The Relative Timing Between Solar and Lunar Eclipses

-- | January 1, 2016

Question: I’m working on a thesis for the chronology of the last month of Jesus life. According to NASA, as best I can make out, there was a partial Lunar Eclipse about sunset 6-7PM in Israel the day Jesus died, April 3, AD 33.  Also they record a total Solar Eclipse 2 weeks earlier about 1pm? March 19 AD 33 (I don’t think this event was observable from Israel).  My problem is if my understanding of NASA’S astronomical charts is correct there is a span of 15 and 1 quarter days between the 2 events but if half a Lunar Month (29.5 days) is 14 and 3 quarter days, how is it that there is a half a day difference?  I’m an unemployed carpenter not an informed astronomer. On my own I can’t work out the maths or fully comprehend the NASA charts.  Can you please confirm the exact time of the conjunction March 19 AD 33 in what would be Jerusalem time and how the intervening span is what it is, if it is not 14 and 3 quarter days?  — Glen

Answer: The NASA lunar eclipse information indicates that a partial lunar eclipse occurred on April 3, 33 CE with peak totality happening at about 16:47:51 local time in Jerusalem (14:47:51 UT).  NASA’s solar eclipse tables also indicate that there was a total solar eclipse on March 19, 33 CE with peak totality at about 12:50:14 local time in Jerusalem (10:50:14 UT), though it was not visible from Jerusalem.  The difference between these solar and lunar eclipses is about 15 days and 4 hours.  I believe that the reason why this time difference is not exactly one half of one synodic month (29.53 days) is due to the subtle differences between the lunar and solar orbits which dictate the periodicity of eclipses.  This periodicity, called the Saros cycle, has been known since ancient times and occurs due to the natural resonances between the synodic month, the time between orbital perigees, and time between orbital node crossings.  NASA’s “eclipses and the Saros” page contains all of the details regarding this recurrence for eclipses.

Jeff Mangum