Wednesdays, 7 PM. March 30; April 6, 13; May 4, 11, 18
March 30- Measuring time
Solar vs. sidereal day. Defining 1 second. Modern timekeeping. Leap seconds. Time zones. Sundials, analemma
April 6- Calendars and Lunar Orbit Details
Constraints of rotation and revolution. Solar, sidereal, lunar, lunisolar calendars. Ancient Roman, Julian, Gregorian calendars. Rules for leap years. Passover and Easter. Julian Dates. Review of moon phases essential to .lunar calendars. Jewish, Muslim, Chinese, Mayan calendars. Non-astronomical calendars
Lunar orbit details. Moon’s inclination, distances. Total eclipses. Eccentricity, supermoons. Tidal locking. Libration. Standstills. Nutation. Precession of lunar nodes
April 13 & May 4- Coordinate systems
Local coordinates: altitude, azimuth. Review of latitude & longitude on Earth. Celestial coordinates: declination, right ascension. Algorithms for converting, ALTI/AZIMUTH ––>DEC/RA. Many variables, spherical trigonometry, exact UTC time.
Correcting for precession, by 50-year EPOCHS in star maps, by hourly computer updates in professional telescopes.
2-D map issues, sky projections. Worksheet practice. Ecliptic and Galactic coordinates.
May 11- Mapping the heavens
Review of celestial sphere and constellations. 88 official list, hundreds of asterisms. Rey diagrams. Circumpolar and Zodiac constellations. Major Northern Hemisphere constellations by season. Usefulness for mapping, locating objects, star guides.
Naming stars: proper, Bayer, Flamsteed. Star maps, star globes, star catalogs. Samples of the endless myths about constellations. Samples of endless poetry and literary references. Messier objects, Messier marathon
May 18- Orbital parameters
Kepler’s laws. Ellipses. The six key orbital parameters. What must be measured to define an orbit, and how frequently? Newton’s geometric procedures. Liebnizt and Euler procedures. Modern procedures- “MIT telegram”, high speed computers. Technical printout of parameters. Converting back to DEC/RA and Alti/Azimuth coordinates. It’s all heavy math and software.
INSTRUCTOR- David Kiefer. Professor of astronomy, CUNY colleges. Instructor in AAA classes and chairman of the Classes Committee.
