Johannes Hevelius

Johannes Hevelius , 1611-87, Polish astronomer, b. Danzig. From a finely equipped observatory in his house at Danzig, assisted by his wife Elizabeth, he made valuable observations of the moon's surface, discovered four comets, and collected data for his catalog of 1,564 stars. He recorded his pioneer study of lunar topography in Selenographia (1647), noted for excellent lunar maps. Many of the names given by him to the lunar mountains, craters, and other features are still used. He was one of the first to observe (1661) a transit of Mercury. He improved astronomical instruments but resisted the introduction of telescopic sights. His surname appears in various spellings, among them Hevel, Hewel, Hewelcke, and Höwelcke.

Hevelius, Johannes (1611–87)Germanastronomer, born in modern Poland (in German Johann Hewelcke, in Polish Jan Heweliusz). In the early 1640s he derived a reasonably accurate value for the Sun's rotation period, and described and named faculae. His Selenographia (1647) contains the first fairly detailed map of the Moon with named features, although few of his names survive. He also discovered the Moon's libration in longitude. In the 1650s he began an observational programme that resulted in an atlas, Firmamentum Sobiescianum sive Uranographia, in which he introduced some new constellations, and an associated catalogue of 1564 stars, both published posthumously in 1690 by his second wife and assistant Elizabeth Hevelius, née Korpman (c.1646/7–c.1693). Hevelius was the last major astronomer to make positional measurements with naked-eye sighting instruments.