Internet tells me that Gregorian date 19th of July, year 2023 is the first of Muharram. But when I try to calculate the moon phase via perl, (module Astro::MoonPhase), it tells me that on sunset with coordinates for Mecca ($latitude = "+21.422510"; $longitude = "+39.826168";), the moon was already more than half a day old at sunset on **18th** of July. What's wrong? Are the results from the computation wrong, or am I missing something in the interpretation of the computation? (Maybe both?)

After posting the question https://islam.meta.stackexchange.com/questions/1767/are-questions-on-the-historical-inauguration-of-some-utilities-or-methods-on on meta I finally decided to ask ask it here: I'm pretty sure that calendars or methods to calculate the moon phases have been developed in the golden ages of islamic caliphates, as there have been lots of scientists such al-Biruni (even Imam Malik has been said to have written a book about that) and many others. But what I'd like to know is: When and where scholars or clerics introduced or accepted them as a utility for declaring or calculating important dates like 1st day of Ramadan? Any details on this historical inauguration would be fine! I think of information like: how was the general acceptance at the time, who was the cleric, who was the person or scientists whom's caclulation methods or calendar was accepted ...

I was curious why Islam uses the lunar calendar. The solar calendar seems more pragmatic because the same date falls in the same season every year. E.g. thanks to the solar calendar, it is easy to know that January 1, 1786 was winter in Copenhagen. It is much harder to derive the season in different geographic locations based on a lunar date. The only advantage to the lunar calendar I can think of is to diversify the difficulty of the Ramadan fast, to make it easier in some years and harder in others. But are there any other benefits of and reasons why Islam uses it?

The pre-Islamic Arabs had 354 days in their calendar rather than the 365 days of the solar calendar. To make up this difference, leap months were added once every three years. But this practice was discontinued in the year 629, and the Qur'an even forbids adding leap months (Qur'an 9:36-37). Biographers like Ibn Ishaq record the month in which the events of Muhammad's life took place. Yet, Muhammad is never recorded doing anything on a leap month. Why is this?

 Islam follows a lunar calendar. Obviously, the month changes at the site of first crescent of the new moon and this happens only at sunset. It therefore implies that a date too should change at sunset. This methodology is followed universally in Islam. I could find this hadith that indirectly backs up this methodology: >### Sunan Abi Dawud (Hadith 2341) > >**Narrated Ikrimah:** > >Once the people doubted the appearance of the moon of Ramadan, and intended neither to offer the tarawih prayer nor to keep fast. A bedouin came from al-Harrah and testified that he had sighted the moon. He was brought to the Prophet (ﷺ). He asked: Do you testify that there is no god but Allah, and that I am the Messenger of Allah? He said: Yes; and he testified that he had sighted the moon. He commanded Bilal who announced to the people to offer the tarawih prayer and to keep fast. In another hadith (Sahih), The Holy Prophet (ﷺ) calls the 'Asr prayer *'middle prayer'* >### Jami' Tirmidhi (Hadith 3250) > >**Narrated Samurah bin Jundab:** > >"The Prophet of Allah (ﷺ) said: 'The middle Salat is Salat Al-'Asr.'" When the day is believed to be commenced with the sunset, the Maghrib prayer should be the first prayer and 'Asr should be the last prayer and the middle prayer should actually be Fajr. - Why then is 'Asr prayer called the *middle prayer*? - If it is a different context that the hadith refers to, what is that context and how does it make 'Asr the *middle prayer*? # UPDATE: I stumbled upon another hadith: >### Sunan Abi Dawud (Hadith 411) >**Zaid b. Thabit said:** > >The Messenger of Allah (ﷺ) used to offer the Zuhr prayer in midday heat; and no prayer was harder on the Companions of the Messenger of Allah (ﷺ) that this one. Hence the revelation came down: "Be guardians of your prayers, and of the midmost prayer" (2:238). He (the narrator) said: There are two prayers before it and two prayers after it. In this hadith, the Zuhr prayer is called the mid-most prayer. It is also mentioned that there are two prayers before it and two prayers after it. Now again, two more questions arise. - How is this Hadith compatible with the previous hadith that mentions 'Asr as the middle prayer? - Two prayers before Zuhr means Isha and Fajr. Does the hadith also mean that the next date actually starts after Maghrib (ie. with 'Isha)?

