Degree to Sign

The Babylonians used base-60 arithmetic and noticed the year was close to 360 days — convenient because 360 divides evenly by 2, 3, 4, 5, 6, 8, 9, 10, 12, 15, 18, 20, and more. That ridiculous number of factors makes slicing a circle into halves, thirds, quarters, fifths, sixths, and eighths all come out to whole numbers. A base-100 system would only divide cleanly by 2, 4, 5, 10, 20, 25, and 50 — far less flexible for geometry and land surveying.

Navigation requires quick mental arithmetic with headings, bearings, and wind corrections. "Turn right to heading 270" is instantly understood in a cockpit; "turn right to 4.712 radians" would get someone killed. Compass roses, runway numbers (which are headings divided by 10), and nautical charts all assume a 360° circle. The entire global aviation and maritime infrastructure — from VOR stations to AIS transponders — is calibrated in degrees.

The degree symbol is a small raised circle placed immediately after the number with no space (45°, not 45 °). On Windows, hold Alt and type 0176 on the numpad. On Mac, press Option+Shift+8. On phones, long-press the zero key. In HTML, use ° or °. A common mistake is using a superscript letter "o" or the ring-above diacritic — these look similar but are different Unicode characters and can break search or data parsing.

One degree equals 60 arcminutes, and one arcminute equals 60 arcseconds — so 1° = 3,600″. To convert DMS to decimal, divide minutes by 60 and seconds by 3,600, then add them to the degree value. For example, 40°26′46″N becomes 40 + 26/60 + 46/3600 = 40.4461°. Google Maps uses decimal degrees internally but lets you enter either format. At the equator, one degree of longitude spans about 111 km.

Yes — the French Revolutionary government introduced the gradian (grad), dividing a circle into 400 parts to match the metric system. A right angle became exactly 100 grad. They also tried decimal time (10-hour days) and a decimal calendar. The time and calendar experiments died within a few years, but gradians survived and are still used in French and German surveying. Every scientific calculator has a GRAD mode because of this 230-year-old French experiment.

Twelve comes from dividing the roughly 360-day year by the roughly 30-day lunar month — giving about 12 lunations per year. Babylonian astronomers around 500 BCE formalised this by splitting the ecliptic (the Sun's apparent path) into twelve 30° segments, each named after a prominent constellation in that sector. Twelve also divides evenly by 2, 3, 4, and 6, making it convenient for calendrical and astrological calculations. The choice was part astronomical observation, part mathematical convenience.

No, and they haven't for about 2,000 years. Earth's axial precession (a slow wobble completing one cycle every 26,000 years) has shifted the equinoxes by roughly one full sign since the Babylonians fixed the system. The Sun enters the constellation Pisces around March 12, but the astrological sign of Aries begins on March 21. Western astrology uses "tropical" signs fixed to the equinoxes, while Vedic (Hindu) astrology uses "sidereal" signs that track the actual star positions — creating a ~24° discrepancy between them.

The ecliptic actually passes through 13 constellations, not 12. Ophiuchus (the Serpent Bearer) sits between Scorpio and Sagittarius, and the Sun spends about 18 days in it each November/December. NASA pointed this out in 2016 (while emphasising they do astronomy, not astrology), and it briefly went viral. Astrologers were unimpressed — the zodiac signs are 30° mathematical divisions of the ecliptic, not the constellations themselves. Adding Ophiuchus would break the entire 12-based system.

Ancient and medieval navigators used the zodiac as a celestial calendar and clock. Knowing which sign the Sun occupied told them the season and approximate date, which determined which stars would be visible at night for navigation. The ecliptic's angle relative to the horizon changes predictably through the signs, helping estimate latitude. Arab navigators used zodiac-based star tables (zij) for open-ocean sailing centuries before the sextant existed. The zodiac was a practical tool long before it became a personality quiz.

Because the signs are mathematical constructs, not astronomical ones. The Babylonians deliberately chose equal 30° slices for computational simplicity — dividing the year into twelve identical months of sky. The actual constellations vary wildly in size: Virgo spans about 44° of the ecliptic while Scorpius covers only about 7°. Forcing them into equal boxes was a conscious simplification that made planetary position calculations possible with ancient arithmetic. Precision was less important than predictability.