Detecting an Earth-like planet is a significant challenge due to the fact that it is approximately 10 billion times fainter than its parent star. The key obstacle lies in the need to block almost all of the star’s light in order to capture the faint light reflected from the planet. This requires the use of a coronagraph to block the starlight, but any instability in the telescope’s optics, such as misalignment between mirrors or a change in the mirror’s shape, can lead to leakage of starlight and cause glare that masks the planet.
To overcome these challenges, detecting an Earth-like planet using a coronagraph necessitates precise control of both the telescope and the instrument’s optical quality, or wavefront, to an exceptional level of 10s of picometers (pm). This is roughly on the order of the size of a hydrogen atom, emphasizing the extraordinary precision needed for this endeavor. In addition, new techniques such as adaptive optics are being developed to improve detection efficiency and reduce noise levels. With continued advancements in technology and techniques, it may become possible to detect more Earth-like planets around nearby stars in our galaxy.
