The Sundial of Ahaz


The Sundial of King Ahaz
by Anthony Lias

In 1985, Professor Kamal Salibi, of the American University of Beirut, wrote a brilliant book entitled The Bible Came from Arabia. Having had unexpected access to a gazetteer of Saudi Arabia published at Riyadh in 1977, his study of it confirmed him in the belief that the place-names of the Hebrew Bible – the actual location of which has always troubled Biblical scholars if taken to apply to what we now call Palestine – fitted perfectly if applied to the region called Asir, situated in West Arabia abutting on the Red Sea.
As someone who has a working knowledge of the original Hebrew vocabulary of the Bible, and who has published three books on place-names myself, I found the hundreds of examples listed by Professor Salibi absolutely convincing. However, I have recently found what I regard as a further powerful proof that Professor Salibi’s argument is correct. To explain why, I must point out that Asir lies (and lay) well within the tropic zone (between 17 and 19 degrees north of the Equator).
Now according to Isaiah 38:7,8, the prophet Isaiah (early eighth century BC) tells King Hezekiah in Jerusalem that ‘the Lord’ will give him a ‘sign’, namely this: “I will bring again the shadow of the degrees, which is gone down in the sun dial of [your father, King] Ahaz, ten degrees backward. So the sun returned ten degrees, by which degrees it was gone down.”
This retrograde motion of a shadow cast by a gnomon (i.e., a sundial pointer) has traditionally been regarded as a ‘miracle’, because at the latitude of the present-day Jerusalem (31 degrees 47 minutes north of the Equator), such a motion would be impossible. However, and I quote a respected figure, the English mathematician/astronomer Thomas Keith (1759-1824): “If a horizontal dial, which shows the hour by the top of the perpendicular gnomon, be made for a place in the torrid zone [i.e. the tropics], whenever the sun’s declination exceeds the latitude of the place, the shadow of the gnomon will go back twice in the day, once in the forenoon and once in the afternoon, and the greater the difference between the latitude and the sun’s declination is, the farther the shadow will go back.” Thomas Keith, A New Treatise On The Use Of The Globes. Revised Edition. London, 1855, pp. 336-7.
Now according to Professor Salibi, the original Jerusalem of Isaiah’s time will not have been in today’s Palestine, but in Asir, and within the torrid zone. Therefore the retrograde shadow on the ‘dial of Ahaz’ will not have been a ‘miracle’, but a fact. And no doubt an experiment could be set up in Asir at the present time to prove this. (N.B: since declination is the angular distance north or south of any heavenly body from the celestial equator, and since the highest possible declination of the sun is 23 degrees 28 minutes, it is plain that during certain months of the year the shadow will go back for every location within Asir.) It is possible that Professor Salibi is unaware of these astronomical details, which I believe are a vindication of his thesis.
The story about the odd behaviour of the sundial of King Ahaz also occurs in 2 Kings, 20:8-12. Here, the story makes it obvious that Isaiah knew that the “shadow of the degrees” on the sundial would go back, and that King Hezekiah did not. My theory is that Isaiah (who is thought by some Biblical scholars to have acquired some astronomical knowledge from the Assyrians), duped Hezekiah into thinking he was witnessing a ‘miracle’, while in reality he was witnessing a genuine phenomenon in the Jerusalem of Asir whose existence is proposed by Professor Salibi, not the later one of Palestine. The fact of the retrograde motion of the shadow of a gnomon within the tropics is independently confirmed and fully explained by Denis Savoie in his book Sundials, Design, Construction and Use (English translation by Bob Mizon, Springer Praxis Publishing, 2009), Appendix F (6), pp.163-4.
I must conclude by saying that Professor Salibi nowhere impugns the religious message of the Hebrew Bible. His thesis, in The Bible Came from Arabia and in the third part of the present work, centres purely on the correct location of places mentioned in the Bible. [Note: for anyone interested, Denis Savoie provides a diagram in Appendix F (6) of his book demonstrating the shadow’s retrograde motion, as well as an explanatory mathematical formula.]
Posted by Kamal Salibi at 9:19 AM
Interesting argument. I would surely read the book at first occasion.
aboualfa said...
This article is just what i needed to furthur mess up my conception of history and it is a great feeling to know more than the others!!
I wonder if the writer's english quote of Isaiah 38:7,8 is what Dr. Salibi would have translated from old hebrew!?[ in terms of wording not the concept]
Kamal Salibi said...
to aoualfa: the translation from the Hebrew is correct in all the versions I know, including the Arabic one by Van Dyck/Butrus Bustani/Yusuf alAsir
Wolfganggr said...
Anthony Lias has really a brilliant mind.
If i knew the text, which i did not, i surely would have taken it as a parallel to the famous 'sun stand still above gideon' passage in judges, because this behaviour of a sun-dial was unknown to me.
Its really fascinating you can make such findings in a text which has been written 2800 years ago and has been studied for more than, lets say 300 years.
Kamal Salibi said...
The Hebrew for "degrees" in the original is MA`ALOTH, which can mean "steps", as in a staircase. This his given rise to much speculation as to what the "sundial" of Ahaz was like. That this sundial involved a "shadow" being cast on "steps" marking degrees is certain. What I would like to subject to further inquiry is the word rendered in the standing interpretations as the personal name "Ahaz" (cf. Arabic AKHADHA, 'take, hold"), because the text does not plainly indicae that it was the name of King Ahaz, the father of King Hezekiah. This it could well have been, but not necessarily so. (For example, it could have been, in the context, an auxiliary verb. Do not quote me on this unless I give my OK)The issue, however, does not make the least difference to the argument presented by Mr. Anthony Lias.
Kamal Salibi said...
My last comment was a postscript to my response to the query of Aboualfa. ks
Kamal Salibi said...
I fully endorse the comment of Wolfganggr. In barely two pages of text, modestly yet elegantly expressed, he has brought about a revolution not only in knowledge, but in the variety of surprising ways in which virtual certainty can be reached.
Kamal Salibi said...
Wolfgang Grassmann said:

