Science & Discovery in the 4th century BC

12 sourced entries, 389 BCE to 320 BCE, oldest first. Also see Science & Discovery across every century or everything else in the 4th century BC.

• 389 BCEThis is the latest possible date for the compilation of the historical text Zuo Zhuan, attributed to a blind historian known as Zuo Qiuming.source
• 385 BCEDemocritus announces that the Milky Way is composed of many stars.source
• 383 BCEThe 19 year lunar cycle is introduced into the Babylonian calendar.source
• 371 BCEIt is suggested that the original comet associated with the Kreutz Sungrazers family of comets passes perihelion at this time. It is thought to have been observed by Aristotle and Ephorus during this year.source
• 370 BCEEudoxus of Cnidus develops the method of exhaustion for mathematically determining the area under a curve.source
• 364 BCEThe Chinese astronomer Gan De from the State of Qi reportedly discovers the moon Ganymede, belonging to Jupiter, and makes the earliest known sunspot observations.source
• 350 BCEAristotle argues for a spherical Earth using lunar eclipses and other observations. Also he discusses logical reasoning in Organon.source
• 350 BCEPlato proposes a geocentric model of the universe with the stars rotating on a fixed celestial sphere.source
• 344 BCEThe Greek philosopher and scientist, Aristotle, travels from Assus to Lesbos to study natural history, especially marine biology.source
• 325 BCEThe first known reference to sugar cane appears in writings by Alexander the Great's admiral Nearchus, who writes of Indian reeds "that produce honey, although there are no bees".source
• 323 BCEAlexander's father-in-law Oxyartes rules Gandhara;source
• 320 BCETheophrastus begins the systematic study of botany.source