The Magnificent Observatory and Discoveries of Johannes Hevelius

Johannes Hevelius is one of the symbols of Gdansk, Poland. He is also one of the three great intellectuals, along with Fahrenheit and Schopenhauer, who were born in this city. During Hevelius’ life, his observatory was known as one of the most important centers for astronomy in Europe.

The Life and Loves of Johannes Hevelius

Johannes Hevelius, known in Poland as Jan Heweliusz, lived at the center of the city of Gdansk near the Baltic Sea. He grew up in a town that was full of different cultures, possibilities, and freedom of speech. Johannes was born on January 28, 1611 to Abraham and Kordula Hewelke. (The surname ‘Hewelke’ has been transformed many times and currently it's recognized as Hevelius.) The family were German-speaking Lutherans.

As a boy, Johannes studied at the gymnasium. While he was there, he was taught by the famous mathematician Peter Kruger. In 1630, Hevelius went on to study law at Leiden. After completing his studies, he traveled in France and England - where he met Pierre Gassendi, Marin Mersenne, and Athanasius Kircher.

Kruger's Azimuthal Quadrant, completed by Johannes Hevelius 1644. (Public Domain)

Johannes was lucky to meet two women who supported his scientific growth, and many protectors who believed in his talents. He met his is first wife, Katherine, after he returned to Gdansk. They were married on March 21, 1635. That same year, Hevelius became a member of the beer-brewing guild, which brought him wealth and a strong position in society. Unfortunately, Katherine died of an unknown disease in 1662.

A year later, Hevelius married a woman who became his greatest partner in his search for the unknown in the night sky - Elisabeth Hevelius née Koopmann. Elisabeth was the youngest daughter of a merchant family. Both of the women took great care of their husband and were loving and understanding wives.

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Elisabeth was only 16 years old when she married Hevelius, and she became his best friend. She also gave him four children and took care of all the daily chores, allowing Hevelius to work on his research as much as possible. After Johannes's death she even published two of his books. She also completed some of his unfinished manuscripts and became the first female astronomer in her part of the world.

Hevelius and his wife Elisabeth making observations, 1673. (Public Domain)

The Observatory, a Scientific Crown of the City

The observatory of Johannes Hevelius was known as Stellaeburgum – Starenburg, which means “the Star Castle” (in Polish “Gwiezdny Zamek”). It was located on the roof of three connected houses belonging to Hevelius on the corner of modern Korzenna Street. All of the construction was planned by the astronomer.

 When he had the observatory built in 1641, it was equipped with splendid instruments - including a large Keplerian telescope with a 46 m (150 ft) focal length. This was probably the longest "tubed" telescope created before the area of the tubeless aerial telescope.

Fig. AA from Machinae coelestis, 1673, by Johannes Hevelius. (1611-1687) (Public Domain)

With his impressive analytical feats, Hevelius became famous amongst the royals and gained the support of many of the most important people of his times. For example, Hevelius enjoyed the patronage of the King of Poland, Jan Kazimierz, in 1659. His private observatory was also visited on January 29, 1660 by the Polish Queen, Marie Louise Gonzaga. He received financial support from the court of the King of France, Louis XIV as well.

The Polish King John III Sobieski regularly visited Hevelius between 1677 and 1683. He was so impressed by the man and his work that he released the astronomer from paying taxes connected with brewing, and allowed him to sell beer outside the city limits. This friendship was crowned with the naming of the constellation Scutum Sobiescianum (Sobieski's Shield), in honor of the victory of the forces led by the Polish King at the Battle of Vienna.

The Battle of Vienna. (Public Domain)

Thus, the observatory became one of the most important parts of the city for a time. Young aspirants of the sciences arrived there from all over Europe to learn from the master of Gdansk.

Books and Inventions by Hevelius

Hevelius was able to focus on his career and passions in the peaceful environment his wife created for him. He began to study astronomy from about 1639. He also took a leading role in municipal administration, and became a town councilor in 1651. With time, he gained a reputation as an astronomer who was "the founder of lunar topography," and discovered ten new constellations. (Seven of these constellations are still recognized by astronomers.) When he didn't research the sky, he tried to invent new tools and instruments to make his observations and analysis more successful. One of his inventions is the pendulum clock.

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In 1664, Hevelius became a member of the famous Royal Society in London. 15 years later, he was visited by a young Englishman named Edmond Halley. The society wanted Halley to persuade Hevelius to allow them to use his measurements for modern telescopes. Hevelius demonstrated his methods to Halley and their discussions influenced the future researcher of Halley's Comet.

Hevelius' map of the Moon. (Public Domain)

Hevelius observed sunspots, discovered the Moon's libration in longitude, and identified four comets - in 1652, 1661, 1672, and 1677. He published several monumental books, including, the most famous, Selenographia (1647), but also De nativa Saturni facie ejusque varis Phasibus (1656), Prodromus cometicus (1665), and, the most criticized, Cometographia (1668). He was also the author of Historiola Mirae (1662), in which he named and described the periodic variable star Omicron Ceti Mira.

In 1673 and 1679, Hevelius published a book titled Machina coelestis, which is an extremely important work by the astronomer as it contains a description of his instruments and inventions. He also described his observation methods in this text. The last book he wrote was Annus climactericus, sive rerum uranicarum observationum annus quadragesimus nonus, which was published in 1685.

A Dear Astronomer of Gdańsk

The great observatory of Hevelius was destroyed by fire on September 26, 1679. The fire ruined his books, instruments, and personal items. After this tragedy, Hevelius described the catastrophe in the preface to his Annus climactericus (1685). This unlucky event shocked and upset Hevelius.

When he regained himself, he tried to repair the damaged objects, recreate old notes, and summarize everything that he remembered from his past work. He then prepared his observatory to observe a comet in December 1680. He later named a new constellation Sextans in memory of his lost instruments.

Star map showing Sextans. (CC BY 3.0)

Johannes Hevelius passed away on his 76th birthday, January 28, 1687. He was buried in St Catherine's Church, near his observatory. Nowadays, Johannes Hevelius is a symbol of the city of Gdansk. The site where his observatory was located was destroyed during World War II, but the city is full of other places that are dedicated to his memory. Perhaps the most important one being a monument located on the site of his old brewery. In this monument, master Hevelius is shown sitting on a chair and looking into the sky - as he used to do it in his observatory near Korzenna Street.

Monument to Jan Heweliusz in modern Gdańsk (Pplecke/CC BY-SA 3.0)

Featured Image: Johannes Hevelius, Prodromus Astronomia, volume III. (Public Domain), Johannes Hevelius, by Daniel Schultz. (Public Domain)

By Natalia Klimczak