The world's first liquid-fueled rocket was launched.
Astronomer Edwin Hubble formally announced the existence of other galactic systems at a meeting of the American Astronomical Society.
The New York Times published Edwin Hubble's discovery that the Andromeda 'nebula' is actually a galaxy.
Mars had a 'close encounter' with Earth at 34.8 million miles apart.
Carl Gustav Witt discovered the first near-Earth asteroid, 433 Eros.
American Astronomer William Henry Pickering discovered Phoebe, one of Saturn's moons.
American astronomer Edward Emerson Barnard discovered Jupiter's fifth moon.
Asteroid 323 Brucia became the first asteroid discovered using photography.
Asaph Hall discovered Mars' second moon, called Phobos.
One of Mars' moons, 'Deimos,' was discovered by an American astronomer, Asaph Hall.
Alvan Graham Clark discovered the white dwarf star Sirius B.
Urbain Le Verrier announces the discovery of the planet Vulcan.
George Mary Searle discovered the asteroid 55 Pandora.
Frederick Langenheim took the first photo of a solar eclipse.
British astronomer William Lassell discovered two of Uranus' moons, Ariel and Umbriel.
British astronomer William Lassell discovered Neptune's largest moon, Triton.
The Moon was photographed for the first time.
German Astronomer Karl Ludwig Harding discovered the 3 Juno asteroid in the Asteroid Belt.
The dwarf planet Ceres was discovered by an Italian monk called Giuseppe Piazzi.
German-British astronomer William Herschel discovered the moon of Saturn, 'Mimas.'
Saturn's moon, Enceladus, was discovered by William Herschel.
Astronomer Sir William Herschel discovered the first two moons of Uranus, Titania & Oberon.
Astronomer William Herschel first observed Uranus.
William Herschel discovered the first binary star.
Charles Messier discovered the Whirlpool Galaxy.
Johann Georg Palitzsch sighted the return of Halley's Comet.
German astronomer Gottfried Kirch discovered the Great Comet of 1680, the first comet sighted using a telescope.
Astronomers Jeremiah Horrocks and William Crabtree recorded the first known observation of a transit of Venus across the sun.
Cardinal Bellarmine condemned Galileo for stating that the earth revolved around the sun.
The Roman Inquisition ordered Galileo not to teach or defend his theory that Earth and other planets revolve around the sun.
Dutch astronomer Johannes Fabricius discovered sunspots.
Galileo Galilei discovered Callisto, the fourth moon of Jupiter.
Galileo discovered the first three satellites of Jupiter.
Astronomer Galileo demonstrated one of his earlier telescopes to Venetian lawmakers.
Kepler's Supernova was discovered.
Danish astronomer Tycho Brahe witnessed the supernova SN 1572.
A solar eclipse occurred, which started Tycho Brahe's interest in the world of astronomy.
Astronomer Nicolaus Copernicus made his first observation of Saturn.
A lunar eclipse saved explorer Christopher Columbus's life.
Astronomer Nicolaus Copernicus recorded his first observation after witnessing a moon eclipse with a distant star.
Saturn, Jupiter, and Mars came into alignment. Medieval scholars believed this phenomenon brought forth the Black Death.
The final gasps of the Crab Head nebula were observed as it went supernova.
Halley's Comet made its closest approach to Earth in recorded history.
A solar eclipse occurred, which is said to have marked the birth of the Greek legend Hercules.
