John Dee was educated at a school in Chelmsford in Essex, then entered St. John's College, Cambridge in 1542. He became a Fellow of St. John's College in 1545 and the next year became a Fellow of Trinity College, Cambridge. Henry VIII founded Trinity College, the largest of the Cambridge colleges, in 1546 and Dee became one of its first Fellows.
Dee then travelled on the Continent (1547-1551). In a number of visits he studied with Gemma Frisius and Gerardus Mercator at the University of Louvain. In 1551 Dee was offered an appointment as professor of mathematics in Paris but declined. He also declined a lectureship in mathematics at Oxford three years later.
Dee became astrologer to Queen Mary but was imprisoned for being a magician. He was released in 1555. He then found favour with Queen Elizabeth and cast horoscopes for her. He even selected the day for her coronation.
In 1570 Dee edited an edition of Euclid translated by Billingsley. Dee wrote a famous preface to this edition justifying the study of mathematics. In 1573 Dee wrote Parallacticae commentationis praxosque which gives trigonometric methods which might be applied to find the distance to 'Tycho (Brahe)'s supernova' of 1572.
Dee also wrote on calendar reform, on navigation, on geography and on astrology. Dee brought instruments of navigation back from the Continent when he returned in 1551. From 1555 he was a consultant to the Muscovy Company. The Muscovy Company was formed in 1555 by the navigator and explorer Sebastian Cabot together with a number of London merchants. It was granted a monopoly of Anglo-Russian trade and had as one of its aims the search for the Northeast Passage. Dee prepared nautical information, including charts for navigation in the polar regions, for the company during the next 32 years.
Later in his career Dee became interested in astrology and alchemy, and he gave up other work for this. The lack of reaction of others to his scientific work drove him in the direction of alchemy which he saw as a quick way to glory. Dee visited Poland and Bohemia (1583-89), giving displays of magic at the courts of princes.