GEK1506 Heavenly Mathematics & Cultural Astronomy, Tutorial 9, Solutions

  1. 18+19=37 and there are 30 days in September, so you would guess October 7. It you follow the detailed rules explained in my paper, it turns out that it is actually October 6, but the rule of thumb is still accurate to one day.
  2. Errors are more noticeable in a lunar or lunisolar calendar than in a solar calendar. The emperor claimed to be the son of Heaven.
  3. At the time of sunset they consider the altitude of the Moon, the elongation between the Sun and the Moon at sunset and the age of the Moon.
  4. In November the equation of time is positive, so the true Sun will be ahead of the mean Sun.
  5. In Beijing the earliest sunrise will be before the June solstice, while the latest sunset will be after the June solstice. The latest sunrise will be after the December solstice and the earliest sunset will be before the December solstice.
  6. Please see Which Day Does the Sun Rise Earliest in Singapore?

Helmer Aslaksen
Department of Mathematics
National University of Singapore