Captain PlanetSept. 15, 1920: Zion National Park, featuring the canyons and red rock wilderness of Southern Utah, is dedicated.

Sept. 15, 1971: John C. Cormack lends his boat, a halibut seiner, to a scruffy band of activists. They sail from Vancouver, Canada, toward the Amchitka, more than 1,000 miles away in the Aleutian Islands, in a bid to disrupt a planned underground nuclear weapons test by the U.S. government. The voyage fails to stop the detonation, but Greenpeace is born, and the U.S. shuts down the test site soon after.

Sept. 15, 1990: "Captain Planet" (at right), a cartoon series about an earth-saving superhero, debuts on Turner Broadcasting.

Sept. 15, 2012:  The World Meteorological Organization announced that the ozone hole over Antarctica will be smaller in 2012 than in the previous year.  WMO said this is evidence that the United Nations ban on ozone-depleting chemicals was having an impact.

Photo: andertoons/Flickr

This feature is compiled by Peter Dykstra, an MNN contributor and publisher of Environmental Health News and The Daily Climate.