While trying to analyze the difference of opinion among the scholar on moon sightings, I came across the below Hadiths: > Abu Huraira reported Allah's Messenger (ﷺ) as saying: > > Observe **fast on sighting it** (the new moon) and **break (fast) on > sighting it** (the new moon), but if the sky is cloudy for you, then > complete the number (of thirty). > > Sahih Muslim 1081, Book 13, Hadith 21 and Narrated Hudhayfah: > The Prophet (ﷺ) said: Do not fast (for Ramadan) before the coming of > the month **until you sight the moon or complete the number (of thirty > days)**; then fast until you sight the moon or complete the number (of > thirty days). > > Sunan Abi Dawud 2326, Book 14, Hadith 14 and > Narrated Kuraib: That Umm al-Fadl, daughter of al-Harith, sent him to > Mu'aqiyah in Syria. He said: I came to syria and performed her work. > The moon of Ramadan appeared while I was in Syria. We sighted the moon > on the night of Friday. When I came to Median towards the end of the > month (of Ramadan), Ibn 'Abbas asked me about the moon. He said: When > did you sight the moon ? I said: I sighted it on the night of Friday. > He asked: Did you sight it yourself ? I said: Yes, and the people > sighted it. They fasted and Mu'awiyah also fasted. He said: But we > sighted it on the night of saturday. Since then **we have been fasting > until we complete thirty days or we sight it**. Then I said: Are the > sighting of the moon by Mu'awiyah and his fasts not sufficient for us? > He replied: No. ***The Messenger of Allah (ﷺ) commanded us to do > so.*** > > Sunan Abi Dawud 2332, Book 14, Hadith 20 and > Narrated Abdullah bin Umar: > > Allah's Messenger (ﷺ) said, "The month (can be) 29 nights (i.e. days), > and **do not fast till you see the moon, and if the sky is overcast, > then complete Sha'ban as thirty days.**" > >Sahih al-Bukhari 1907, Book 30, Hadith 17 My limited understanding of the subject leads me to believe that the Islamic month starts when the new moon is sighted. If it is not sighted due to clouds or some other reasons (volcanic eruptions, sand storms, smog etc), then the next night is considered to be first night of the new month. But I'm confused when people say that even tough the moon isn't sighted it was born by astronomical calculations. Hence, Hilal is not more necessary. My knowledge tells me people of earlier times had great sophisticated knowledge when it comes to astronomy and surely at the time of the Prophet (SAW), people knew how to calculate lunar cycles, eclipses, movement of stars and constellations. So is there something I am missing that the present day ulema are in disagreement over moon sighting and bring confusion among the masses atleast twice a year.

I am developing an application which allows users to convert from Gregorian to Hijri dates and vice-versa. I am thinking about whether to just have an input box for the date (e.g. 8/21/2021), or to have an additional input box for the time (e.g. 6:00 AM), as I have heard from others that a new day in the Hijri calendar can start in the same day in the Gregorian calendar? Furthermore, does the Islamic Hijri calendar run on a standard 24-hour day just like the Gregorian calendar?

I understand the Islamic day begins at sunset/maghrib (e.g. https://islam.stackexchange.com/questions/24725/if-the-date-changes-with-sunset-why-is-asr-called-the-middle-prayer) . However, it is less clear whether the daily 24 hour clock also begins (i.e. 00:00 (0 hours and 0 minutes)) at this time, as practised by countries or major international organisations which adopt the Islamic calendar. I would be grateful if members here could inform as to the whether it does? And if not (e.g. it starts at the (Gregorian calendar) midnight), why this is the case? That is, the justifications (especially theological/fiqh (vs practical/logistical) for the discrepancy between the accepted theological basis of the start of the day, and the actual practice?. Thank you.

When we start a new day, we usually start it at 12am. But what about in Islam? Does a new day start at Maghrib time or Fajr time? Someone told me it is either one of those times. Is this true? What is a new day or next day considered in Islam?

