Answer: earthday

AnswerCrossword Clue
EARTHDAY

4-22 green event

EARTHDAY

Environmentalists' celebration

EARTHDAYEnvironmentalist's celebration
EARTHDAY

Its flag depicts the Blue Marble

EARTHDAY
April, 1970, event
EARTHDAY
April, 1970, happening
EARTHDAYApril celebration
EARTHDAYObservance first celebrated in 1970
EARTHDAYApril 22