Once upon a time, legendary lyric poet Sappho was having a really lousy night. And while someone else might have just moped the night away, the poet set her blues to verse. Now, astronomers—who published their report in the Journal of Astronomical History and Heritage [PDF]—have a good idea of when that night was.

"Tonight I’ve Watched"

The moon and then
the Pleiades
go down

The night is now
half-gone; youth
goes; I am

in bed alone

(translator unknown)

or,

The moon has set

And the Pleiades;

It is midnight,

The time is going by,

And I sleep alone.

(translated by Henry Thornton Wharton, 1887)

Brief though it may be, this sad, relatable poem contains a surprising amount of contextual information. Yes, we know that Sappho was lonely, but we also know that on that night, it was past midnight, past moon-set, and past the setting of the star cluster known as the Pleiades.

Astronomers Manfred Cuntz and Levent Gurdemir from the University of Texas at Arlington, along with Martin George from the National Astronomical Research Institute of Thailand, took that information and ran with it. They started by compiling relevant facts from Sappho’s life: she lived on the Greek island of Lesbos; she paid a lot of attention to the skies; and she died around 570 BCE.

They also knew that earlier astronomers had previously estimated that the poem was likely written in late winter or early spring—a reasonable guess, the authors write, as that time frame is “not unusual for lyrics of an amorous nature.”

To confirm this theory, Cuntz, Gurdemir, and George started with the question of time. How did Sappho know what time it was? “We could not establish precisely what type of time-keeping device was used on Lesbos around 570 BC,” they admitted, “although we assumed that it was the clepsydra (water clock). However, a related consideration is the interpretation of ‘midnight.’ The modern time zone of Lesbos is UT + 2h, but in 570 BC times zones did not exist.”

“For that reason, we also identified the latest date on which the Pleiades would have been visible to Sappho from that location on different dates some time during the evening,” Cuntz explained in a press statement. That had to have been sometime during or before the year 570.

Next came the question of “setting.” What does it mean for stars to “set?” Stars dim as they approach the horizon. The brightest star in the Pleiades is called Alcyone. The astronomers calculated that Alcyone would have become too dim to see when it reached 3 degrees above the horizon.

The team input what they knew about Sappho’s time and space into star-mapping software and found that the poem was indeed likely written in winter or early spring—January 25 at the earliest.

“This research helps to break down the traditional silos between science and the liberal arts, by using high-precision technology to accurately date ancient poetry,” Khaledi said.

Just as importantly, the authors write, it draws attention to the work of a seriously underrated genius. “Sappho was one of the greatest Greek lyric poets, but her work has been marginalized, re-written or disregarded due to disrespect for her sexual orientation," the researchers conclude. In fact, she was more than a poet. “Sappho also needs to be placed in a broader context, as an early example of a woman in astronomy … and as an informal contributor to early Greek astronomy as well as the Greek society at large.”