1621 in science

The year 1621 in science and technology involved some significant events.

Astronomy

 * Johann Schreck (1576–1630), also known as Johannes Schreck, Terrenz or Terrentius, introduces the telescope to China.

Botany

 * The University of Oxford Botanic Garden, the oldest botanical garden in Great Britain, is founded as a physic garden by Henry Danvers, 1st Earl of Danby.

Medicine

 * Robert Burton publishes his treatise The Anatomy of Melancholy.

Physics

 * Willebrord Snellius formulates Snell's law on refraction.

Technology

 * A simple microscope is developed.
 * Cornelius Vermuyden begins reclamation of Canvey Island in England.

Births

 * January 27 – Thomas Willis, English physician who contributes to knowledge of the nervous and cardiovascular systems (died 1675)

Deaths

 * July 2 – Thomas Harriot, English ethnographer, astronomer and mathematician (born c. 1560)
 * September 1 – Bahāʾ al-dīn al-ʿĀmilī, Arab philosopher and astronomer (born 1547)
 * Jan Jesenius, Slovak physician (born 1566)