SWT astronomers say WWII cruiser Indianapolis sunk by the moon

SAN MARCOS, TEXAS — Astronomers at Southwest Texas State University say one of the most horrific events in the history of the United States Navy had an unlikely culprit – the moon.

In the waning weeks of World War II, some 900 U.S. sailors and Marines died when their cruiser, the USS Indianapolis, was sunk in the Pacific. The event happened around midnight on the night of July 29-30, 1945.

Three hundred died in the initial explosions caused by two torpedoes fired from a Japanese submarine. Another 600 men died harrowing deaths from shark attack and exposure as they drifted in the ocean, awaiting rescue for more than four days. Only 317 survived the event.

Those days in the water were so horrible they earned a place in Naval history and in American film lore as well. Quint, the obsessed shark hunter played by Robert Shaw in the 1975 movie Jaws, explains in one scene that his hatred of sharks stems from his experience in the ocean as an Indianapolis survivor.

The circumstances surrounding the sinking of the Indianapolis have been the subject of controversy and contradiction over the years. Did alleged negligence on the part of the Indianapolis captain, as U.S. Navy officials later claimed, play a role in the disaster? Was it the extraordinary skill of the Japanese sub commander and his crew that sent the Indianapolis to the bottom of the Pacific? What were visibility conditions like that night, and how did they contribute to events?

Now, 57 years after the tragedy, astronomers at Southwest Texas State University say they have answered an important part of the puzzle.

The Indianapolis was doomed by the moon.

SWT physics professors Donald Olson and Russell Doescher and one of their former students, Brandon Johns, published their findings in the July 2002 edition of Sky & Telescope magazine.

Olson said the research by the trio led to three important findings about the event. First, they identified the correct phase of the moon that night, a matter that had been subject to much contradiction over the years. Second, the alignment of the Japanese submarine, the Indianapolis and the moon contributed significantly to the demise of the Indianapolis. And, third, they say that because of the alignment of the submarine, the cruiser and the moon, the Japanese were able to spot their target from a remarkable distance.

“The moon was 75 percent illuminated that night, and that differs from past accounts that have said, variously, that there was a crescent moon, a half moon or even a full moon,” said Olson.

The researchers also learned that, in order from west to east, the Japanese submarine I-58, the Indianapolis and the moon were in almost perfect alignment. As a result, when the Japanese submarine surfaced to scout for enemy ships, a crewman almost immediately spotted the Indianapolis clearly silhouetted against the bright moonlit sky. That allowed the sub to quickly dive for cover and follow a course to intercept and fire upon the Indianapolis.

Using known coordinates for the Indianapolis just before it was hit, and also knowing the running speed of both vessels, Olson, Johns and Doescher were able to determine that the sub’s crew spotted the Indianapolis from a distance of 16.5 kilometers (10.3 miles), nearly 5 kilometers more than is considered likely under good visibility conditions.

“A sighting from that distance was possible because of the alignment of the two vessels, with the moon backlighting the Indianapolis,” said Olson.

The captain of the Indianapolis, Charles B. McVay, survived the sinking and was later charged by the Navy with hazarding his ship by failing to steer a zigzag course during “good visibility.” The zigzagging tactic was used by Navy commanders to make their ships more difficult targets. McVay was convicted. In 1968, he took his own life. In 2000, Congress passed a resolution clearing McVay of wrongdoing.

Eyewitness accounts differ as to the quality of the visibility on that tragic evening. Some say visibility was poor. Others say it was poor when the moon was obscured by the clouds, but good when it was not.

Olson agrees that visibility would change with cloud cover, but says it would also depend greatly on an individual’s point of view.

“The Japanese, looking to the east toward the Indianapolis, would have excellent visibility when the moon shone between the clouds, much better than normal, in fact. But the sky and ocean were bright in this one direction only. Visibility would not have been nearly that good looking westward from the Indianapolis,” Olson said.

This July 29, the 57th anniversary of the sinking of the Indianapolis, the moon will recreate its phase of that fateful night, when a ship and its crew became victims of the enemy and of a cosmic coincidence.

While the USS Indianapolis became synonymous with one of the most tragic single-vessel disasters in all of U.S. Naval warfare, it had secured its place in world history only three days earlier. On July 26, it had completed a historic run from San Francisco to the island of Tinian, where it offloaded its cargo -- the uranium core for “Little Boy,” the atomic bomb that would be dropped on Hiroshima on Aug. 6.