First Polish comet – C/1925 G1 (Orkisz)

Illustrated: Lucjan Orkisz poses at the telescope shortly after discovering the comet. The frame comes from the educational film on astronomy ‘The discovery of Orkisz's comet’, filmed by Szczęsny Mysłowicz in 1925. Source: National Digital Archive/ Jagiellonian University in Cracow.

It was a world-class astronomical achievement. While comets had been observed and discovered on Polish lands before, these early discoveries were not officially documented. Orkisz's comet was the first to be formally listed by the International Astronomical Union as discovered by a Polish astronomer – in Poland, which became independent only a few years earlier. The importance of this discovery is evidenced by the congratulatory letters received from observatories and the fact that shortly afterwards a popular science film entitled The Discovery of Orkisz's Comet was made to promote the scientific work of the Cracovian astronomer. Additionally, in the 19th and early 20th centuries, observations of comets were considered of great importance. Discoveries of new objects of this type raised the prestige of every astronomer and observatory.

During his studies at the end of 1920, Lucjan Orkisz started working at the Jagiellonian University's Astronomical Observatory, which was then located in the Collegium Śniadeckiego in Kopernika Street. Four years later he was entrusted with the duties of head of the mountain observatory station on Łysina (904 m above sea level) near Myślenice, newly established by Professor Tadeusz Banachiewicz, the current director of our observatory. In the provisional mountain observatory located in the Lubomirski family forester's lodge, there was no electricity or radio, it was cold and lonely, but the clear mountain air made it possible to carry out much more accurate observations of the sky than from Cracow, which was already brightly lit in those years. During his duty at the station, Orkisz was engaged, among other things, in searching for comets using a Merz telescope with a lens diameter of 11.5 cm. Finding comets was not a straightforward job at that time. It required many hours of tedious scanning of the sky. Such observations often had to be made also in the morning. However, for Lucjan Orkisz, the effort paid off rather quickly.

When discovered, the newly discovered comet was not discernible to the naked eye. At the time of its maximum brightness, which it reached in mid-May 1925, its magnitude was about 6.9^m. The object continued to be observed until May 1926 in more than 40 observatories around the world.

Orkisz later studied the motion parameters and orbit of his comet for years, eventually making it the basis of his doctoral thesis, entitled Die definitive Bahn des Kometen 1925 I (Orkisz) (Definitive orbit of the comet 1925 I (Orkisz)), defended in 1931. The comet was given the designation C/1925 G1, where the letter ‘C’ refers to the type of comet: it is a single-appearance comet, i.e. a comet that has only appeared in the vicinity of the Sun once and in all probability will not return to its neighbourhood again. However, it should be remembered that observational methods from a century ago were sometimes subject to significant errors. Today, C/1925 G1 (Orkisz) is generally considered to be a comet of hyperbolic orbit, that is, being an open conic curve -- as opposed to comets in elliptical orbits, orbiting the Sun in a closed manner and therefore returning regularly to its vicinity with a shorter or longer period. Previously, however, there have also been hypotheses that C/1925 G1 can be a returning comet in an elliptical orbit with a very long period, of the order of thousands years. Interestingly, if its orbit is nonetheless hyperbolic, this famous Polish comet is also theoretically a candidate for a so-called extrasolar comet, originating from a star system other than our own.