Google marked Earth Day by releasing a new doodle where four seasons are replacing each other. 

The world celebrates International Mother Earth Day (Earth Day) on April 22, which was approved during 63rd Session of the UN General Assembly, and it is observed since 2010. 

Earth Day is an annual day on which events are held worldwide to increase awareness and appreciation of the Earth’s natural environment. It is coordinated by the Earth Day Network and is celebrated in more than 192 countries.