Georg Joachim Rheticus facts for kids

Georg Joachim de Porris, also known as Rheticus (born February 16, 1514 – died December 4, 1574), was a very smart person from the past. He was a mathematician, an astronomer, and even made maps and medical tools. He is most famous for his special math tables called trigonometric tables. He was also the only student of the famous astronomer Nicolaus Copernicus. Rheticus helped Copernicus publish his amazing book, De revolutionibus orbium coelestium, which means On the Revolutions of the Heavenly Spheres. This book changed how people thought about the universe.

Why Rheticus Changed His Name

Rheticus was born in a town called Feldkirch in Austria. His parents, Georg Iserin and Thomasina de Porris, were quite wealthy. His father was a town doctor and a government official. Rheticus was taught by his father until he was 14 years old.

In 1528, his father faced serious trouble. As a result, his family lost their original last name. They then started using his mother's maiden name, de Porris. Later, when Georg Joachim was a student at the University of Wittenberg, he chose a new last name: Rheticus. This name came from "Rhaetia," which was the old Latin name for his home region. This region included parts of Austria, Switzerland, and Germany. Even today, a crater on the Moon and an asteroid are named Rhaeticus after him!

How Rheticus Got His Start

After Rheticus's father passed away, a doctor named Achilles Gasser helped Rheticus continue his studies. He even gave Rheticus a letter to introduce him to Philipp Melanchthon. Melanchthon was a very important teacher and religious leader. He helped set up many new universities in Germany during the Protestant Reformation.

Melanchthon became a big supporter of Rheticus. He likely helped Rheticus get a teaching job at the University of Wittenberg. Rheticus studied in Feldkirch, Zürich, and Wittenberg. He earned his master's degree in 1536. After that, Melanchthon made him a professor of math and astronomy at Wittenberg University.

Two years later, Melanchthon arranged for Rheticus to take a two-year break. This break was so Rheticus could study with other famous astronomers. In 1538, he traveled to Nuremberg. There, he met other mathematicians and a book publisher named Johannes Petreius. It was probably in Nuremberg that Rheticus first heard about Copernicus. He decided he had to meet him.

Meeting Copernicus and Changing the World

Geocentric (upper) and Heliocentric (lower) views of the Solar System.

In May 1539, Rheticus arrived in Frombork, Poland. He spent two years living and working with Nicolaus Copernicus. Copernicus had been working on his big book for a long time. However, he hadn't published it yet. He was worried about how people would react to his ideas.

Rheticus convinced Copernicus to let him write a short summary of his research. This summary was called Narratio Prima (First Report). It was published in 1540. People loved it! It was seen as the best way to understand Copernicus's work. Because of its success, Copernicus finally agreed to let Rheticus help him publish his full book.

Rheticus used his connections to make sure the book got published. It was thanks to this meeting that Copernicus's amazing idea, the heliocentric theory, finally came out. This theory said that the Earth and other planets orbit the Sun, not the other way around. This idea was not fully accepted for many years.

While in Poland, Rheticus also visited Copernicus's friend, Tiedemann Giese. Giese was a bishop who also encouraged Copernicus to publish his work. Rheticus also made maps and instruments during his travels. He even made a special tool for Duke Albert of Prussia to figure out sunrise times. This helped him get a recommendation for Copernicus's book to be published.

Rheticus returned to the University of Wittenberg in 1541. In 1542, he went to Nuremberg to help supervise the printing of De revolutionibus. He even added his own tables of trigonometric functions to the book. These tables helped support Copernicus's ideas. However, Rheticus had to leave to take a new job. Another person, Andreas Osiander, took over the printing. Osiander added an introduction that said Copernicus's ideas were just a theory, not facts. Rheticus was very upset about this. Copernicus's main work was finally published shortly before he died in 1543.

Rheticus also wrote about how Copernicus's ideas could fit with religious beliefs. He suggested that the Bible focuses on what's important for salvation. It doesn't always talk about scientific details like how the Earth moves. He believed the Bible used language that everyone could understand.

It borrows a kind of discourse, a habit of speech, and a method of teaching from popular usage.

Rheticus's Later Life and Work

Even though he is famous for helping Copernicus, Rheticus did many other things. After leaving Wittenberg, he studied medicine at the University of Prague. He then moved to Kraków, Poland, in 1554. He worked there as a doctor for 20 years.

While in Kraków, he kept working on math and astronomy. He continued to create his detailed tables of trigonometric functions. He received money from Emperor Maximilian II to help with this work. Rheticus also made a special staff for King Sigismund II of Poland. Later, he moved to Košice in Hungary, where he passed away.

Rheticus and Trigonometry

Rheticus loved studying triangles, which is the main part of trigonometry. In 1542, he published the trigonometry sections from Copernicus's book separately. This book was called De lateribus et angulis triangulorum (On the Sides and Angles of Triangles).

In 1551, Rheticus published Canon of the Science of Triangles. This was the first time anyone published tables for all six trigonometric functions. This small book was meant to be an introduction to his biggest work. This big work was a complete set of tables for measuring angles in astronomy.

When Rheticus died, his big work, Science of Triangles, was not finished. But just like he helped Copernicus, Rheticus had a student named Valentinus Otho. Otho was determined to finish his teacher's work. He spent years calculating about 100,000 math ratios. These calculations were very precise, going to at least ten decimal places. When it was finished in 1596, the book was nearly 1,500 pages long! These tables were so accurate that they were used in astronomy until the early 1900s.

Works by Rheticus

• Narratio prima de libris revolutionum Copernici (1540) - This was his "First Report" about Copernicus's work.
• Tabula chorographica auff Preussen und etliche umbliegende lender (1541) - A map of Prussia and nearby lands.
• De lateribus et angulis triangulorum (with Copernicus; 1542) - About the sides and angles of triangles.
• Ephemerides novae (1550) - Astronomical tables.
• Canon doctrinae triangulorum (1551) - His book on the "Science of Triangles."
• Epistolae de Terrae Motu (published after his death) - A letter about the Earth's motion.

Images for kids

• 

  Frontpage of Canon Doctrinae Triangulorum