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What is the minimum size of an object that can be observed from Earth with our most powerful telescope?

I understand that the answer depends on how far the object is from Earth. For the sake of discussions let us consider distances less the orbit of Neptune.

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    $\begingroup$ About 10 cm in diameter at Low Earth Orbit. Capability for anything less is classified. $\endgroup$ – Deer Hunter Dec 19 '14 at 12:38
  • $\begingroup$ wow! 10cm object from LEO? Amazing $\endgroup$ – Sathish Dec 19 '14 at 13:02
  • $\begingroup$ Do meteorite dust specks count? If the distance is less than Neptune, would it include objects actually on Earth? $\endgroup$ – user21 Dec 19 '14 at 17:10
  • $\begingroup$ Sathish is asking how small an object, at the distance of Neptune, can be resolved by a telescope on the earth's surface. Does anyone know what scope holds the current record for angular resolution? That and simple geometry would answer this question. $\endgroup$ – Wayfaring Stranger Dec 19 '14 at 19:01
  • $\begingroup$ As Wayfaring Stranger says, the telescope with the lowest angular resolution can lead to the answer $\endgroup$ – Sathish Jan 2 '15 at 6:20
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The smallest natural object that I know of that has been detected from an Earth-bound telescope is 2011 CQ1, a one-meter asteroid observed while specifically looking for NEOs.

As DeerHunter mentions in a comment, smaller artificial objects are identified and tracked, mostly by NORAD and some other national defence centers.

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