseconds can also be used for very precise measurements of angles and positions.