1604    Kepler's Star: German astronomer Johannes Kepler observes a supernova in the constellation Ophiuchus.

1612    Galileo Galilei becomes the first astronomer to observe the planet Neptune, although he mistakenly catalogued it as a fixed star.

1804    Juno, one of the largest main belt asteroids, is discovered by German astronomer Karl Ludwig Harding.

1846    Neptune is discovered by French astronomer Urbain Jean Joseph Le Verrier and British astronomer John Couch Adams; the discovery is verified by German astronomer Johann Gottfried Galle.

1925    The American astronomer Edwin Hubble announces the discovery of galaxies outside the Milky Way.

1976    The Jovian-Plutonian gravitational effect hoax is first reported by British astronomer Patrick Moore.

1994    The first discoveries of extrasolar planets are announced by astronomer Alexander Wolszczan.

2005    Astronomers announce their discovery of the dwarf planet Eris.