History is filled with mysteries that can be answered by the position of the moon, the nature of the tides, and the time of year when an event occurred. Here are mysteries of battles, art, and literature, that were solved thanks to astronomical detectives.


Top image: Lithograph of the Battle of Chancellorsville, where Stonewall Jackson was wounded.

Who uses the skies to solve historical mysteries? Astrophysicist and forensic astronomer Donald W. Olson and his team at Texas State University use their astronomical tools to solve all manner of mystery. You can read about more of their investigations, and get more details on each of these mysteries, in Olson's book Celestial Sleuth.

1. Why was Stonewall Jackson hit by friendly fire?

On May 2, 1863, Lieutenant General Thomas "Stonewall" Jackson was shot by his own Confederate soldiers during the Battle of Chancellorsville. It was a devastating loss for the Confederacy, as Jackson was a brilliant military strategist. General Robert E. Lee likened losing Jackson to losing his right arm. But why did it happen at all?


Historical accounts indicate that the battle was fought into the night, and Olson and his team calculated both the lunar phase and the position of the moon at the time and place that Jackson was shot. Examining historical accounts and battle maps, they pinpointed the positions of Jackson and Confederate Major John Barry, who ordered his troops to fire on the general. They found that, thanks to the moonlight, Jackson would have appeared to Barry's troops as a dark silhouette, easily mistaken for one of the enemy. Jackson may have been a tactical genius, but his decision to keep fighting into the night contributed to his death.

Edit: Commenter Totalimmortal85 notes that it wasn't the actual shots that killed Jackson. He died more than a week later of pneumonia after the amputation of his arm. The shots led indirectly to his death. Also, the main assault ended with nightfall, but Jackson decided to scout into the night.

2. Could the runner of the Marathon have really dropped dead?

You've probably heard the story: a Greek messenger was sent to Athens to announce the Greek victory over the Persians at the Battle of Marathon. He delivered his message and then promptly dropped dead from exhaustion. But could it really have happened?



Historians have long pegged the Marathon run as occurring in September, when the average maximum temperature in Athens would have been 83° F. Some runners have doubted that a soldier running that distance at that temperature would have even passed out, let alone died. But Olson's team noted that calculations that led to the September date were based on the time of a Spartan festival, the lunar phases, and…the Athenian calendar. Olson's team adjusted those earlier calculations using a Spartan calendar, calculating the date of the fall equinox and the full moon that rose over that Spartan festival. They placed the date of the Marathon run in early August, the 5th or the 6th in the modern calendar. The average afternoon temperatures would have been much higher, with possible maximum temperatures up to 102° F, a much riskier situation for the first Marathon runner.

Painting of the Marathon runner by Luc-Olivier Merson.

3. Where in Britain did Julius Caesar's invading force first land?

I suffered through Caesar's notes on the Gallic Wars, but I had no idea that they contained a small geographic mystery. Apparently, there has been great debate between historians and astronomers and hydrographers as to where in Britain Caesar and his forces landed in 55 BC. Historians have typically said the landing site must be to the northeast of Dover, while astronomers and hydrographers have insisted the Romans landed to the southwest of Dover. So who is correct?


Olson's team had a spot of good fortune while investigating this particular mystery: During certain dates in 2007, they would be able to observe the nearly exact tidal conditions that the Romans experienced during their landing thanks to the distance between the Earth and the moon weeks before the equinox. Their experience matched with what hydrographers proposed. If the landing took place on the date typically assigned to Caesar's landing, he must have landed to the southwest of Dover.

But what if the date was wrong? In their observation of the tides, the team realized that the forces could have landed to the northeast of Dover (which would fit with geographical descriptions in contemporary accounts of the landing) if the landing took place a few days earlier. The teams proposed solution to this mystery: a transcription error has long placed the landing at the wrong date. The historians were correct about the geography and the hydrographers were correct about the tides. The problem is that everyone was looking at the wrong date.

4. Could Mary Shelley's story about Frankenstein's origin be true?

Mary Shelley tells a very melodramatic, very ghostly story about the night that she came up with her most famous story. The story goes that, during a gathering at Villa Diodati, Lord Byron proposed that all of the assembled guests write their own ghost stories. Shelley claimed that she was stumped for days, until one night, when she woke from a nightmare after midnight and saw moonlight streaming into her window. The next day, she was hard at work on Frankenstein.



Fact or melodrama? We don't know for certain, but many writers have doubted Shelley's account, claiming that she must have come up with the story earlier — or that her husband, Percy Bysshe Shelley, came up with the idea. The date of Byron's challenge is often listed as June 16, 1816, even though no primary sources reference a particular date. If Byron did make the challenge on that date, then Mary Shelley's story is likely bunk. After all, days later, there would have been no moonlight to see.

