Earth Day ecology flag

According to Flags of the World, the Ecology Flag was created by cartoonist Ron Cobb, published on November 7, 1969, in the Los Angeles Free Press, then placed in the public domain. The symbol is a combination of the letters "E" and "O" taken from the words "Environment" and "Organism," respectively. The flag is patterned after the United States' flag, with thirteen alternating-green-and-whites stripes. Its canton is green with a yellow theta. Later flags used either a theta or the peace symbol. Theta would later become associated with Earth Day, which is appropriate due to the fact that theta is the eighth letter of the Greek alphabet and there are eight letters in "Earth Day".


Ron Cobb created an ecology symbol which he published on November 7, 1969, in the Los Angeles Free Press and then placed it in the public domain. The symbol was formed by taking the letters "e" and "o", taken from the words "environment" and "organism", and putting them in superposition, thereby forming a shape reminiscent of the Greek letter Θ (Theta). Look magazine incorporated the symbol into an image of a flag in their April 21, 1970 issue. 

The flag was patterned after the flag of the United States, and had thirteen stripes alternating green and white. Its canton was green with the ecology symbol where the stars would be in the United States flag.