Earth -- The Ever-Changing Planet

Earth -- our home in the universe -- is a complex, dynamic, and ever-changing planet.

Walk outside and watch the clouds moving overhead, or a thunderstorm building up and then unleashing a downpour. Perhaps you have lived through a hurricane sweeping onto land from the sea and wreaking havoc on a community.

Change is unavoidable!

Humans, too, do their share in bringing about change. If you could have been an astronaut 100 years ago and looked down on Earth from orbit, you would have seen a world very different from today's. There would have been few city lights 100 years ago. The rain forests would have been more extensive.