Earth is the third planet from the Sun. More than two-thirds of this beautiful planet is covered with water. At the North and South Poles, this water is in the form of ice. Ice is also plentiful in many other cold areas of the planet.

Many scientists think the water may have originally come from comets crashing into the newly formed Earth. We may have comets to thank for the conditions that made life possible on Earth!

Tiny microscopic organisms have been found living in extremely cold, icy environments on Earth. That leads scientists to think that this kind of life may be found in other icy environments elsewhere in the solar system.

This image was taken by the Apollo 17 astronauts on their way home in 1972.

The Lambert Glacier in Antarctica. This is Earth’s largest glacier. In the center is an icefall. Ice flows like liquid water, but much more slowly.

This image is from LandSat 7.

The fjords of northern Norway. Dark, cold fingers of ocean water reach into the snow-covered mountainous coastline.

This image is from the ASTER instrument on the Terra satellite.

Akpatok Island in northern Quebec, Canada. The island is covered with snow and surrounded by ice floes.

This image is from LandSat 7.

This is the Kamchatka Peninsula of Russia. The mountains are white with snow and glaciers glide slowly through the valleys, depositing their blue ice in the shallow coastal waters.

This image is from the ASTER instrument on the Terra satellite.