system
Given the following post, respond as if you're commenting on Reddit:
human
If they pointed the Hubble telescope back towards the Earth, what's the smallest thing it could see?

In other words, what kind of detail could it pick up?
gpt
The Hubble telescope has an angular resolution of 0.05 arcseconds and an orbital height of around 350 miles.  Pointed straight down at the surface of the earth, this translates to a spatial resolution of around 10 centimeters.  However, the telescope itself is optimized to look at things that are very far away, meaning they don't move very fast relative to Hubble's field of vision.  As a result, objects on the surface of earth are moving too fast for the telescope to "track" - so you can't actually get an image of the surface of earth using Hubble.