the length of a year was discovered in the 2nd century bc.
when was the length of a year discovered?
2nd century bc
bullet::::- equal temperament: during the han dynasty (202 bc–220 ad), the music theorist and mathematician jing fang (78–37 bc) extended the 12 tones found in the 2nd century bc "huainanzi" to 60. while generating his 60-divisional tuning, he discovered that 53 just fifths is approximate to 31 octaves, calculating the difference at formula_1; this was exactly the same value for 53 equal temperament calculated by the german mathematician nicholas mercator (c. 1620–1687) as 3/2, a value known as mercator's comma. the ming dynasty (1368–1644) music theorist zhu zaiyu (1536–1611) elaborated in three separate works beginning in 1584 the tuning system of equal temperament. in an unusual event in music theory's history, the flemish mathematician simon stevin (1548–1620) discovered the mathematical formula for equal temperament at roughly the same tim, yet he did not publish his work and it remained unknown until 1884 (whereas the "harmonie universelle" written in 1636 by marin mersenne is considered the first publication in europe outlining equal temperament); therefore, it is debatable who discovered equal temperament first, zhu or stevin. in order to obtain equal intervals, zhu divided the octave (each octave with a ratio of 1:2, which can also be expressed as 1:2) into twelve equal semitones while each length was divided by the 12th root of 2. he did not simply divide the string into twelve equal parts (i.e. 11/12, 10/12, 9/12, etc.) since this would give unequal temperament; instead, he altered the ratio of each semitone by an equal amount (i.e. 1:2 , 1:2, 1:2, etc.) and determined the exact length of the string by dividing it by (same as 2).
list of chinese discoveries
bullet::::- first exoplanet discovered beyond the “snow line”, by shannon hall on july 22, 2014, universe today





























bullet::::- transiting exoplanet with longest known year discovered by kepler mission, july 22, 2014, redorbit





























bullet::::- discovery of a transiting planet near the snow-line, david m. kipping, guillermo torres, lars a. buchhave, scott j. kenyon, christopher e. henze, howard isaacson, rea kolbl, geoff w. marcy, stephen t. bryson, keivan g. stassun, fabienne a. bastien, (submitted on 17 jul 2014)
kepler-421b