However, if the challenge came earlier, within a day or so of the group's arrival at Villa Diodati, that very much changes things. Olson and his team calculated that a bright gibbous moon would have been shining right into Shelley's bedroom window at 2am on June 16, 1816. It's entirely possible that moonlight played a role in Frankenstein's inception.

5. Did the Revolutionaries use torches at the Boston Tea Party?

The Boston Tea Party is one of those events that has been memorialized in numerous works of art, but those artworks can't agree on whether it was a brilliant full-moon night, or a dark one that required the participants to carry torches. The Texas State astronomy sleuths were able to calculate that the Boston Tea Party occurred three days after the new moon, meaning that a thin eating crescent would have been visible in the sky. Forces and lanterns for everyone.


The most accurate celestial representation of the Tea Party, according to Olson, is a series of four 1973 stamps designed by William A. Smith, which depicts that small sliver of moon in the sky. Smith didn't stumble on this design by accident; he actually consulted colonial almanacs to get the phase of the moon just right.

Olson also notes, with some amusement, that their calculations also showed that the tide was extremely low that night on December 16, 1773. That means the revolutionaries were dumping the tea crates in a great deal of muck.

6. Why wasn't Paul Revere spotted during his famous Midnight Ride?

If you're familiar with Henry Wadsworth Longfellow's poem about Paul Revere's Midnight Ride, you may recall a great many references to moonlight:



Then he said "Good-night!" and with muffled oar
Silently rowed to the Charlestown shore,
Just as the moon rose over the bay,
Where swinging wide at her moorings lay
The Somerset, British man-of-war;
A phantom ship, with each mast and spar
Across the moon like a prison bar,
And a huge black hulk, that was magnified
By its own reflection in the tide.

But was this true? Was the moon rising as Revere crossed the harbor? And if so, why wasn't Revere spotted?

Well, it is true that a bright moon rose as Revere made his crossing on April 18, 1775. But it was a very unusual moon. According to calculating, the moon was in the southern extreme of its orbit that night, rising to the south of east instead of due east. Thanks to that little bit of luck, Revere was much harder to spot than he might have been otherwise.

7. Did Abraham Lincoln use a fake almanac to win a famous murder trial?

The 16th President of the United States may have been nicknamed "Honest Abe," but many people called his honesty into question in the wake of the famous "Almanac Trial." In 1858, Lincoln defended one William "Duff" Armstrong, who was accused of killing James Preston Metzler on due to injuries from a brawl. The key witness in the case claimed that he had seen the brawl in full moonlight, but Lincoln produced an almanac that showed that, at the time of the brawl, the moon would have been near the horizon, nearly out of sight. Armstrong was acquitted, but after the trial, people began to wonder if the almanac was a fake. After all, numerous people remembered seeing a bright moon that night. Should we start calling him "Dishonest Abe"?


Probably not, although there is a reason the townsfolk remember seeing such a bright moon. It turns our that the night of the brawl, the moon was at a very special point in a 18.6-year cycle. The tilt of the Earth's axis and the tilt of the lunar orbit resulted in a very unusual, extreme passage through the sky. So early in the evening, the moon did indeed cross the meridian of the sky, but just a few hours later — at the time of the brawl — it was nearly out of view. Both the almanac and the townsfolk were correct.

Image from the 1939 film Young Mr. Lincoln.

8. What is the bright object in Van Gogh's White House at Night?

Olson's team has done a lot of investigations into paintings — the works of Claude Monet, Edvard Munch, and more. Naturally, Vincent van Gogh, with his brilliant celestial paintings, is of particular interest, and the team decided to look into his White House at Night to figure out what the brilliant, star-like object that he painted in the sky actually is.



Interestingly, Olson's team discovered that the house in Auvers-sur-Oise commonly identified as the White House is not, in fact, the house Van Gogh painted. Rather, it was a different house in the town which has since been renovated. Once they were able to identify the correct location, the team was able to calculate the position of the objects in the sky while Van Gogh painted it. The brilliant object, they concluded, is Venus.

9. How was the Japanese I-58 submarine able to so easily spot the USS Indianapolis?

The sinking of the USS Indianapolis was one of the most infamous naval disasters of World War II, in large part because the survivors floated for days in shark-infested waters. But Olson and other researchers have studied the role that moonlight played in the sinking of the ship. After the cruiser delivered the Hiroshima atomic bomb to Tinian, the Japanese submarine I-58 fired upon the boat, sinking it. Amidst all of the accounts of the event, there are numerous conflicted accounts of the moonlight.

Carefully studying the data to determine the location of the submarine and the cruiser at the time I-58 spotted the USS Indianapolis, the researchers determined that the cruiser was silhouetted by a three-quarters moon. Like Stonewall Jackson, the USS Indianapolis appeared as a dark figure in the moonlight. But unlike Stonewall Jackson, it was correctly identified as the enemy.