Today, April 22, the 52nd World Earth Day is celebrated, designed to raise awareness of respect for the environment and the protection of the planet in general. Celebrated for the first time in 1970 – but on March 21, spring equinox -, it draws its origins from the concepts expressed by the American biologist Rachel Carsonnel, the book “Silent Spring” of 1962, an authentic green manifesto. However, seven years later, peace activist John McConnell, who spoke at a UNESCO conference in San Francisco, proposed its establishment: his idea was enthusiastically welcomed by the then secretary of the United Nations U Thant, the which led to the signing of a proclamation that formalized, with a list of precise principles and responsibilities, a commitment to take care of the planet. 36 leaders and personalities of world caliber would then join, including, in addition of course to U Thant himself, the anthropologist Margaret Mead, the astronaut Buzz Aldrin, the writer Isaac Asimov and the former Soviet president Mikhail Gorbachev. However, if today the anniversary falls on April 22 (a month and a day after the equinox) it is due to US Senator Gaylord Nelson, who with the help of the activist Denis Hayes proclaimed, also in 1970, an ecological teach-in which brought over 20 million Americans to the streets in defense of nature. It was then Hayes himself, in 1990, who transformed the Day into a global event for the first time. An extremely significant date in this sense, that of 22 April 2016, when the Paris agreement on climate change was signed on the occasion of Earth Day.