We already know that the stars of the Milky Way orbit its center, and Gaia has measured their speeds and movements with unprecedented accuracy. The telescope also discovered that the Galactic disk wobbles over time, much like a spinning top. Overall, Gaia — which ceased operations last March — has given us the largest and most precise multidimensional map of our galaxy.

Now, a new analysis of Gaia’s data provides fresh insight: a massive wave is shifting stars tens of thousands of light-years from the Sun. According to ESA’s announcement, this galactic wave resembles the ripples spreading outward when a stone is thrown into a lake.

The maps created with Gaia’s data show the wave stretching across a vast region of the Galactic disk, influencing stars located between 30,000 and 65,000 light-years from the Galactic center.

Researchers identified this motion by studying the precise positions and movements of young giant stars and Cepheids — a type of variable star used as key markers for measuring galactic and extragalactic distances. As these stars move with the wave, scientists believe that gas in the Galactic disk may also be caught in this ripple-like flow.

The origins of these galactic oscillations remain unknown. One possible explanation could be an ancient collision with a dwarf galaxy, though this requires further investigation. The massive wave might also be linked to a smaller-scale ripple observed about 500 light-years from the Sun, in a different part of the Galactic disk, known as the Radcliffe Wave.

The findings were published in the journal Astronomy and Astrophysics.