Short answers, pulled from the story.
Pedro Nunes was a Portuguese mathematician, cosmographer, and professor who lived from 1502 to 1578. He is best known for being the first to describe the loxodrome (rhumb line) and for inventing the nonius, a precision measuring device from which the Vernier scale was later derived.
A loxodrome, or rhumb line, is the spiral path a ship traces when it holds a constant compass bearing relative to the meridians rather than following the shortest arc across the Earth's surface. Pedro Nunes was the first to understand and describe this phenomenon mathematically, recognizing that a steady course does not equal a straight path on a globe.
The nonius was a measuring device Nunes invented to improve the accuracy of instruments like the quadrant. It used concentric circles, each divided into one fewer section than the one outside it. Pierre Vernier simplified the principle in 1631 into two scales, one fixed and one movable; Vernier himself called his invention a perfected nonius, and in Swedish the Vernier scale is still named nonieskala in Nunes' honor.
Nunes taught at the University of Lisbon and later at the re-founded University of Coimbra, where he held the mathematics chair from 1537 until 1562. He was appointed Royal Cosmographer in 1529 and Chief Royal Cosmographer in 1547, a title he held until his death. He also tutored members of the Portuguese royal family, including the future king Sebastian.
Nunes determined both which day of the year has the shortest twilight for any given location and the exact duration of that twilight. More than a century later, Johann and Jakob Bernoulli tackled the same problem independently and could find the day but failed to calculate its duration. Nunes solved both parts without the differential calculus that later mathematicians relied on.
Pedro Nunes is commemorated by the Escola Secundária de Pedro Nunes in Lisbon, founded in 1906, by the Instituto Pedro Nunes in Coimbra, and by asteroid 5313 Nunes. His image appeared on 100 escudos coins, and TAP Air Portugal named an Airbus A330-202 after him, registered CS-TOP.