Gaia's Quest: Searching for Another Earth
The European Space Agency's Gaia mission, which aims to map over one billion stars in the Milky Way, has the potential to detect Earth-like planets up to 30 light-years away using astrometry. Gaia's astrometry method allows for more accurate determination of an exoplanet's orbital parameters and can detect planets far away from their host stars. If advanced astrometry precision is achieved, Gaia could detect the four giant planets in our solar system within 100 years. Additionally, over 300 stars within ten parsecs from our solar system could potentially detect Earth if they achieve microarcsecond accuracy. The possibility of extraterrestrial intelligences (ETIs) using similar technology to Gaia raises the question of whether they could discover planets in our solar system, including Earth.