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.

  • 3
    $\begingroup$ About 10 cm in diameter at Low Earth Orbit. Capability for anything less is classified. $\endgroup$ Dec 19, 2014 at 12:38
  • $\begingroup$ wow! 10cm object from LEO? Amazing $\endgroup$
    – Sathish
    Dec 19, 2014 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, 2014 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. $\endgroup$ Dec 19, 2014 at 19:01
  • $\begingroup$ As Wayfaring Stranger says, the telescope with the lowest angular resolution can lead to the answer $\endgroup$
    – Sathish
    Jan 2, 2015 at 6:20

1 Answer 1


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.


You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .