Exceptionally high tides caused by a rare conjunction of celestial events could have placed the fateful iceberg in the Titanic's path.
The Titanic collided with an iceberg the night of April 14, 1912 and sank within hours, with the loss of around 1,500 lives.
And according to a team at Texas State University, an unusually close approach of the moon three months earlier could have raised water levels, refloating hundreds of beached icebergs.
On January 4 that year, the moon and sun had lined up in such a way their gravitational pulls enhanced each other - an effect well-known as a spring tide.
But, on top of this, the moon’s perigee — its closest approach to Earth — was the nearest in 1,400 years, and came within six minutes of a full moon. Enhancing the effect, the Earth’s perihelion — its closest approach to the sun — took place the day before.
"It was the closest approach of the moon to the Earth in more than 1,400 years, and this configuration maximized the moon’s tide-raising forces on Earth’s oceans. That’s remarkable," says physicist Donald Olson.
"The full moon could be any time of the month. The perigee could be any time of the month. Think of how many minutes there are in a month."
The north Atlantic was full of icebergs that spring - indeed, shipping lanes were moved many miles to the south for the whole of the 1912 season.
The researchers' first theory was that the increased tides had caused a rise in calving. But they quickly discounted this idea, realizing that in order to reach the shipping lanes by April when the Titanic sank, any icebergs breaking off the Greenland glaciers in January would have to have moved unusually fast and against prevailing currents.
The team's now suggesting that the answer lies in grounded and stranded icebergs. As Greenland icebergs travel southward, many become stuck in the shallow waters off the coasts of Labrador and Newfoundland. Normally, they stay there until they’ve melted enough to refloat, or a high enough tide frees them.
But the unusually high tide that January, they say, would have freed many more than usual, and would have moved them back into the southbound ocean currents just in time to rendezvous with the Titanic.
"As icebergs travel south, they often drift into shallow water and pause along the coasts of Labrador and Newfoundland. But an extremely high spring tide could refloat them, and the ebb tide would carry them back out into the Labrador Current where the icebergs would resume drifting southward," says Olson.
"That could explain the abundant icebergs in the spring of 1912. We don’t claim to know exactly where the Titanic iceberg was in January 1912 — nobody can know that - but this is a plausible scenario intended to be scientifically reasonable."