1609 in science
- July 26 – English scientist Thomas Harriot becomes the first to draw an astronomical object after viewing it through a telescope: he draws a map of the Moon, preceding Galileo by several months.
- Johannes Kepler publishes Astronomia nova, containing his first two laws of planetary motion.
- Charles Butler publishes The Feminine Monarchie, or, A Treatise Concerning Bees.
- April 4 – Henry Hudson sets out from Amsterdam in the Halve Maen.
- Louise Bourgeois Boursier publishes Diverse Observations on Sterility; Loss of the Ovum after Fecundation, Fecundity and Childbirth; Diseases of Women and of Newborn Infants in Paris, the first book on obstetrics written by a woman.
- Jacques Guillemeau publishes De l'heureux accouchement des femmes in which he describes a method of assisted breech delivery.
- June 29 – Pierre Paul Riquet, French engineer and canal builder (died 1680)
- October 8 – John Clarke, English physician (died 1676)
- March 26 – John Dee, English alchemist, astrologer and mathematician (born 1527)
- April 4 – Carolus Clusius, Flemish botanist (born 1525)
- August 4 - Joseph Duchesne, French physician and alchemist (born c.1544)
- December – Oswald Croll, German iatrochemist (born c. 1563)
- André du Laurens, French physician and gerontologist (born 1558)
- McGourty, Christine (2009-01-14). "'English Galileo' maps on display". BBC News. Retrieved 2012-07-04.
- "Thomas Harriot's Moon Drawings". The Galileo Project. 1995. Retrieved 2012-07-04.
- Hunter, Douglas (2009). Half Moon: Henry Hudson and the voyage that redrew the map of the New World. London: Bloomsbury Press. p. 11. ISBN 1-59691-680-X.
- Nevius, Michelle; James (2008-09-08). "New York's many 9/11 anniversaries: the Staten Island Peace Conference". Inside the Apple: A Streetwise History of New York City. Retrieved 2011-10-25.
- Juet, Robert (1625). "Juet's Journal of Hudson's 1609 Voyage". In Purchas, Samuel. Hakluytus Posthumus, or Purchas his Pilgrimes. 4.
- Anzovin, Steven (2000). Famous First Facts. H. W. Wilson Co. ISBN 0-8242-0958-3.
- Roberts, R. Julian (2004). "Dee, John (1527–1609)". Oxford Dictionary of National Biography. Oxford University Press. doi:10.1093/ref:odnb/7418. Retrieved 2011-04-18. (subscription or UK public library membership required)