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Member Reports from James Q. Jacobs

Feb 16

2011

Epoch Calc update online

James Q. Jacobs

An Epoch Calc updated version is now online. Most recently, all constants were integrated into a singular, sidereal-based set derived entirely from orbital constants. The formulations of all derived variables is now displayed and the AeGeo code is expanded. The date setting now includes months and days, and conversion to Julian date and between Julian and Gregorian calendars is automatic (the latest version of Excel is needed to support its floor.absolute function). Epoch Calc v2011 = epoch_calc_v2011.xls, an Excel applet. Calculate temporal variation in astronomic constants, obliquity of the ecliptic, eclipses, and more. Some intro here: Eclipse Calc , an... Read More...

Nov 25

2010

Watching Eclipses, Counting Orbits

James Q. Jacobs

The telescope is no substitute for counting and thinking. Ancient people, before telescopes, could have determined basic astronomy constants by counting and thinking. During a Metonic eclipse period, rotation observations enable solving period proportions as follows: 235 moons = 6,958.6877 rotations 254 lunar orbits = 6,958.7014 rotations 235 : 6,958.6877 = 235.00046 : 6,958.7014 254 lunar orbits = 235.00046 moons Subtraction solves solar orbits 254.0 - 235.00046 = 18.99954 solar orbits Division solves rotations per orbit 254 lunar orbits = 6958.70257 rotations 6958.70257 / 18.9995407 = 366.25636 rotations per orbit Download the PowerPoint: http://jqjacobs.net/astro/ppt/counting_moons.ppt Read more about fundamental and ancient... Read More...

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