Gaia detects exoplanets using a technique called microlensing. When a massive object, such as a planet, passes between Earth and a distant star, it causes a slight distortion in the light from the star. This distortion can be detected by Gaia, allowing astronomers to infer the presence of an exoplanet.
However, Gaia is not specifically designed for exoplanet detection, and its microlensing capabilities are limited. It is more suitable for studying bright stars located in the central region of our galaxy, where the chances of detecting microlensing events are higher. Therefore, while Gaia has discovered a handful of exoplanets, its primary focus remains on studying the stars and structure of the Milky Way.
On the other hand, there are other space missions and ground-based observatories dedicated to exoplanet detection. These missions use different techniques, such as the transit method and radial velocity method, to identify and characterize exoplanets. For instance, NASA's Kepler mission, which operated between 2009 and 2018, discovered thousands of exoplanets using the transit method.
To find planets that are Earth-like in terms of size, composition, and distance from their stars, astronomers employ sophisticated techniques and observations from multiple facilities. The ultimate goal of finding Earth analogs and potentially habitable exoplanets requires specialized instruments and missions designed specifically for this purpose.
