For 50 years - since April 22, 1970 - Earth Day has been celebrated as a day of action and education in pursuit of improving the environment. Starting as a response to industrial pollution in the United States, Earth Day activities now occur in over 400 countries and involve a billion people (per earthday.org). While initially targeting industrial waste, air pollution, and litter as its main action items, Earth Day has pivoted to include global recycling campaigns and efforts to tackle the looming challenge of climate change, among other initiatives.

Earth Day's fundamental goals haven't changed: bringing environmental issues into open discourse, teaching people about both the causes and remedies that can be used, and inspiring people wherever its message reaches to actively participate in making the earth a safer, healthier place for all of its inhabitants - human, animal, and plant alike.