i could prove the effect of the sundial with use of the astronomy-program 'Stellarium'.
I wonder why i haven't thougt at that at once.
I took the city of Abha as a Reference and i took to be the
Date of the Summer-Solstitium, which means the 21 of June.

I was able not only to prove the mere existence of the effect,
but also its magnitude which is very near to the ten degrees as described
in the bible.

The Azimut-Angles starts ( at sunrise , i used sunrise, but the numbers are fully the same at sunset )
at 65° 1' and it goes up to 74° 59'53'' which is approximately 75°. From that point on the shadow
goes back to lower values.
So the difference between the values is exactly ten degree, as prophecied by isahja.

This was far more that i ever imagined. :-))))

With all best wishes
Kamal Salibi said...
To Dr. Grassmann: With the information provided by the Biblical books of Isaiah and 2 Kings regarding the contrary movements of the shadow of the gnomon on the surface of the sundial of Ahaz, to what dregree can one determine the exact location of this sundial, and the time of year in which the vent took place -- if at all?
Kamal Salibi said...
correct vent took place = EVENT took place
Kamal Salibi said...
Hi Rami. Your wustion (no.2) has kept me awake nights, and no I can approach a fully satisfactory answer where the supposed name of King Ahaz (not at all central to the argument of Anthony Lias) is concerned. I would read the word as the present participle (ism fa'il) of the Hebrew AHAZ (Arabic AKHADHA), "taking". Accordingly, the Hebrew of Isaiah 38:8 would read, word for word: "Behold, I am bringing back the shadow of the degrees going down(YOREDAH, in the singular; hence uncertain so far)on the degrees that are taking(OHEZ, not AHAZ)the Sun (meaning, as in Arabic, "that follow the sun") in the opposite direction. And the Sun went back ten degrees on the degrees that are going down." This means, "Behold, I am bringing back the shadow of the degrees ten degrees on the scale (dial)that goes by the Sun in the opposite direction, and the Sun went back en degrees on the descending scale.
Had the original Hebrew said AHAZ HAM-MELEKH instead of simply 'HZ.which is readable as OHEZ, this retranslation would not hold. It still needs some touching up where I put in the query.
Thank you for calling my attention to a matter I should have noticed myself.
aboualfa said...
Well, i wondered at the beginning how come Dr. Salibi let Isaiah 38:7,8 slide without his personal touch!! It turned out you didn't after all! And the re-translation solidified the meaning and was not peripheral to it which made it more convincing.
rami aboualfa
Kamal Salibi said...
I have checked, and the queried part of he tradslaton is correct. YOREDHAH is the adverbial form of YOREDH, which in Hebrew is identical with the feminine (not "singular" which, though correct, was a typing mistake) fo YOREDH, meaning "going wond," and hence means "going down" as an adverb. Again, I thank you for your perceptive -- and very helpful -- comment on a subject which may be abstruse, yet is nonetheless of the first importance.


  1. Priest Ezekiel writes of machines, wheels within wheels in the Old Testament. I have written a book titled 'Raising Stone 1' which explains the ancient (rampless) method of Giza Pyramid construction. Well I was puzzled that Ezekiel refers to the northern direction for Pyramid building activity, however if the account originated at Asir then the northern direction makes complete sense. I have a copy of Prof. Saliba's book and consider it to be most plausible.
    Regards, Paul Hai, Mount Isa, Australia.

  2. Read Mr Harold Hill ,Nasser programme,how they discovered the missing 24 hours in astronomy,they had to use the Bible ,God must have an enormous smile on his face.article appeared in "English Churchman",15th Jan: 1971

  3. Read Mr Harold Hill,Nasser Programme,how they discovered the missing 24hours in astronomy,crucial to satelite navigation,article in ,"English Churchman",15 Jan,1971 , David Gray