Gustav Gruss was born into the family of a court clerk in Jičín in 1854. He graduated from the Jičín grammar school and later went on to study the natural sciences at what was then the Faculty of Arts at Charles Ferdinand Universitys. There, his main focuses of interest were physics and astronomy; he was a pupil of Ernst Mach and, while he was still a student, became Karl Hornstein’s assistant at the observatory in the naKlementinum. After completing his studies he worked briefly in government administration and as a secondary school teachers. However, he eventually returned to the Klementinum and later to the university. He even headed the observatory for a short time and, after the death of the prominent astronomer August Seydler, was appointed professor in his place and actually became the head of the university astronomical institute. He started to focus his attention on variable stars and spectroscopy and de facto thus became the founder of Czech astrophysics. In addition to this, he studied theoretical astronomy and explored lunar eclipses and observed comets and other bodies in the Solar System. He helped to calculate the orbits of celestial bodies and was part of international research into the fluctuations of the position of the Earth's poles. His interests also touched upon meteorology, when he studied the impact that celestial bodies have on the weather on Earth. Besides his scientific work, he also played an important role in popularizing the subject. He was one of the first popularisers of astronomy who succeeded in attracting a great many enthusiasts to astronomy. His book Z říše hvězd [From the Realm of the Stars] was for a long time the only comprehensive and scientifically sophisticated popular publication in the field. The professional journal published by the Czech Astronomical Society still bears this name today. Planet no. 6516, discovered in 1988 by Antonín Mrkos, is named in honour of Gustav Gruss.

Keywords: astronomy; physics; astronomy; astrophysics; Klementinum; Astronomical Institute