These dogs neither bark, nor bites, they don’t care if you care them or not. Moon dogs became visible on either side of the moon over the skies of Letterkenny on 15th April 2015 around 02:00am. A very pale moon pillar (the vertical line that originates from the moon) and parts of the parhelic circle (the horizontal line that starts from the moon and goes through the moon dogs) are also visible in this picture. Even though the 22 degree halos (moon rings) are common, the moon dogs are very rare to be seen.
For those who don’t know them, moon dogs are those bright spots visible on left and right side of the moon in this picture. They are also called mock moon, moondog and paraselene (the scientific term). These are caused by the hexagonal-plate-shaped ice crystals in the thin layer of cirrus or cirrostratus clouds. These bright spots appear approximately 22 degrees on the left and right side of the moon, the 22degree halo or the moon ring if exists intersects at this point. The cold weather front that made the temperature real feel to be around 0 degrees and below in Letterkenny on the Good Friday evening of 2017 would have been caused by these law flying hexagonal ice crystals (diamond dusts).