|Winter Solstice Sunrise, Ireland, Sandymount Strand, 2008|
While it is uncertain whether or not the ancient Gaels celebrated the darkest night of the year (Grianstad an Gheimhridh or Meán Geimhridh as it's known in Gaeilge [Irish] today), a number of modern Gaelic Polytheists, including myself, do indeed mark this solar event. As the winter was an extremely hard time for the ancient Gaels and travel would have been short (if any took place at all), the likelihood of a grand celebration on the scale seen at Samhain looks very slim. However, some of us believe that if the Midwinter was indeed observed it would have taken the form of small, intimate, familial celebrations. This sets the stage for how most observe the day.
Family/community is the foundation of Gaelic Polytheism and so gathering together with loved ones (of choice or relation) during the dark, cold months of the year is truly something special that some feel should be commemorated. Many Gaelic Polytheists celebrate by welcoming the sunrise whilst repeating prayers from Carmina Gadelica (#316, "Hail to thee, thou sun of the seasons" being a favorite of most) and turning their thoughts to Brú na Bóinne, or Newgrange, since the tomb is illuminated by the solstice sunrise through the roof box. Others might even have all-night vigils, using the long darkness of the night for meditation, contemplation, and devotion — huddling together with family and friends to celebrate the sun when it rises.
While Brú na Bóinne is definitely a pre-Celtic passage tomb, the fact that it has myths attributed to it shows that the Gaels respected it and even possibly had rites honouring it. While we will probably never know this for certain, Midwinter is indeed an astronomical event marked by many Gaelic Polytheists today.