At this time of year we tend to think of white Christmases and snowy scenes. Cards, cartoons and decorations often depict a cast of animals such as penguins, polar bears, seals, walruses and reindeer inhabiting these cold regions together. However the Arctic and Antarctic are not mirror images and the wildlife is very different. Polar bears, walruses and reindeer only live in the Arctic, penguins only live in the Antarctic, different species of seals can be found in both regions.

The Ancient Greeks derived names of the far north from the northern stars. Polaris or the North Star is the brightest star in the constellation of Ursa Minor. Another northern constellation, Ursa Major, was called the Great Bear and Artikos was the country of the Great Bear. The Ancient Greeks also realised that there would be an opposite to balance the world, and this was Antarktikos, the opposite of the Bear.

The North and South Pole, true north and true south, are fixed geographic points of 90 degrees at the location where the earth's axis of rotation meets the Earth's surface.

The Arctic/Antarctic are usually defined as the areas 90 to 60 degrees latitude. Above this latitude there is at least one day per year without a sunrise and another without a sunset, below it there is a sunrise and sunset every day.

At the poles the sun is permanently above the horizon in summer and permanently below the horizon in winter. This is because top of the Earth is tilted towards the Sun in northern summer and away from the Sun in northern winter.

Both the Arctic and Antarctic have a frigid climate and are treeless but are quite different in many ways.

The Arctic is an ocean surrounded by landmasses. The North Pole is a point in the middle of the Arctic Sea; the sea is covered by several metres of permanent sea ice. The Arctic encompasses a vast region of tundra (treeless plain) which is basically flat terrain.

The Antarctic is the coldest, driest, windiest continent on Earth. It contains the world's largest desert but also contains 90% of the Earth's ice and 75% of the Earth's fresh water. There are mountains over 5300 metres high and valleys over 2700 metres deep.

The Antarctic is much colder than the Arctic. The coldest temperature ever recorded was in Antarctica –89.6 degrees C. Average Arctic summer temperature is 0 degrees C; average Antarctic summer temperature is –32 degrees C.

Many species of mammals, birds and insects live in or migrate to the Arctic Ocean, coast and tundra including caribou, seals, musk ox, walrus, Arctic fox, wolves, lemmings and polar bears, but there are no penguins in the Arctic. Although the Arctic is treeless it supports vascular plants, lichens and mosses.

The Antarctic continent is hostile to all forms of life only a few microbes survive. Wildlife including penguins and seals live on the outlying coast and in the surrounding ocean.