The launch of the Gaia star-mapping mission in December 2013 became the pinnacle of a scientific pursuit spanning thousands of years. At the dawn of the recorded history, the earliest human civilizations had already watched the positions of stars to track the calendar, to navigate on land and at sea, to foretell the future and, perhaps, to understand the Universe. Astronomers in ancient Greece are credited with designing some of the earliest tools for measuring and predicting the positions of celestial bodies.
Over the next two thousand years, astronomers around the world perfected their instruments and compiled ever more voluminous catalogs of stars. As astronomy became more diversified, its oldest subfield of tracking and cataloging the stars became known as astrometry.