Czech astronomer’s ‘one-in-30-million’ photo earns NASA spotlight

A Czech astronomer’s extraordinary photograph of three objects aligning at precisely the right moment has been selected as NASA’s Astronomy Picture of the Day.

Petr Horálek’s image shows the International Space Station crossing the face of the Sun while the silhouette of an L-39 Skyfox training jet passes through the same frame. The ISS transit lasted just 0.66 seconds, and the aircraft’s appearance was entirely unexpected.

Horálek estimates that the chance of capturing both objects against the Sun at the same moment was less than one in 30 million—roughly comparable to winning a major lottery jackpot.

“This is one of the rarest images I have ever taken,” the Czech astrophotographer and physicist wrote after capturing it.

Horálek took the photograph June 8 near the village of Prasek in the Hradec Králové region. As he detailed the journey on Facebook, getting there proved almost as difficult as capturing the image.

He had planned his location carefully to photograph the ISS transit but realized during the drive that his navigation system was directing him onto a highway, and his electronic highway vignette had expired. Taking smaller roads left him with only minutes to set up his telescope and camera.

Once in position, Horálek noticed a jet performing maneuvers across a wide area of the sky. A companion joked that it might cross the Sun during the station’s transit, though he considered the possibility effectively impossible.

Seconds before the predicted transit, he centered and focused his equipment. The ISS crossed the solar disk as expected—but the jet entered the frame at virtually the same moment.

Horálek later estimated the probability by comparing the half-second overlap with his total observation time, then factoring in the area of sky covered by the aircraft’s maneuvers compared with the Sun’s apparent size.

His result of roughly one in 28.8 million does not include other variables, such as clear weather, reaching the location on time or equipment working properly.

The selection continues a strong period for Czech astrophotographers. NASA featured two Czech-authored images in August: Jakub Kuřák’s photograph Perseids from Perseus and astronomer Jakub Koukal’s Mostly Perseids.

Horálek, who works with the Institute of Physics in Opava, also recently received recognition in the Astronomy Photographer of the Year competition for an image of the Moon passing in front of Venus.

NASA has published Astronomy Picture of the Day since 1995. Horálek has appeared in the internationally followed showcase more than 50 times since 2014, alongside Czech photographers including Pavel Gabzdyl, Lukáš Veselý, Miloslav Druckmüller and Pavel Spurný.