Light and shadow phenomena at Irish passage tombs. Martin Brennan studied sunrises at Irish mounds, documenting dramatic light effects at sites like Loughcrew At equinox, sun enters through a narrowed entrance as a small beam onto a backstone carved with symbols Moving sunlight progressively picks out carved symbols one by one on the backstone

At Loughcrew's passage tombs, Martin Brennan documented something magical 🌞 At equinox, sunlight narrows through the entrance as a thin beam, then slowly moves across a backstone, illuminating carved symbols one by one. Brennan spent decades studying these Irish mounds, unlocking the astronomical alignments of Stone Age builders. Imagine witnessing that!

Key Facts

  • Martin Brennan studied sunrises at Irish mounds, documenting dramatic light effects at sites like Loughcrew
  • At equinox, sun enters through a narrowed entrance as a small beam onto a backstone carved with symbols
  • Moving sunlight progressively picks out carved symbols one by one on the backstone
  • At Avebury near the obelisk, the top of Silbury Hill is visible, offering opportunity for light and shadow drama
  • Scully (Yale professor) photographed similar light/shadow effects in Irish sites that created mythological illusions

Related site: Loughcrew — view location, images, and history on the Ancient Nerds map.