Lebanon, Yemen, and Iraq confirmed that Saturday, May 27, will be the first day of Ramadan 2017.

Turkey - along with Muslim communities in Europe, the US, Canada and Australia - previously declared that Saturday will be the first day of Ramadan, based on astronomical calculations of the new moon birth.

Saudi Arabia's High Judicial Court announced that the moon was not sighted on Thursday evening, and that it will convene on Friday evening for moon sighting again.

Qatar, Bahrain, Kuwait and the UAE made similar announcements, and will make the call on Friday evening.

#المحكمة_العليا : لم يرد إلينا مايثبت رؤية هلال #رمضان ، وستعقد المحكمة جلسة مساء غد وتعلن مايثبت لديها . #واس pic.twitter.com/cqVEJiwPax — واس (@spagov) May 25, 2017

This is unprecedented, as a lunar month can only be 29 or 30 days, and according to the Saudi Umm al-Qura calendar cited by the court, Thursday was the 29th of Shaban, the last lunar month before Ramadan.

ِAs per the Umm al-Qura calendar, and Turkey, Shaban started on April 27, but as the Saudi court explains moon sighting then was not confirmed, and so there is uncertainty over Shaban's actual start.

Egypt, Malaysia and other countries started Shaban on April 28, and will be sighting Ramadan's moon on Friday evening. For them, Friday, not Thursday, is the 29th of Shaban.

According to astronomers, the new Ramadan moon will be visible on Friday around the world, either directly with the naked eye or with a telescope.

Crescent Visibility Combined Report for Ramadan 1438 & Shawwal 1438 https://t.co/0arhzPAXyJ pic.twitter.com/7BLOIbbKka — Mundhir (@Mundhir) May 20, 2017

In Yemen, rival parties have both announced Saturday as Ramadan's first day.

EXPLAINED: Why Ramadan is so important