Saudi moon-sighter Abdullah al-Khudairy, the director of the observatory of Majmaah University in Hautat Sudair, said the crescent can not be sighted if it sets before the sun, or of it sets after the sun within a certain timeframe in a certain place and if it happens that there's an eclipse.
He said: "May God bless our efforts in establishing a Muslim community of excellence and bestow upon us the strength to perform our fast with much faith and devotion".
"As the holy month begins, I wish all those celebrating a very happy and prosperous Ramadhan Kareem".
Muslims around the world are set to mark the month, during which believers abstain from eating, drinking and smoking from dawn until sunset.More news: Microsoft announces the Surface Hub 2
Before the daily fast, Muslims have a pre-dawn meal called suhoor and also come together at dusk to break the fast with the meal called iftar.
A look at some of the aspects a non-Muslim should know about Ramadan.
Redbridge CCG - the body in charge of what health services are provided in the borough - advise those fasting avoid spending long periods of time in the sun to stay healthy. Aside from fasting, the holy month of Ramadan is a month of self-reflection, sharing, caring and giving. The meal before sunrise is called suhur, while that which breaks the fast after sunset is called iftar.
President George Weah has extended heartfelt greetings to all Muslim across Liberia and the entire Islamic Community as they embark on the annual religious journey of the Holy Month of Ramadan, an Executive Mansion release said yesterday.More news: China's first indigenously built aircraft carrier leaves for sea trials
Most Muslims in the UAE fast during Ramadan (exceptions include pregnant women, elderly people, someone who is unwell) and yet go to work with the same dedication.
Students and academics at Birmingham City University in the United Kingdom have come up with a guide which aims to help people observing the month of Ramadan to make sure they eat right and look after their systems.
Ramadan is the ninth month in the Islamic (Hijri) calendar.
Eid al-Fitr follows on Friday 15 June this year.More news: Romney criticizes Jeffress as wrong man to give Jerusalem embassy prayer
Whiles prices of food are said to be soaring in parts of Nigeria due to the Ramadan, Somalia and Kenyan authorities are also feverishly undertaking measures to ensure that terrorist groups are not allowed to carry out attacks.
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