With the help of their precise positions measured by Gaia, a new high-precision reference system can be constructed for defining the positions of stars, Solar System objects, and also satellites. The precise observations of quasars resulted, for the first time, in a successful computation of the acceleration of the Solar System. Solar System researchers at the University of Helsinki take part in the Gaia data processing in several different ways. Argelander was the first astronomer, who unequivocally calculated the direction of Solar System motion in space. Gaia has, in essence, measured the absolute motion of the Solar System relative to the distant universe.
