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. To capture the faint light reflected from the planet, a coronagraph must be used to block almost all of the star’s light. However, any instability in the telescope’s optics can lead to leakage of starlight and cause glare that masks the planet.

To overcome this challenge, precise control of both the telescope and instrument’s optical quality, or wavefront, must be achieved at 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. The use of adaptive optics systems can help correct any distortions in the wavefront and improve detection sensitivity.

Despite these challenges, recent advances in technology have made it possible to detect Earth-like planets using coronagraphy. In addition to coronagraphy, other techniques such as transit photometry and radial velocity measurements are also used to search for Earth-like planets. As our understanding of these planets grows, we may eventually be able to detect signs of life on them.

In conclusion, detecting an Earth-like planet presents a significant challenge due to its faintness compared to its parent star. However, with precise control over both telescope and instrumentation optical quality and advancements in technology, scientists are now able to search for these planets using various methods such as coronagraphy and other techniques like transit photometry and radial velocity measurements. With further research and development, we may one day be able to detect signs of life on these planets.