The Accuracy of The
Astronomical Calculations

We got several E-mails in which we were requested to provide our opinion in the astronomical calculations accuracy. Even though, I don't see that this matter deserves a special page, since it is already a finished argument, we will deal with it to make it very clear.

Most claims which attribute the calculations to be inaccurate come from those who believe in the Saudi claims of seeing the crescent, when the Moon is not even in the sky, or it didn't reach the conjunction yet ! The evidences for the calculations' accuracy are much more than to be mentioned in one page ! However, we shall discuss this issue by replying upon an E-mail we got from one of our friends in UK, who is: Br. Yusuf Karolia. (Notice that Br. Yusuf is not against the astronomical calculations. On the contrary, he does believe in the calculations' accuracy. But I found his questions good enough to be answered.)

Assalamoalaikum Br. Odeh,

Please could you tell me how accurate predicted new moon dates are ? Have they ever been proved wrong ?

Let me give few examples for the astronomical calculations accuracy.

• During the Moon's revolution around the Earth, it might hide a start behind it. This disappearance of the start (or any other object) behind the Moon is called "Occultation". We won't mention the great benefits for observing the occultation and timing the instant at which the star disappear or reappear from behind the Moon's disk. since this is not our purpose. Anyway, in cooperation with the International Occultation Timing Association (IOTA) we got an astronomical software which predicts the times of the occultations for the nearest second. At that time we established the Occultation Observation Committee in JAS, and since then we observed many occultations. NOT SURPRISINGLY, ALL the occultations happened exactly at the same predicted SECOND! That means the calculations are VERY accurate for both; the Moon's motion and the coordinates of the star.

  For example, on 22 March 1999, there was an occultation for Aldebaran (a bright star) behind the Moon. The astronomical calculations showed that the Moon will hide Aldebaran at 21:35:41 local time (UTC+2) as seen from Amman, and so the Occultation Observation Committee in JAS went to observe this event. At that time, we switched on the radio to hear the time signals (A special station which transmits the time as a Peep every second continuously). In Jordan the best one is that transmitted from Moscow. It can be heard at the Shortwave band at 2.5, 5, 10, 15, 20 MHz. But mostly you will need an external antenna. Anyway, we were able to see Aldebaran until 21:35:40, and as we heard the the 41st peep the star disappeared. What an accuracy! Knowing that the same had happened several times.

• You who claim the inaccuracy.... Did u ever try to watch a solar eclipse? I'm very sure that if you observed a solar eclipse, then you would completely be convinced of the accuracy. Since the solar eclipse begins at the same predicted instant. If you don't believe, then simply observe a solar eclipse!

• Lastly, the new computerized telescopes are able to move automatically to the object you wish, just by typing its name. In Jordan we have such telescopes, which are Meade LX200 for example, and we tried this many times; As we input the coordinates of the Moon then it directly moves towards it. Notice that this needs two kinds of accuracy; Firstly, the Moon's coordinates must be accurate. Secondly, the telescope motion must be accurate too. Else, the telescope will not point towards the Moon.

Highly notice, the evidences which we mentioned above are strictly related to the Moon's motion. That is the point of disagreement between us and those who claim the inaccuracy of the calculations for the crescent. I wonder, if the calculations are ALWAYS accurate and able to locate the Moon precisely, then why it becomes inaccurate ONLY when we talk about the very thin crescent! There are many many evidences but I believe that the above ones are quit enough.

How many years are they predicted for ?

Good question, the predictions are not short-lived, that you can't know the time for the New Moon for the upcoming years ! For example, I have a book entitled "Astronomical Tables of the Sun, Moon and Planets", by Jean Meeus, in which there is a table of the times of all the Moon phases from 1970 - 2050 AD! And the times are accurate to the nearest second. This does not mean we can't get times for years out of this range! No at all, for example you are able to get the times for other years by using some astronomical software which can be found by free in the internet.

I am really puzzled because if you remember the crescent was reported to be sighted in Yorkshire UK at Ramadan Eid consistent with Saudi announcement. Also at Bury UK a large number of muslim students at the Islamic university sighted the crescent on 17th March which according to astronomers is impossible. This again is consistent with Saudi announcement. Please explain. Is there any possibility even remote that new moon prediction date was wrong ?

I assume that you are confident now of the accuracy of the calculations. So, the question that arises is: What did they see !?!?

• Let me start by this quotation from the South African Astronomical Observatory (SAAO) site: "Sightings have been reported when the crescent was not even above the horizon, or before astronomical new moon. A low-contrast brightness/ haziness structure is commonly present in the twilight sky. In addition extended staring can produce fatigue. For these and other reasons, such as an understandable mental bias in favor of a successful outcome, self-deception must be carefully avoided. Remember that a conservative judgment of non-sighting with your best effort is USEFUL information for refining visibility criteria, whereas false positives only confuse the issue."

  This is absolutely right, persons who do not have enough knowledge in astronomy might see another object and think of it as the crescent ! It could be Venus, as well as some atmospheric phenomena, such as the clouds, where it could form some thing similar to the crescent. On the other hand, he who insists on seeing the crescent might imagine it. This happens even with the astronomers !

• At the official Jordanian meeting in Ramadan 1419 AH, a witness swore that he saw the crescent on Friday 18 December 1998 from a city near Amman, knowing that the Moon didn't reach the conjunction yet at that time, and the Moon set BEFORE the sunset. He said:-
  • He saw the crescent during the Maghreb Prayer, and he was able to see it for 5 minutes.
  • It was seen by naked eyes
  • All the persons with him saw the crescent.
  • It was somehow about 30 degrees above the horizon!

  Okay, let us assume that he really saw the crescent.
  If the crescent was visible on Friday by naked eyes for the ordinary people, then it will be DEFINITELY VERY obvious for all the people on the next day? Is not it!? BUT on SATURDAY (Not Friday), 17 observers of JAS in different locations did NOT see the crescent after the sunset! Knowing that the observers were observing by naked eyes, binoculars and telescopes! On the same day observers in Saudi Arabia and Egypt informed us that they didn't see the crescent even by their telescopes. What a superb vision that person has! He was able to see the crescent on Friday by his naked eyes, and the astronomers equipped with telescopes in different countries didn't see the same crescent after 24 hours! This is a miracle!

  He said that the crescent was about 30 degrees above the horizon. Okay, notice the following:-

  • The astronomical calculations showed that the crescent was about two degrees BELOW the horizon when that person claimed it was 30 degrees above the horizon! What an accuracy the astronomical calculations have! The calculations are wrong by 32 degrees! I can't imagine that any person can believe this. Did any person saw the Sun sets two hours before its predicted time!

  • If the crescent was that high, then why didn't we see it!? At that height it MUST be visibly for ALL the people, even for those with a bad vision. I don't think the astronomer have that sever bad vision!

  • The crescent which has 30 degrees height above the horizon at the sunset, is definitely more than TWO days age ! Do think the calculations have an error of two days!? We have just mentioned above that they are accurate to the nearest SECOND, not to the nearest "two days"!

    So what did he see? I really do not know. It is rather better to ask him as well as those who enjoy this extreme superb vision which enables them to see things beyond the horizon. I really envy them for their vision !

I'd like to say that what we have mentioned here is neither an invention, nor a new theory that we are trying to prove. All what we have mentioned is considered as a very BASIC FACTS in astronomy.