Very Small KBO

Explanation: In 2010 NASA's Hubble Space Telescope discovered the smallest object ever seen in visible light in the Kuiper Belt, a vast ring of icy debris that is encircling the outer rim of the solar system just beyond Neptune. This artist's concept of the needle-in-a-haystack object found by Hubble is only 3,200 feet across and a whopping 4.2 billion miles away. The smallest Kuiper Belt Object (KBO) seen previously in reflected light is roughly 30 miles across, or 50 times larger.

Pluto

Image credit: NASA, ESA, and G. Bacon.