Detecting an Earth-like planet is a significant challenge due to the fact that the planet 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. However, 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.

As a result, 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.

To achieve this level of precision, scientists must use advanced techniques such as adaptive optics and active wavefront control. These techniques allow them to correct for any distortions or aberrations in the telescope’s optics and ensure that all starlight is blocked and only faint light from planets is captured.

The success of these techniques has led to significant advancements in exoplanet detection, allowing scientists to discover thousands of potentially habitable worlds beyond our own solar system. However, detecting an Earth-like planet remains one of the most challenging tasks for exoplanet detection teams due to its inherent faintness and distance from its parent star.

Overall, detecting an Earth-like planet requires a combination of advanced technology and exceptional precision. While it may be difficult at times, these challenges are worth it as they bring us one step closer to discovering extraterrestrial life beyond our own world.