Two parts of the earth are bitter cold all year round. These places are the "top" and the "bottom" of the earth - the North Pole and South Pole.
The land around the South Pole is called Antarctica. It is the coldest place on earth. Antarctica is covered with a sheet of ice more than a mile (1.6 kilometers) thick. But beneath the ice there is land, just like other land, with mountains, plains, and valleys.
At the North Pole there is no land. This part of the world is just a huge sheet of ice from four to ten feet (1.2 to 3 meters) thick. Beneath the ice there is only the water of the Arctic Ocean.
Scientists know that ten or twenty million years ago there was no ice at the North and South poles ! Palm trees grew in Antarctica, and animals such as those that now live only in hot places lived there ! But something happened to turn the two poles into regions of ice.
We don't know why the poles became covered with ice, but we know why the ice does not melt. It is because the sun never shines directly down on the poles. Because the sun is usually low in the sky, the air stays cool. Thus, the poles get much less heat than the rest of the earth. And most of the heat they do get bounces off the shiny, white ice and is reflected back out into space. So the poles never get enough heat to melt all the snow and ice.
The land around the South Pole is called Antarctica. It is the coldest place on earth. Antarctica is covered with a sheet of ice more than a mile (1.6 kilometers) thick. But beneath the ice there is land, just like other land, with mountains, plains, and valleys.
At the North Pole there is no land. This part of the world is just a huge sheet of ice from four to ten feet (1.2 to 3 meters) thick. Beneath the ice there is only the water of the Arctic Ocean.
Scientists know that ten or twenty million years ago there was no ice at the North and South poles ! Palm trees grew in Antarctica, and animals such as those that now live only in hot places lived there ! But something happened to turn the two poles into regions of ice.
We don't know why the poles became covered with ice, but we know why the ice does not melt. It is because the sun never shines directly down on the poles. Because the sun is usually low in the sky, the air stays cool. Thus, the poles get much less heat than the rest of the earth. And most of the heat they do get bounces off the shiny, white ice and is reflected back out into space. So the poles never get enough heat to melt all the snow and ice.
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