Arc Second (″)
The arc second, symbol ″, is equal to 1/60 of an arc minute or 1/3,600 of a degree, so there are 3,600 arc seconds in one degree and 1,296,000 arc seconds in a full circle. Like the arc minute, it has deep roots in Babylonian astronomy and has remained vital for precision measurement. Arc seconds are heavily used in astronomy to describe angular distances between stars or the apparent size of celestial objects. In geodesy and cartography, arc seconds are used to define coordinates with extreme accuracy. Modern telescopes and space missions often measure distances in arc seconds, reflecting the importance of this unit in advancing scientific discovery.
Degree (°)
The degree, symbol °, is one of the oldest units of angle measurement, with origins in ancient Babylonian astronomy dating back to around 3000 BCE. The Babylonians used a base-60 (sexagesimal) number system, which is why a full circle was divided into 360 degrees; in contrast, a full circle is 2π radians. This division allowed for convenient fractions and calculations. Degrees became the standard in Greek, Arabic, and later European science, eventually spreading globally. Although radians are preferred in higher mathematics due to their direct relationship to circle geometry, degrees remain dominant in navigation, cartography, geometry education, and everyday contexts, making them one of the most recognizable and widely used angle units in history.