The Gaia space observatory has detected unusual stellar earthquakes that arise from dramatic events in the outer layers of stars, phenomena that resemble earthquakes on Earth. Conny Aerts, a professor at the Institute of Astronomy at the Catholic University of Leuven in Belgium, notes that these stellar pulsations reveal much about how stars work on the inside. He is part of a large network of Gaia collaborators, and his description emphasizes large-scale surface disturbances that temporarily alter a star’s shape. Initially, Gaia was not designed to study such pulsations, yet it has identified powerful surface shifts across thousands of stars, including cases where stellar earthquakes have rarely been observed before. In several instances, the detected oscillations are not purely radial, meaning they do not simply grow and contract in a uniform, spherical manner around a central point.
These odd starquakes are among Gaia’s many discoveries since the mission began. Launched in 2013, Gaia was built to produce the most accurate and comprehensive three-dimensional map of the Milky Way. Its operations are based at the L2 Lagrange point, about 1.5 million kilometers from Earth. The European Space Agency has issued multiple data releases from Gaia, with the third set offering descriptions of nearly 2 billion stars across the galaxy. The data provide new insights into the chemical makeup of stars, their surface temperatures, masses, and ages, as well as the speeds at which stars move toward or away from the Sun. The mission also yields detailed information about the properties of cosmic dust that fills the interplanetary space among more than 150 thousand asteroids and stars in the solar system. A special issue of Astronomy and Astrophysics discusses Gaia findings, and roughly 50 scientific papers have been published based on Gaia data to date. These studies collectively advance understanding of how stars evolve and interact with their environments, illustrating Gaia’s broad scientific impact across multiple domains of astronomy. (Gaia Collaboration, Europe, 2023–2024 attribution)