The mysterious chancel ceiling at St. John's Anglican Church in Lunenburg, N.S., was reconstructed in 2004 after a fire three years earlier. While locals now know what the star pattern represents, they don't know who originally designed it, or how. (CBC)

Parishioners at one of Canada's oldest Anglican churches will be puzzled by an enduring enigma when they gaze heavenward this Christmas.

The chancel ceiling at St. John's Anglican Church in Lunenburg, N.S., has a special pattern of gilded stars on it, and while locals now know what it represents, they have yet to find out who originally designed it, or how.

The conundrum emerged after the church, built in 1754, burned on Halloween night in 2001 as a result of arson. The parish sought to reconstruct the building's interior as closely as possible, and it brought in parishioner Margaret Coolen in 2004 to re-create the ceiling over the altar.

A fire ravaged St. John's Anglican Church in 2001. (CBC)

But the church didn't have a complete set of photographs of the original star pattern, so Coolen, hoping the pattern reflected the actual alignment of heavenly bodies in the night sky, sought the help of astronomer David Turner of Saint Mary's University in Halifax.

That's when the first mystery emerged.

Turner recognized the constellation Perseus in the photos of the eastern part of the chancel ceiling. But Perseus, seen from Lunenburg, always lies in the northern part of the sky and never due east.

"We looked at them and didn't recognize any of the star groups," Coolen explained of the constellations' positions. "It looked like they might just simply be put up at random, but it didn't seem like someone would go to that trouble to put just random stars on the ceiling."

Coolen suggested that Turner instead look at the stars' alignment around 2,000 years ago — on Christmas Eve in the year of Jesus' birth.

Then, using software that plots the positions of heavenly bodies throughout history, Turner had a revelation: The chancel ceiling's pattern indeed reflected quite closely how the night sky would have looked from Lunenburg all those years past, when constellations appeared in somewhat different locations than today.

"I set the scene for sunset, and bingo! I found myself looking at Perseus in the eastern sky," he said.

But while the finding has excited parishioners at St. John's Anglican, who now know that they are gazing up at the heavens as they would have appeared on the eve of their Saviour's birth, it has also perplexed them.

The ornamentation they once merely called "Mariner's Sky" holds a stellar motif of immense astronomical significance. But who could possibly have calculated the astral positions, and how, remains a mystery.