- Joseph Jérôme Le Français de Lalande (1732-1807)
- Born in France.
- He studied the Moon’s parallax.
- He produced the most comprehensive star catalogue of his time.
- Born in France.
- He established the nebular hypothesis for the creation of Earth, a theory that was accepted for most of the 19th century.
- Born in France.
- From the results of his study of the irregular movements of Uranus, he predicted the existence of an undiscovered planet (Neptune) and calculated where it would be.
- Born in Russia.
- In his study of Venus, he discovered that the planet is surrounded by a dense atmosphere.
- He supported the Copernican system, while most Russian astronomers did not.
- He was a pioneer in the kinetic theory of gases.
- He investigated aurora and electrical phenomena.
- Born in USA.
- He had an observatory built in Arizona.
- He believed that there were irrigation canals on Mars.
- His work led to the discovery of Pluto after his death.
Pierre Laplace (1749-1827)
Urbain Jean Joseph Leverrier (1811-1877)
Mikhail Lomonosov (1711-1765)
Percy Lowell (1855-1916)