Throx

22nd is the Earthday celebration, there are actually two observances held in spring and autumn in both northern hemisphere and southern hemisphere respectively. The main reason of holding this event is to inspire the public for the awareness of Earth’s environment. Since January 1970, Earthday is celebrated every year around the world on 22nd April. Source: Wiki

If you are aware, Google search engine logo has been changed to Earthday logo to celebrate Earthday today.