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Mar 30


March 30, 2022 @ 7:00 PM - 9:00 PM EDT

|Recurring Event (See all)

An event every week that begins at 7:00 PM on Wednesday, repeating until May 18, 2022


Register below!

Wednesdays, 7 PM.  March 30; April 6, 13; May 4, 11, 18

The measurements of time in hours, days, months, and years has astronomy roots. Historically, calendar dates were particularly complex to fix in all cultures because the Earth, moon, and sun have revolution rates that are not simple multiples. Objects in the sky and in space are assigned coordinates using different systems. These coordinates are vital to determining and specifying the motions and orbits of space objects. It takes six parameters to specify an orbit. We explore these themes.

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.


March 30, 2022
7:00 PM - 9:00 PM
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