ENIn 1777–1778, astronomer Andrew Strzecki (Polish Andrzej Strzecki, Lithuanian Andrius Streckis, 1737–1797) from Vilnius went on a scientific journey to Western Europe, visiting Vienna, Paris, London, and some other cities. This article aims to investigate and describe the motives, chronology, itinerary, and outcomes of this journey, and to evaluate the importance of this event for the science history of Vilnius and Europe. The research is based on an analysis of original correspondence, with some of the letters mentioned in print for the first time. The narrative method was applied to create a coherent storyline from the incomplete data found in various manuscripts and other sources. The research sheds light on previously obscure details of Early Modern European scientific communication, among them, the connections between astronomers of Vilnius and Vienna. The article also mentions the circumstances of the events, which were essential in the history of Vilnius University: the election of Marcin Poczobut Odlianicki (Lithuanian Martynas Odlianickis Počobutas, 1726–1810) as a member correspondent of the Paris Academy of Sciences and international recognition of the constellation he introduced, Taurus Poniatovii. The article confirms that the social and scientific ties of astronomers in Vilnius were much broader than what is usually described and included their close personal relationships with some of the first-rated scholars of the era, such as Rugerius Boskovich, Nevil Maskelyne, and Benjamin Franklin. Keywords: Andrius Streckis (Andrzej Strzecki), British Royal Society, Greenwich Observatory, History of astronomy, international science communication, L’Académie des Sciences, solar eclipses, Vilnius University Observatory. [From the publication]