The year 1509 in science and technology included many events, some of which are listed here.

Exploration

• September 11 – Diogo Lopes de Sequeira reaches Malacca, having crossed the Gulf of Bengal.

Geology

• September 10 – Constantinople earthquake.^[1]

Mathematics

• June 11 – Luca Pacioli's De divina proportione, concerning the golden ratio, is published in Venice, with illustrations by Leonardo da Vinci.

Births

• Bernardino Telesio, Italian philosopher and natural scientist (died 1588)
• possible date – Guillaume Le Testu, French privateer, explorer and cartographer (k. 1573)

Deaths

• Juan de la Cosa, Spanish explorer and cartographer (b. c. 1460)