“The cosmic game changed forever in 1992. Before then, logic told us that there had to be other planets besides the nine (if you still count poor Pluto) in our solar system, but until that year, when two astronomers detected faint, telltale radio signals in the constellation Virgo, we had no hard evidence of their existence.” -Thomas Mallon
For generations, if you wanted to know what the surface of the outermost known object in our Solar System — Pluto — looked like, you had to rely solely on your imagination. Sure, it was probably covered in ice, and large enough to pull itself into a sphere, but beyond that, little was known. Even with the Hubble Space Telescope, little detail could be made out; the best resolution was still hundreds of kilometers per pixel.
That all changed in 2015, when the New Horizons spacecraft flew by Pluto for the first time. Reaching a minimum distance of just 12,500 km from this world, we were able to image large parts of its surface and atmosphere at resolutions of 80 meters (260 feet) per pixel. What we discovered was a diverse, rich world as geologically interesting as any planet we’ve ever found.