Madam, - I'd like to congratulate Cyril Byrne on his delightful photograph of the crescent Moon over the Dublin mosque in Tuesday's edition. The sight of the slender crescent is often an unexpected pleasure but, if one knows when and where to look, it can be an interesting pursuit throughout the year.
The lunar crescent after New Moon has an important role in the Islamic calendar in determining the start of Ramadan, while amateur astronomers worldwide also regularly attempt to claim the earliest sighting record (the current record with the unaided eye is a little over 15 hours after New Moon).
Given a clear western horizon, people may spot the New Moon of May 27th this year as a breathtakingly thin curl just 17 hours old (though optical aid may be required from our latitude).
Apart from these tilts at records, the young Moon is also an opportunity to spy a phenomenon first explained by Leonardo da Vinci. This is earthshine, more commonly termed "the Old Moon in the New Moon's arms".
Look closely at the crescent the first few days after New Moon and you will see the rest of the lunar disc glowing with a dim light. This is due to sunlight reflected off Earth and on to the part of the Moon not directly illuminated by the Sun. If fact, an observer on the Moon at this time would see a nearly full Earth.
More details on the Moon and other sky phenomena throughout the year can be found at www.irishastrosoc.org. - Yours, etc,
JOHN FLANNERY, Chairperson, South Dublin Astronomical Society, Dublin 6w.