Each year, as Ramadan approaches, more than 2 billion Muslims around the world prepare for a month of fasting, prayer, and communal activities. However, Ramadan does not start on the same day everywhere in the world.

This year, the month of fasting begins on Thursday, February 19th in some countries, while in others it begins one day earlier. Similarly, at the end of Ramadan, different communities celebrate Eid on different days.

The reason lies in the nature of the lunar visibility calendar. The new crescent moon is not always visible everywhere on the same day. Prophet Muhammad is is reported to have said: “If you find it, observe it immediately. [the crescent] If you find it, fast. [the next crescent] – However, if the sky is cloudy, please complete the number [30 days]”

In modern times, there are several countries such as: turkey We implemented a calendar reform and removed the act of visually observing the crescent moon every month. Instead, it relies on predetermined calculations.

Nevertheless, visually observing the moon to determine the beginning of the month is still a habit for the majority of Muslims around the world. Most people believe that this must be done with the naked eye.

Therefore, cloud cover can affect the start of the month in different locations, resulting in an unpredictable calendar. This infuses the moongazing occasion with a sense of communal wonder, but it can also cause problems. surprisingly controversial.

a very British problem

When Muslim immigrants who arrived in Britain in the mid-20th century tried to observe the New Crescent, they often had a hard time. One of the reasons was cloudy weather, a very British problem.

As a result, different mosques and communities end up outsourcing their moon observations to different countries. Some follow Morocco, others Türkiye and Saudi Arabia. Mosques in the UK may have separate dates for Ramadan and Eid, as each country may confirm a first sighting on a different date.

This is a source of distress for some members of Britain’s Muslim community. For me (Imad) growing up in London, it meant that my friends at school might start celebrating Eid on a different day than me and my family. I found this quite sad, but I just thought it was the way it was supposed to be.

Things changed during a family trip to Cape Town, South Africa, when they witnessed the community’s practice of observing the moon. When I saw thousands of Muslims flocking to the beach to see and celebrate the new crescent moon, I asked myself: “Why can’t we do this in the UK?”

When I returned from Cape Town, I founded The Club, an Islamic lunar astronomy club. New Crescent Association. Our aim is to find a way to jointly celebrate moon sightings across the UK and develop an Islamic lunar calendar that is as viable here as it is in other parts of the world.

You may be able to see the moon in Cardiff but not in Cambridge. The sky may be clear in London but cloudy in Manchester. a UK-wide astronomy education program; moonsiters academyis currently helping Muslims lead their own moon-watching groups in their communities.

Astronomy related to visibility of the moon

Each month, the moon rises from a thin crescent to fullness each night. huge (More than half full) Then it fills up, then goes down in a crescent shape and disappears again. This cycle occurs as the moon revolves around the Earth and takes 29 and a half days.

The moon does not produce its own light. What we see is reflected sunlight, and the same side of the moon is always facing us. It rotates on its axis at the same speed as it orbits the Earth. This phenomenon is tide stop.

The exact moment at which some amount of lunar illumination is first visible from Earth each month depends on geometric physics. At this point, the crescent moon is so thin that it’s difficult to see it, even with a camera.

However, as the Moon moves away from the Sun in the sky, the crescent slowly thickens as the separation angle increases. There was a longer “lag” between sunset and moonset, and the new crescent became more visible. The best time to observe a young crescent moon is about halfway between sunset and moonset, when the brightness of the sky and the moon’s altitude are balanced.

Astronomers relish the challenge of finding very thin crescent moons that are less than 24 hours old. But how young can people see the moon? with the naked eye• One established landmark of 15 hours and 32 minutes was set by astronomer Stephen James O’Meara. First discovery of Halley’s Comet When he returned in 1985.

If you introduce optical aids such as binoculars, you will be able to see an even younger and thinner crescent moon. With the right conditions and technique, it is also possible to photograph the Moon when it is exactly 0 hours old at the moment of conjunction. this is First achieved by astrophotographer Thierry Legault In July 2013, it used a telescope’s infrared filter that was “baffled” to block out the unsteadily nearby Sun.

So when do Ramadan and Eid start?

This depends on where you are in the world. A new crescent moon has been born in Saudi Arabia. Declaration on Tuesday, February 17thEven though it was only about 3 hours before sunset. So for local Muslims (and those following Saudi Arabia’s lead), Ramadan begins the following day. Wednesday, February 18th.

A solid new moon will be observed in the UK, Europe and North Africa one day later, potentially triggering fasting on Thursday 19th February. Countries further east, such as Australia, will probably see the moon a further day later, so they will observe their first fast on Friday, February 20th.

When the new moon will be visible from the UK (February 17-18):

next month, Thursday, March 19ththe moon’s sunset time will be between 17 and 18 hours, making it difficult but not impossible to see in the UK, Europe and North Africa. Therefore, it is expected that these sightings will prompt the community to start celebrating Eid. Saturday, March 21st. Mosques are likely to follow Saudi Arabia’s lead in celebrating Eid a day early.

However, this is not just about calendars. When people gather to look for a new crescent moon on the horizon, they are participating in a practice that connects them to one of humanity’s oldest practices: observing and connecting with the natural world around them. In the UK, we hope that our work will help make this celebration even more unified.