The image captures the periodic comet 13P/Olbers glowing behind the iconic East Bohemian landmark, Kunětická hora. The comet is distinguished by its two striking tails: a blue ion tail, rippling under the influence of the solar wind, and a white dust tail. The photograph was taken with a lightweight 200mm telephoto lens and a sensitive Canon Ra camera from a pre-calculated vantage point on the night of July 28-29, 2024. This location, on the western edge of the village Kunětice, is approximately 1.4 kilometers from the castle, perfectly positioning the comet directly behind it that night. The castle is softly illuminated by security lights and the faint glow of the rising moon.

The photo shoot was a blend of meticulous preparation and a stroke of luck. „On Sunday, July 28, a cold front swept across the Czech Republic, clearing the air significantly. This allowed for an attempt to capture the comet behind the castle, despite the challenging location between two major sources of light pollution—Pardubice and Hradec Králové. On that particular evening, the comet aligned perfectly in a corridor between these two 'light domes,' appearing against a darker part of the sky," explains Petr Horálek, the photographer. The shoot was further complicated by dew and swarms of mosquitoes. „This image is not a simple 'single click,' but rather but a series of consecutively recorded images mathematically stacked on top of each other to minimize digital noise and reveal the delicate structures in the comet's tail," Horálek adds.

Kunětická hora, a reconstructed castle in Pardubice from the 15th century, is a frequent destination for tourists to observe the night sky, but also for photographers trying to record the castle with some interesting astronomical phenomenon. Petr Horálek himself has already experienced and photographed many astronomical events here. „As members of the astronomical circle of the Pardubice observatory, my friends and I observed, for example, the solar eclipse on May 31st, 2003 or the rare transit of Venus in front of the Sun on June 6th, 2012,“ recalls Horálek, who is also a native of Pardubice and therefore has a close relationship with the castle. Together with Josef Kujal from the Astronomical Society in Hradec Králové or Libor Hašple (both also in the past awarded the Astronomical Photo of the Day by NASA), they often photograph the rising or setting of the Moon behind the castle. „We have already recorded many images of the castle with an astronomical phenomenon here, I even recorded the comet NEOWISE from 2020. But this is the first time that Kunětická hora has been selected as NASA's Astronomical Image of the Day," concludes Horálek.

Comet 13P/Olbers, featured in the image, was discovered on March 6th, 1815, by the renowned German astronomer Heinrich Wilhelm Olbers (1758-1840). Although the comet is now moving away from Earth and gradually fading, it will remain relatively easy to observe for the next two weeks. Look for it low on the western to northwestern horizon in the constellation of the Big Dipper (shifting to the constellation of Coma Berenices around August 12) before 11 p.m. In a dark sky, far from city lights, observers should be able to spot it as a faint smudge through a small telescope, though a star map will be necessary for precise location. The comet orbits the Sun approximately every 70 years, meaning it won't be visible again until 2094. More information about the comet can be found in the June press release.

NASA's Astronomy Picture of the Day (APOD) (Astronomy Picture Of the Day) ) is a prestigious recognition awarded to the most captivating astronomical photo each day. Each image is carefully selected and accompanied by an insightful description written by editors Prof. Jerry Bonnell (University of Maryland) and Prof. Robert Nemiroff (Michigan Technological University), both of whom are NASA collaborators. APOD’s motto, "Discover the Universe," reflects its mission to highlight the wonders of the cosmos. Since its inception in 1995, APOD has become one of the most renowned platforms of its kind worldwide. The accompanying descriptions are translated into 23 languages, including Czech—a task undertaken by Josef Chlachula since 1999. APOD is followed by hundreds of millions of visitors daily on social media. For more information, visit the Czech Astronomical Society’s website.

Links to NASA's Astronomy Picture of the Day on August 1st, 2024:

Contact details:

Mgr. Petr Horálek

RNDr. Tomáš Gráf, Ph.D.

Bc. Lucie Dospivová

prof. RNDr. Zdeněk Stuchlík, CSc.