From the March 2006 issue

How can the Hubble Space Telescope (HST) take pictures of objects light-years away but not get a good picture of Pluto?

By | Published: March 1, 2006 | Last updated on May 18, 2023
Hubble after Servicing Mission 3b
Pluto is very small. At its distance, it subtends a smaller angle on the sky than does a galaxy at a distance of billions of light-years. Consequently, even HST cannot resolve the planet’s surface very well, because that would require a resolution of better than about 0.1″. Still, HST has produced a spectacular image of Pluto and its moon Charon. — DANIEL CHRISTLEIN, UNIVERSIDAD DE CHILE AND YALE UNIVERSITY