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The year 1604 in science and technology involved some significant events.
Astronomy
- 9 October – The supernova which becomes known as Kepler's Supernova (SN 1604) is first observed from northern Italy. From 17 October, Johannes Kepler begins a year's observation of it from Prague. , this is the last supernova to be observed in the Milky Way, and the last visible by the naked eye until 1987.
Exploration
- France begins settlement in French Guiana.
- Russian city of Tomsk founded in Siberia.
Medicine
- Johannes Kepler describes how the eye focuses light.
- Hieronymus Fabricius's De formato foetu (On fetus development), an embryology textbook.
- Joseph du Chesne's .
Physics
- Johannes Kepler specifies the law of rectilinear propagation for light waves.
Births
- 10 March – Johann Rudolf Glauber, German-born chemical engineer (died 1670)
Deaths
- 5 June – Thomas Muffet, English naturalist and physician (born 1553)
- before August – William Clowes, English surgeon (born c. 1543)
- approximate date – Juan Fernández, Spanish explorer (born c. 1536)