The Concept of Earth as a Home
At the time of the dinosaur extinction, Earth had served as a home that supported a particular set of physical environments that had changed only slowly for over a hundred million years. But then Earth changed quickly, and the dinosaurs died out. Today, Earth serves as a home to one species of human beings--over six billion individuals. We share our home with 5 to 10 million other species of plants and animals--many trillions of individuals--that live in today's physical environment. We not only share our home with these other life forms, but our lives depend on them. We are tied together in ways that we still do not fully understand.

Earth is still changing. Natural processes continue to change Earth slowly; there is a small possibility of natural catastrophes that will speed the tempo of environmental change. But there is a new process that has the potential to radically change the global environment within our own lifetimes: human modification of the environment. We human beings are "remodeling" our home at an ever increasing rate with unknown consequences. We all live here. There is no other "home" we can retreat to at this point. So the question is: Will we survive the changes we are making, or will we, like the dinosaurs, disappear from history?

Just as we know our individual environments well--where we turn on the lights or the water, where we keep clothing, where we go for shelter during a storm, how we obtain our food--we should know our planet well. Knowledge about our Earth home makes us efficient users of food, resources, and shelter. Knowledge about Earth helps us preserve our lives.

Understanding that we share our Earth home with other living things with which we are interdependent should give us a sense of stewardship for the planet. We can and must take care of our home so that our and our fellow creatures' descendants can also use and enjoy it.

The Earth Science Explorer is designed to lead students into discovery of our Earth home's processes, features, life forms, and history. Each problem students encounter has the potential of opening a doorway to further discovery of Earth's varied environments and the relationship between humans and those environments.