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.