1821 in science

The year 1821 in science and technology involved some significant events, listed below.

Astronomy

* Comet Encke is the second comet to be discovered to have a periodic orbit, after Comet Halley.
* Alexis Bouvard detects irregularities in the orbit of Uranus.

Exploration

* William Edward Parry starts his second voyage to find the Northwest Passage.

Geology

* Ignatz Venetz proposes his ice age theory.
* Pierre Berthier discovers bauxite.
* Mary Anning finds the first ever plesiosaur fossil at Lyme Regis.

Mathematics

* Augustin Louis Cauchy gives the first complete presentation of calculus using limits.

Paleontology

* William Buckland finds the remains of a hyena's den in Yorkshire, containing the bones of lions, elephants and rhinoceros.

Physics

* Michael Faraday discovers electromagnetic rotation.
* Thomas Johann Seebeck discovers the thermoelectric effect.
* Augustin Fresnel shows that light is made up of a traverse wave motion.

Awards

* Copley Medal: Edward Sabine; John Herschel

Births

* May 16 - Pafnuty Chebyshev (d. 1894), mathematician.
* August 16 - Arthur Cayley (d. 1895), mathematician.
* August 31 - Hermann von Helmholtz (d. 1894), physicist.
* October 13 - Rudolf Virchow (d. 1902), biologist.
* November 18 - Franz Bronnow (d. 1891), astronomer.

Deaths

* April 20 - Franz Karl Achard (b. 1753), chemist.