Ptolemy (#110)

Background

Claudius Ptolemy was a Roman citizen born around the year AD 90, and he lived in Egypt under Roman rule. Ethnically, Ptolemy was Greek, and all of Ptolemy's works were written in Ancient Greek.

Life and Work

One of Ptolemy's most important surviving works is the Almagest, which is the only surviving comprehensive ancient document on astronomy. Using Babylonian astronomical data and Greek mathematics, Ptolemy created tables to predict the positions of planets in the future and the past. Also, Ptolemy created a star catalog, including forty-eight constellations. One of the key problems in Ptolemy's work was the idea of a geocentric universe, where everything revolved around the Earth. He explained the back-and-forth movement of planets by stating that the planets had sub-orbits within their larger orbit around the Earth. Because it was one of the few astronomical documents to survive into the Middle Ages, it was considered the law on astronomy during that time, and his geocentric ideas were not disproved until Nicolaus Copernicus wrote De revolutionibus in 1543. Ptolemy also wrote Planetary Hypotheses, which used his planetary model to compute the dimensions of the Solar System. Ptolemy also wrote Geographia, a work which mapped out the known world. His maps goes from Cape Verdes in the West to the middle of china in the East, and is fairly accurate considering the time this map was made. Ptolemy knew that his map only covered a quarter of the globe, but his map was still used widely up through the Middle ages. Ptolemy also wrote on astrology, where he predicted the future of people while also taking into account differences in race, country, and upbringing. Ptolemy is also remembered through his works Harmonics, where he argued that musical intervals should be based on mathematical ratios, and Optics, in which Ptolemy wrote on the properties of light, reflection, refraction, and color.

The End

Ptolemy died around the year AD 168. Ptolemy is listed on this list before Copernicus because not only did he work in more fields, but also because Ptolemy's works helped for the scientific basis for Europe in the Middle Ages, where they turned into a legend, calling him Ptolemy, King of Alexandria. Copernicus wasn't called the King of  Krakow. Also, Ptolemy has two craters (one on the Moon and one on Mars) named after him.

Nicolaus Copernicus (#115)

Young Life and College

Nicolaus Copernicus was born on February 19, 1473 in Poland from two merchant families. He was the youngest of four children. At first, while being supported by his uncle, Copernicus studied at the University of Krakow in 1491, where he attained the mathematical and astronomical skill for his later achievements. He also was able to study the natural-science writings of Aristotle and Averroes while studying in Krakow.  In 1495, Copernicus left Krakow because of his uncle Watzenrode wanted him to study law in Italy, hoping for Copernicus to join the Warmia canonry, which Watzenrode was the Prince-Bishop of. In 1497, Copernicus registered in the Bologna University of Jurists. In Bologna, Copernicus studied law, the humanities, and astronomy. He became the assistant of astronomer Domenci Maria Novara da Ferrara. Under Ferrara, he began to find peculiarities in Ptolemy's geocentric universe theory based on observations of the star Aldebaran. Copernicus moved to Rome in 1500, where he continued his astronomical studies. Copernicus also went to the University of Padua, where he studied medicine, which include astrology. Over his education, Copernicus learned Latin, Greek, German, and Italian along with his native Polish.

Work

Copernicus, after his studies, became his uncle's secretary and physician in Heilsberg. He took part in almost all of his uncles political, administrative, and economic activities. This is where Copernicus began work on his heliocentric theory. Copernicus also made trips on business from his uncle. In 1510, Copernicus ended work for his uncle, and worked as a translator of Greek and Latin texts. In 1514, the first outline of the heliocentric world was written. Throughout his life, Copernicus worked as a assistant to politicians and religious leaders while continuing to study astronomy. By 1532, his manuscript on heliocentrism was basically complete, but he resisted publishing due to fears of scorn. His book, De revolutionibus orbium coelestium, was published under Georg Rheticus, who had published other works of Copernicus. Along with Andreas Osiander, Rheticus worked to have the book published in 1542.

The End

Legend has it that the first copy of De revolutionibus ever printed was placed in Copernicus's hand on May 24, 1543, the day that Copernicus died. Copernicus makes our list for being one of the few people in the world who changed the world's mind. Before him, the common theory was that everything orbited the Earth. Copernicus proved them all wrong. He changed the way people looked at the world, and not many people can do that.