An illustration in the star atlas of Johannes Hevelius, Firmamentum Sobiescianum sive Uranographia, Gdansk, 1690. (Linda Hall Library)

Johannes Hevelius was one of the 17th century's most respected and prolific astronomers. He studied sunspots, produced a lunar chart, discovered several comets, and produced an influential star atlas. He made his own precision instruments and wrote Machina coelestis about instrumentation, as well as other works. He was also an engraver and publisher.

Background and early life
Hevelius was born on January 28, 1611 in Danzig — now the Polish city of Gdansk. The family was German, and both parents came from well-off merchant families. Danzig was part of the Polish-Lithuanian Commonwealth, so Hevelius is now claimed both by Germans and Poles. There are various versions of his name, but I'll use Johannes Hevelius. This is the Latinized form, following the custom of educated people in those days.

Johannes was one of ten children, but the only son to survive beyond childhood. He was educated in Danzig, except for three years when the school was closed. In his final school years he studied with Peter Crueger who taught him astronomy, mathematics and astronomical instrument-making.

In 1630 Johannes went to the Netherlands to study law at the University of Leiden, but didn't take a degree. In 1631 he went traveling, meeting a number of prominent astronomers in London and Paris. He was planning to go on to Italy to meet Galileo, but as the son and heir, he was recalled to the family brewing business.

Business, family and astronomy in Danzig
Hevelius returned to Danzig in 1634, and the following year married Katherine Rebeschke, daughter of another wealthy merchant family. He worked in the family brewery to learn the business, and although we know him as an astronomer, he was also a successful businessman and prominent citizen of Danzig. During his life he would become an honorary magistrate, a town councillor and leader of the brewers' guild.

After five years at home Hevelius again felt the pull of astronomy. He and his wife owned a few properties next to each other, and in 1640 he started his observatory by building in an upper story of one of them. The observatory extended over three rooftops and had top class astronomical instruments built by Hevelius himself, including a 150-foot telescope. It was visited not only by fellow astronomers, but by the Polish king who supported his work.

Second marriage
In 1662 Katherine died, and the following year Johannes married 16-year-old Elisabetha Koopman. It may sound like a recipe for disaster for an old fool, but not so. Elisabetha was an extraordinary young woman, intelligent, well-educated and with a passion for astronomy as great as that of Johannes. The marriage would last nearly a quarter of a century, and produce four children and a superb astronomical partnership.

Elisabetha eagerly learned about the stars and the instruments. She helped Johannes manage the observatory, and they often observed together. The French astronomer Arago described her as “the first woman, to my knowledge, who was not frightened to face the fatigue of making astronomical observations and calculations.” Elisabetha Hevelius is often considered the first female astronomer.

Dispute with Hooke
Although the astronomical telescope had come into use before he was born, and Hevelius did use a telescope for some purposes, he preferred to measure star positions without it. Hevelius was the last astronomer to produce major work without lenses.

In 1664 Hevelius was elected to Britain's Royal Society. And in 1673 fellow member Robert Hooke took exception to Hevelius's dedication to unaided-eye observation. Hooke was a man of many talents, but tact wasn't one of them, and his argument in favor of lenses was inflammatory and personal. Although Hevelius remained polite, he was upset and not about to change the way he observed.

In 1679, on behalf of the Royal Society, Edmond Halley went to Danzig. Although only 22, he was a seasoned observer and had produced a catalog of southern hemisphere stars based on his observations on St Helena. And unlike Hooke, he had a knack for getting along with people. Halley took with him the quadrant with telescopic sights which he had used on St Helena.

Hevelius was happy to have his observing tested, as he was quite proud of his equipment and his eyesight. Halley concluded that Hevelius's accuracy with his instruments was equal to that of a telescope.

Loss, but not defeat
Later in 1679 a fire — probably arson — destroyed the observatory. They lost horses in the stable block, all of the instruments, the printing office, and much — but not all — of Hevelius's manuscripts.

Although Hevelius was 68 and the loss had undermined his health, he didn't give up. He started rebuilding, and replaced the instruments, though the new ones weren't as good as the originals. The manuscripts for the star catalog and atlas had been saved, but needed to be edited and prepared for printing.

Sadly, Hevelius died on his 76th birthday in 1687 with his atlas incomplete. He had invented ten constellations, and there were 1564 stars located with great accuracy. For the southern sky, he used Halley's star positions. It would be the first major new star atlas since Johann Bayer's in 1603.

Elisabetha Hevelius
Nonetheless the atlas Firmamentum Sobiescianum and its accompanying catalog were published. Elisabetha had taken over the editing and overseen the printing. Seven of Hevelius's constellations are still in use.

Elisabetha died in December 1693, just three years after publishing these final works, and was buried in the same tomb as Johannes.