The other day, Niantic announced that a Pokemon Go event centered around the Equinox would be going live in just a little while. The official twitter has announced that it is live now, encouraging players to have fun exploring their neighborhoods.
During the event, PokeStops and Gyms you visit will net you special 2 km Eggs that can hatch Chansey, Mareep, Larvitar, and others. You can also get special boxes from the in-game shop that feature items like Lucky Eggs, Lure Modules, and the new Super Incubators for hatching eggs quicker.
Any Pokemon you add to your Pokedex during this event earns you triple the normal XP, encouraging players who have yet to take on the Legendary Pokemon to take the task on now. The event ends on October 2 at 1:00 PDT, so make sure to take advantage while you can.