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For nine years, this Milky Way mapper has pinpointed over a billion stars to create an expansive dataset

This sky map from Gaia is based on measurements of nearly 1.7 billion stars, showing off the galactic plane, interstellar dust and neighbouring galaxies his almost sombrero-shaped spacecraft has been mapping the stars of our galaxy for nine T years. Its first data release contained unrivalled information on nearly 1.7 billion stars, and is to date the greatest catalogue of stars ever produced. The European Space Agency (ESA) initially had the idea of using Gaia as an optical interferometer mission – meaning that Gaia originally would have been a series of smaller telescopes working together to create an image similar to that of a larger telescope – thus the ESA gave the mission its original name: the Global Astrometric Interferometer for Astrophysics, or GAIA. After the mission evolved and the interferometer idea was dropped, the name stuck. However, the previous design was altered and Gaia’s primary objective would be to create the largest, most precise three-dimensional map of the stars in our galaxy within its intended five-year mission, building on the legacy of the Hipparcos mission.

The name wasn’t the only aspect that changed. Launch was originally scheduled for December 2011. After a series of complications to Gaia and the liftoff schedule, the spacecraft finally left Earth two years behind schedule, riding aboard a Soyuz-Fregat rocket. With a launch mass of 2,030 kilograms, Gaia was sent on its way to its new home at Lagrange point 2 (L2) roughly 1.5 million kilometres (932,057 miles) away from Earth. This is an ideal location to observe the wider universe, and is a cosmic ‘parking spot’ which relies on the gravity of the Sun and Earth to keep the space observatory fixed in this one spot. While at L2, Gaia is in a Lissajous-type orbit that has a period of about 180 days around a fixed point at L2.