While other dates have been called Earth Day it is obvious that a singular Earth Day is needed and that the original choice of nature's day is best. More attention for this fact will increase the influence of Earth Day and its benefits.
Every effort to encourage Earth care is to be commended. But just as more than one birthday each year for an individual would diminish the real birthday, calling other dates Earth Day detracts from the authentic day -- which can provide a more meaningful focus and obtain more unity in our diversity. The nature of the March equinox provides a reason for an event at the same time all over the world.