Each of the following sites captures the imagination with its natural power and beauty. And they have one thing in common: Nothing made by humans can approach their majestic dignity.

1. Grand Canyon

The Grand Canyon in northwestern Arizona was formed by the erosive power of the weather and the Colorado River and its tributaries as they scoured away billion-year-old rocks. Although known to Native Americans for thousands of years, the vast gorge was not discovered by the first Spanish explorers until 1540. Grand Canyon National Park was established in 1919, preserving the more than 1.2 million acres of colorful cliffs and waterways that are home to 75 species of mammals, 50 species of reptiles and amphibians, 25 species of fish, and more than 300 species of birds.

The canyon stretches 277 miles, with some sections reaching a mile deep and 18 miles across. More than five million visitors view the canyon annually, often hiking or riding mules down to the canyon floor, while the more adventurous opt for boating or rafting the Colorado River through the canyon.

2. Aurora Borealis (Northern Lights)

The aurora borealis (also called the northern lights) consists of awe-inspiring twirls of light in the sky, caused by "solar wind" -- electrically charged particles interacting with Earth's magnetic field. The aurora borealis can be up to 2,000 miles wide, but it fluctuates in size, shape, and color, with green being the most common color close to the horizon while purples and reds appear higher. Named after Aurora, Roman goddess of dawn, and Boreas, Greek god of the north wind, these ribbons of color are best viewed in northern climates like Alaska but have been seen as far south as Arizona.

The aurora borealis is also called the northern lights and is best viewed in northern climates.

3. Mount Everest

Mount Everest, part of the Himalayan Mountains between Nepal and Tibet, was formed about 60 million years ago due to the shifting of Earth's rocky plates. Named after Sir George Everest, a British surveyor-general of India, Everest is the highest mountain on Earth, looming some 29,035 feet high and growing a few millimeters every year.

Climbing Everest isn't easy, due to avalanches, strong winds, and thin air. Nevertheless, in 1953, Edmund Hillary and Sherpa Tenzing Norgay were the first climbers to reach the peak. More than 700 others have done so since, with at least 150 persons dying on their quest.

Victoria Falls and the Great Barrier Reef are included on the second part of our list of the 7 wonders of the natural world. Learn about them on the next page.