
This gift comes from the European Space Agency’s (ESA’s) $1-billion Gaia telescope, launched in 2013 on a decade-long mission to measure the motions, positions and other key properties of billions of stars in and around our galaxy.

Already this new trove is being put to use, with eager astronomers poring through its data, hoping to unlock some of our galaxy’s most intriguing secrets in a way never before possible. Inside is a most welcome gift-a vast catalogue of more than a billion stars in and around our galaxy, the most advanced of its kind ever made. Three weeks before Christmas, astronomers are opening one of their presents early.
