Wednesday, August 29, 2012

The Step Dial of Ahaz: Understanding Hezekiah's sign







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Though we know little about the dial of Ahaz other than its role in Hezekiah’s miraculous sign, we can make some very useful guesses as to its design with regard to knowing the duration of the shadow of the sun going back 10 steps. For instance, we can know for certain Ahaz’ dial must have had a minimum of 10 steps per six hours (if and only if the event began at noon). This would allow Hezekiah the choice of the shadow going forward or backward 10 steps.



However, the Jews kept time in hours. The exact era this observance began may not be known, but the Egyptians also had this practice by at least 300 years prior to Hezekiah’s miracle. We can at least be sure Ahaz’ dial was not in increments of one step per hour. Two or three steps per hour would be sufficient, and four steps per hour could be argued. Designs of 5 steps per hour or more would present too much visual detail or clutter to be very practical. In fact, even four steps an hour, presenting our familiar 15, 30, 45 and 60 minute intervals, would offer little added practical value in a culture devoid of wrist watches, automobiles, telephones and other conveniences of technology. Court messages were most likely sent by a runner and other business would hardly require any better discipline than could be accomplished within intervals of 20, 40 and 60 minutes.



By science we can also know that increments of two or four steps per hour are not viable. The famous trio of lunar eclipses undergirding Ptolemy’s Canon seem precisely on schedule in 720 and 721 BC. Though they actually occurred 18 years earlier, a sun dial design of two or four steps per hour would have thrown these lunar eclipses off schedule contrary to modern calculations.




Even with a design of three steps per hour, there is some room for discussion. Hezekiah had the choice of the shadow going forward or back 10 steps. The tenth step, inclusive of the top (sunrise) step would be 9 a.m. Inclusive of the 9 a.m. step, 10 steps would carry us forward to a vertical (noon) shadow. The bottom would be counted as a step by this reckoning. But such a scenario would require that Isaiah approached Hezekiah with such a proposal perhaps minutes before 9 a.m. This presented the option of the sun going forward 10 steps. When Hezekiah opted for 10 steps backward, the shadow continued forward past the 9 a.m. step as God decelerated the earth’s rotation — we assume the shadow never reached the 9:20 a.m. step, but as rotation slowed as much as 20-30 minutes elapsed before rotation changed directions. There is no reason the shadow could not have crossed the 9:20 threshold if we also assume normal rotation resumed before the sunrise step. A similar period of deceleration would be in order at the end of the backward movement of the sun’s shadow. Since there are no secular accounts of a double sunrise in known Near East history, we might prefer to believe the shadow went past the 9:20 mark before reversing. A mid morning event seems to allow the simplest reading in which the shadow could continue forward (down) or go backward in contrast to a late morning or midday timetable. Moreover, scripture says the shadow went back the ten steps it had gone down — not nine, not eleven.



This reconstruction, though hypothetical, seems to be required by the science of eclipses in the sense that the shadow would have gone backward about 3 hours 20 minutes, and more importantly returned to its original position in about 7 hours 40 minutes. Some have claimed disastrous consequences from reverse rotation. Not so. Tides are merely caused by land masses rotating into bulges in the oceans. Direction of rotation does not matter. The earth’s fluid core did slosh about somewhat, as evidenced by comparing NASA solar eclipse data with a witnessed Assyrian eclipse (781 BC). At Hezekiah’s sign, the earth’s wobble changed (or began), so NASA’s predicted latitude of greatest eclipse is off perhaps 1° south for solar eclipses prior to 713 BC. Obviously, east-west location (longitude) also requires a 115° shift for the solar eclipse noted here.



Posted by HJK at 7:52 PM



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