1665 in science

The year 1665 in science and technology involved some significant events.

Events

Summer – Isaac Newton graduates from the University of Cambridge which is then closed as a precaution against bubonic plague so he retires to his birthplace at Woolsthorpe-by-Colsterworth to develop his theories on calculus, optics and the law of gravitation.

Giovanni Cassini discovered Jupiter's red spot was a permanent feature and used this to measure Jupiter's period of rotation as 9 hours 56 minutes.{{cite book |last=Hockey |first=Thomas |date=1998 |title=Galileo's Planet: Observing Jupiter Before Photography |url=https://books.google.com/books?id=FhstfdOsgwoC |publisher=CRC Press |page=26 |isbn=978-0750304481 |quote=Cassini's sighting of a 'permanent spot' in 1665 was the more important observation because the regular recurring passage across the jovian disc of this easily observed feature not only offered proof of Jupiter's rotation but allowed Cassini to calculate the first reliable rotation time for the planet: 9h 56min}}

Publication of the 'Atlas Maior' (Theatrum Orbis Terrarum) completed by Joan Blaeu in Amsterdam.

April 12 – First recorded victim of the 'Great Plague of London' (1665–66), the last major outbreak of bubonic plague in the British Isles.

September – Robert Hooke's Micrographia published, first applying the term 'cell' to plant tissue, which he discovered first in cork, then in living organisms, using a microscope.

Athanasius Kircher in Mundus Subterraneus (publication of which begins in Amsterdam) describes giant bones as those belonging to extinct races of humans.{{cite book|last=Palmer|first=Douglas|year=2005|title=Earth Time: exploring the deep past from Victorian England to the Grand Canyon|publisher=Wiley|location=Chichester|isbn=978-0-470-02221-4}}

January 5 – The Journal des sçavans begins publication in France, the first scientific journal.
March 6 – The Philosophical Transactions of the Royal Society of London begins publication in England under the editorship of Henry Oldenburg, the first scientific journal in English and the oldest to be continuously published.