Why is the third IAU criterion (clearing the neighborhood) generally untestable for most exoplanets?

Answer

Current observational technology cannot map the debris fields around distant star systems with the necessary precision

Determining whether an exoplanet has cleared its neighborhood requires a level of precision in mapping debris fields light-years away that current observational technology cannot achieve.

Why is the third IAU criterion (clearing the neighborhood) generally untestable for most exoplanets?

#Videos

What is a Planet? - Science at NASA - YouTube

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