January 5: Galileo Galilei points his newly developed telescope at the sky and observes craters and mountains on the Moon, moving spots on the Sun, four moons revolving around Jupiter, the phases of Venus, and the almost innumerable stars of the Milky Way. Jan 4 thru 15, 1601 are called by some the most important days in the history of astronomy.

January 6: Galileo Galilei points his newly developed telescope at the sky and observes craters and mountains on the Moon, moving spots on the Sun, four moons revolving around Jupiter, the phases of Venus, and the almost innumerable stars of the Milky Way. Jan 4 thru 15, 1601 are called by some the most important days in the history of astronomy.