Pluto was discovered by Clyde Tombaugh on 18 February 1930.
He used a technique similar to what the animated GIF shows, by looking at the same field taken on different nights and seeing what moved. (Hint, look in the lower left)
Bobinas P4G is a social network. It runs on GNU social, version 2.0.1-beta0, available under the GNU Affero General Public License.
All Bobinas P4G content and data are available under the Creative Commons Attribution 3.0 license.