High def earth
Blue Marble: An image of the Earth taken from NASA Earth-observing satellite Suomi NPPNASA/NOAA/GSFC/Suomi NPP/VIIRS/Norman Kuring

Nasa has invited the planet to take part in a celebration of this year's Earth Day with the agency's Global Selfie campaign.

Held annually worldwide to support environmental protection, Earth Day was first celebrated in 1970 and is now coordinated globally by the Earth Day Network. Gaylord Nelson, a United States senator, founded Earth Day as an environmental teach-in held on 22 April each year. An organisation led by Denis Hayes, an environmental activist and proponent of solar power, turned the day into an international celebration in 1990 by organising events in 141 countries.

For Nasa, 2014 marks a year of discovery for our planet and the surrounding solar system. The agency has launched five missions designed to gather critical data about Earth as a part of the Earth Right Now campaign, to understand more about global warming and the build-up of greenhouse gases.

What is a #GlobalSelfie?

While Nasa satellites capture new images of Earth from space every second, the agency are trying to create an image of the planet from the ground using portraits of the people on Earth. Once the pictures stream around the world on Earth Day on social media, with the hashtag #GlobalSelfie, they will be used to create a mosaic.

Nasa have asked that people "get outside and show us mountains, parks, the sky, rivers, lakes" with a sign telling everyone where you are - which are available to print on the Nasa website. You can also write your location in the sand or spell it out with rocks, and the Earth mosaic image will be released in May.

How do I take part?

Nasa will monitor photos posted on Twitter, Instagram, Facebook, Google+ and Flickr. Post your photo to Twitter, Instagram or Google+ using the hashtag #GlobalSelfie, or post it to the #GlobalSelfie event page on Facebook, the #GlobalSelfie group on Flickr or join the #GlobalSelfie Google+ event page.

Why a #GlobalSelfie?

The agency has helped identify thousands of new planets in the universe over recent years, but studies no planet more closely than our own. There are 17 Earth-observing missions orbiting the planet at the moment, with several more to come in the near future.

While satellite data helps Nasa scientists piece together scientific information on Earth, the #GlobalSelfie campaign will create a different picture of the planet. The crowd-sourced collection of images will be used to create a giant, unique insight into life on the Blue Marble.