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.
^Hockey, Thomas (1998). Galileo's Planet: Observing Jupiter Before Photography. CRC Press. p. 26. ISBN978-0750304481. 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
^Palmer, Douglas (2005). Earth Time: exploring the deep past from Victorian England to the Grand Canyon. Chichester: Wiley. ISBN978-0-470-02221-4.