The first Earth Day, April 22, 1970, hailed as the birthday of modern environmentalism, is going to have a sequel in 1990 that organizers hope will dwarf the original.
Today a diverse group of environmentalists and political figures announced plans for ''Earth Day 20,'' the start of a two-year program of educational projects, demonstrations and community events all over the world.
The group included an environmental scientist, Barry Commoner; the Rev. Jesse Jackson; a former Cabinet Secretary, Elliot L. Richardson, and a grass-roots environmentalist, Lois M. Gibbs. This is one of at least half a dozen groups that are planning Earth Day celebrations next year. One is being organized by Denis Hayes, who coordinated the original Earth Day.
While the first Earth Day was observed only in the United States, next year's will be international.
One symbolic event will be an effort to scale Mount Everest and reach the summit on April 22, 1990, by a three-member team of climbers from the United States, the Soviet Union and China. If the team reaches the summit, it plans to make a live television broadcastappealing for peace and protection of the environment.