The Shawwal moon is predicted to be visible to the unaided eye on Friday evening rather than Thursday in Saudi Arabia and the United Arab Emirates. So Eid al-Fitr could start on Saturday, astronomers say.

Although the moon will technically be visible in the sky on Thursday evening, Majid Abu Zahra of the Jeddah Astronomical Society warned that it won’t be lighted by the sun and will be impossible to observe without specialised equipment.

According to Abu Zahra, the moon would be “very easy to see with the naked eye if the sky is clear,” on Friday night, according to the Saudi Press Agency (SPA).

However, if Thursday’s moon observations by eyewitnesses are accepted, authorities might still proclaim Friday to be the first day of Eid.

The Supreme Court of Saudi Arabia has previously urged citizens of the Kingdom to look for the moon on Thursday night, which would mark the end of Ramadan.

The moon won’t be visible from anywhere in the Islamic world on Thursday, according to a Tweet from Abu Dhabi’s International Astronomy Centre, with the exception of some regions of West Africa if a telescope is used and the weather is favourable.

The moon is not expected to be visible on Thursday evening due to astronomical conditions, but the centre said it’s possible that officials will still accept eyewitness testimony and Eid al-Fitr will still start on Friday.

On a number of previous instances, Eid al-Fitr had started on a day when it was technically impossible to see the Shawwal moon.

The Shawwal moon will occur on Thursday, coupled with an unusual astronomical event that will cause a rare “hybrid eclipse” that will be seen from portions of the Southern Hemisphere, including Australia and Indonesia.