December 2004 meeting "From the Blue Sky to the Zodiacal Light"


About forty members and visitors enjoyed a somewhat unusual lecture at our December meeting entitled “From the Blue Sky to the Zodiacal Light”. It was presented by John Flannery from the South Dublin Astronomical Society, an avid binocular and naked-eye observer.

This talk was structured to take us on a journey from noon through the fading twilight as the diurnal rotation of the Earth carries us into the deep dark of night. Along the way we explored the many facets of rainbows, halos, and other wonders of the sky that you can see without any observing equipment but your own eyes. The only requirement is awareness of these sights.

Why is the sky blue? It's a question we all might have asked as a child. That first glance upward in wonder introduced us to just one aspect of the marvellous world of meteorological optics. Rainbows and halos around the Moon, caused by the simple interaction of sunlight and water in its liquid or solid form, exist in many forms and are a delight to scope out when you become aware of the subtle moods of the sky.

Other delights often missed or overlooked, are Sun Dogs or “Mock Suns” Noctilucent Clouds, Aurora and various cloud patterns and formations such as Lenticular and Iridescence. John concluded his lecture with a look at what one can observe in the morning or evening twilight such as planetary conjunctions and of course the Zodiacal Light, which is rarely seen from Ireland!

Following a lively question and answer session John was presented with a small gift on behalf of the Society.


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