What if at any 29th day of the month, the weather is always bad, so you can't observe anything, so that you always need to add a 30th day to the month And what if at the contrary, you can always observe the moon at the 29th day and all your months are only 29 days I think the second case can not be possible as the moon doesn't do a cycle every 29 day but 29,5 days, so you should be able to keep a good pace with the observation But in the first case, their calendar will be late, their year will last longer So is there any other system (than observing at the 29th day) to correct a bad weather in order to correct the calendar, to synchronize a way or another? It's already difficult some months where all countries have difficulties not to be synchronized (in the same country people fight each-other to know when begin ramadhan), but over a year, it's impossible (12 day difference per year maximum, so a completely different calendar depending on the country)

I don't understand why God choose 12 month per year why not 53 10 9 because 12 is a special number we know with the qur'an that 1 month means one lunar cycle and there is exactly 12 lunar cycle EVERY year I don't understand since our hijri calendar doesn't care about solar year and also I don't understand why some people claimed that prophet was following a solar year in the early days of Islam I am not sure if this calendar is the right can you help me explaining why 12? maybe there is other reason

As far as I know the Jewish calendar is (or was) a lunar calendar as our Islamic calendar. And among Muslims the hadith of ibn 'Abbas saying that Jews in Medina used to fast the 10th of Muharram is well known. So why the days of 'Ashura' and Pesach don't fall together?

Suppose somebody went on an island and don't have sense about time, dates, months. The only thing he has is seeing the sky. Is it possible to recognise which lunar month it is by just looking the sky? I ask this because I know how to see beginning of the lunar month, but how to recognise which month is it? So we can look at the Sun, Moon, the stars. Is there a way to figure that out?

Here in South Africa, we sight the moon according to the Sunnah to determine whether it is the start of Ramadan, or the end respectively. And not every location in South Africa gets to sight the moon. So a lot of towns and cities wait to hear from our Imam as the Musjid as to whether any other confirmed sightings took place, and whether or not Ramadan will start on that night, or whether Eid eve is upon us, and so on. This is all achieved with telephone, mobile phone, and internet. There is a very short time span between Maghreb (when the moon can be sighted) and Esha, the night prayer - before which the sighting must be confirmed - so the only way we acquire confirmation in such a short period is thanks to technology. But how did they do it during the Prophet's (PBUH) & Sahaba's (MABPWT) time? If the moon was sighted in Medina, but not Makkah, how did they pass the message on fast enough? This would also apply to just maintaining the lunar calendar. Ignoring Eid and Ramadan, they would have needed a consistent way to keep the lunar calendar constant throughough specific towns, and cities within the same location....so how did this all happen? I tried searching for an answer by Googling, but I don't think I'm using the correct phrasing - or maybe nobody's asked. Thanks.

There is always confusion of moon sighting and deciding on Eid but I hear somewhere that the moon need to be a certain percentage to say it will be Eid next day. If that is true then what is a percentage of the moon sighting?

Assalamualaikum and Hello to all, As a muslim experiencing Ramadhan in Europe, presently in summers, with it's long hours, has led me to think about when I experienced it in winters here when I was a child. Specifically, I was wondering how long does it take for Ramadhan to move from one season into the next? How long will it be before I experience Ramadhan in winter, after experiencing in summer for some years now? I will offer some thoughts as an answer, but I'd be grateful for any further thoughts. Wassalam and best regards.

In Arabic dates off the week are numbered 1-7. In English and other similar languages, they are named after 'gods' and 'goddesses'. But hoe it's or that the Friday of one week matches the equivalent of the Islamic week? Why are they not misaligned liked the months (albeit with a fixed offset)?

What are the evidences for each view and it is not as easy as just following the new moon in your country I believe because there are many issues which even experienced scholars find it hard to understand.

I wonder, why does the Islamic new year start in the month of Muharram. As Muslims start their calendar with the immigration of the Holy Prophet from Mecca to Medina, known as Hijra, the first day of the year should be in the month (Rabbi ul Awwal) the Prophet left for Medina.

Is there any ibadah prescribed by Prophet Muhammad (peace be upon him) for the night of 27th Rajab?