Searching for“another Earth”

The detection of exoplanets, especially the habitable planets, is a hot issue. Searching for “another Earth” is a milestone to answer some crucial scientific issues, e.g. “How was life initiated?”, “Are we alone in the universe?”. In this article, we briefly introduce both the general theories of planet formation and evolution, and different detection methods. Neither the radial velocity or transit method, currently the most popular methods for finding exoplanets, can detect another Earth in another solar system. To characterize exoplanets in the near future, direct imaging is necessary, instead of indirect detection through seeing the changes in their star’s motion. Interferometry via synthetic apertures can achieve both high contrast and high angular resolution, thus it is thought to be the most probable way to image another Earth. China has proposed the “Miyin” project, which aims to be the first to image exoplanets via interferometry, and will try to make a significant breakthrough in finding another Earth.