1619 in science

Astronomy

• Publication of Johannes Kepler's third law of planetary motion in his Harmonices Mundi. He also recognises the duality of convex polyhedra.
• Publication of the Jesuit Giuseppe Biancani's Sphaera mundi, seu cosmographia demonstrativa, ac facili methodo tradita in Bologna.

  Biochemistry

• Lactose is discovered by Fabriccio Bartoletti; the word lactose comes from the Latin word lac which means "milk".

  Exploration

• In North America, the Churchill River is discovered by Danish explorer Jens Munk, and it will be used for over 100 years as a trading route of the Hudson's Bay Company from their fort at its mouth to the interior.
• Frederick de Houtman and Jans van Edel discover the Houtman Abrolhos islands.

  Medicine

• Dermod O'Meara's text on genetic disorders, De Moribus: Pathologia Haereditaria Generalis is published in Dublin, the first medical text published in Ireland.

  Metallurgy

• Sir Basil Brooke produces steel using a reverbatory furnace in Coalbrookdale, England.

  Births

• probable date – Daniel Whistler, English physician

  Deaths

• May 21 – Hieronymus Fabricius, Italian anatomist and embryologist
• September – Hans Lippershey, Dutch lensmaker, credited with inventing the telescope in 1608
• Olivier de Serres, French soil scientist
• Caterina Vitale, Maltese chemist