The article presents the history of Polish basic astronomical vocabulary on the Slavic background. There are twelve selected notions described: sky, sun, moon, new moon, full moon, quarter moon, star, planet, eclipse, horizon, comet and meteor. The majority of Polish contemporary basic astronomical vocabulary is already attested to in Old Polish (like 'niebo', 'slonce', 'ksiezyc', 'now', 'gwiazda', 'planeta', 'zacmienie'). The words 'pelnia', 'kwadra', 'horyzont' and 'kometa' appeared firstly in the 16th cent. The lexeme 'meteor' in the current astronomical meaning is attested to in the 19th cent. We deal with the numerous synonyms of contemporary astronomical terms in the history of Polish language. Some of them, like 'firmament', 'sklepienie niebieskie' and 'widnokrag', are still used, others disappeared irretrievably, for example 'obezrok', 'ziemiokres' and 'poziom' (all mean 'horizon'), some are preserved only in dialects, like 'miotla' (comet) and 'miesiac' (moon). It is worth noticing, that some of them - attested to already in Old Polish are for the first time named astronomical notions, for example 'miotla' and 'obezrok'. It is known that the group of early attested native words stand out distinctly in the Slavic languages because the names of respective notions in this group correspond with each other very closely (sky, sun, star, eclipse). The contemporary Polish name of moon (ksiezyc) is an old neosemantism. On the contrary, the names of moon in other Slavic languages are inherited words (however, they are derived from two different bases). The names of planet, comet, horizon and meteor are mainly loanwords (internationalisms) in the Slavic languages today.