2. Age: Youngest Moon

2.1   Question: After the Moon Birth, how much time is required for people to sight the New Moon?

Answer: Time passed after New Moon Birth is called the age of the moon. Sighting is possible at different age in different months. So, age cannot be a criterion for sighting. Why is it so? Because, the orbit of the moon is elliptical and in its orbit, the moon moves faster when it is closer to the earth, and slower when it is farther from earth. When it moves faster, the moon becomes visible at smaller age (like 17 hours), and when it moves slower, it becomes visible at larger age (like 23 hours). The main factor that makes the moon visible is the angle between moon-earth-sun. When this angle becomes about 9 degrees, the moon starts to be visible. How much time it takes to get this angle depends upon the speed of the moon in its orbit.

2.2   Question: When has the earliest new moon crescent been seen after new moon was born? (Dec 4,1997)

Answer: Moon sighting does not depend on age. Non-Muslims have treated this question as a sport, "Who can see the youngest moon." In the zeal of their competition, they claim early and early sightings, which are in most cases false, as many claims have been refuted with no sighting at places thousands of miles west. There was an article in Quarterly Journal of Royal Astronomical Society, Q.J.R. Astr. Soc. (1993) 34, p53-56, "Records for young Moon Sightings," by Bradley Schaefer, Imad Ahmad, and LeRoy Doggett. They have refuted some sighting claims. However, they accepted the two following claims:

1. Morning crescent on Sep 14, 1871, Age -15.4h at Athens Greece, seen by Schmidt (Naked eye)
2. Evening crescent on May 5, 1989, Age 13.47h East Lansing, MI, seen by Victor (Binocular only)

Both of these claims are questionable; the first one with naked eye has been a record so old that it has not been met in the recent century, and therefore is doubtful. There is no way it can be justified. The second one is questionable, as I, Khalid Shaukat had talked to Bob Victor who told me that there were two other persons with him and they could not see the moon. Moreover, from Michigan to West coast, no where it was seen. This paper also did not accept May 5, 1989 sighting of Badat in Houston reported by "Mohib Durrani." The article mentions that reported altitude was wrong. I personally talked to Badat and he told me he casually looked over his shoulder as he was standing for Maghrib prayers and he saw the moon quite high. The authentic naked eye sightings are at about 17.2 hours, and 15.5 hours by observatory telescopes. Remember, in some seasons, earliest moonsighting takes about 24 hours. So if the moon has become 17 hours old or more, one can not conclude that it is possible to see that moon.

2.3   Question: What is the record time between a new moon and its first possible sighting, and is this result available for every point on earth? (Jan 15,1998)

Answer: No, this result is certainly not available for every point on earth. According to different individual claims, the record time between new moon and its sighting varies for naked eye, and aided eye (binocular or telescope). Dr. Doggett of U.S. Naval Observatory, Dr. Schaefer of Yale University, and Dr. Ahmad, a Professional astronomer have written a research paper on a collection of most early sighting claims, Q.J.R. Astr. Soc. (1993) 34, p53-56, "Records for young Moon Sightings." For naked eye, claims are with the age 0 to 15.4 hours, but all claims less than 15 hours are not considered credible by professional experts in this field for various reasons. Some were reported a few days or weeks later, some few month later and in some cases, it was found that skies were overcast in that area, so claims were made for wrong dates. For aided eye, claims less than 13.47 hours are not considered credible.

However, one point must be understood, and that is, even if a moon was sighted at the age 15.4 hours by naked eye, or 13.47 hours by aided eye, it does not mean that every time moon age reaches those limits, it could be visible. In some months, moon could not be visible any place on the globe until it becomes 23 hours old. That still does not mean that a 23 hour old moon will always be visible from every place on the globe.

2.4   Question: What is the "scientific" basis for the apparently accepted view that the moon cannot be sighted with naked eye if it younger than 13 hours or so? (Dec 24, 1998)

Answer: Scientific basis is that in 13 hours, the angular separation of the moon from sun is between 7.2� to 8.5�. The angular separation (elongation) is the most important factor in moon's visibility besides several other factors combined. At the angle 7�, no sun light reflected from the moon can come to the earth meaning that the crescent is not formed to see from earth (This is due to the mountains on the surface of the moon that block the sunlight coming to the earth - Danjon effect). Between 7.2 and 8.5� the crescent is invisible to the eyes, because the brightness of this thin crescent is less than the sky brightness on the horizon. At elongation less than about 7.5� even telescopes do not pick the thin crescent. This is the discussion for naked eye versus telescope or binocular sightings.

The published record for moonsighting with bare eyes shows that no one has ever seen the crescent of less than 15.4 hours old [See "Records of Young Moon Sightings, Quarterly Journal of Royal Astronomical Society (1993) 34, 53-56, article by Schaefer, Ahmad, and Doggett]. This sighting was done on Sep 14, 1871 CE. The angular separation was 9.3�. That was in the previous century, when atmospheric pollution, and city light pollution did not exist. Now, it is not possible to see even this kind of crescent. In recent times the crescent that has been seen with naked eye had the angle of 10.5� which corresponds to 17 to 21 hours of age. Remember, even 17 to 21 hours age does not mean that every moon of this age will be visible. There are other factors that must meet the certain minimum for a crescent to be visible.

2.5   Question: What is the youngest new moon observation record with a telescope, binocular, and with unaided eye? (Dec 30, 1998)

Answer: We are unaware if any one keeps the record of telescope sightings. The youngest new moon observed with a binocular is 13.47 hours of age, while with unaided eye, it is 15.4 hours. [See "Records of Young Moon Sightings, Quarterly Journal of Royal Astronomical Society (1993) 34, p53-56, article by Schaefer, Ahmad, and Doggett].

FREQUENTLY ASKED QUESTIONS ON MOON-SIGHTING