Today is Earth Day! It's celebrated every year by more than a billion people in 180 nations around the world.

It was created back in the 60s to increase public awareness of environmental problems and is now celebrated around the world.

This year, NASA is getting involved by building a large image of the earth from the ground up. That image will include portraits of people in those places today.

Wanna take part? Print out the Global Selfie page (link below) and write down where you are. Then post your selfie on social media (Twitter, Facebook, Flickr, Instagram, etc.) with the hashtag #globalselfie.

NASA will put all of the pictures together for one large mosaic of earth and its people. That picture will be released in May.