10 most difficult Arctic riddles

The word mammoth comes from the mythology of the Siberian peoples who believed they lived underground - as dead ones were found in the ground from time to time.

Auroras are produced when the magnetosphere is sufficiently disturbed by the solar wind that the trajectories of charged particles in both solar wind and magnetospheric plasma, mainly in the form of electrons and protons, precipitate them into the upper atmosphere (thermosphere/exosphere) due to Earth's magnetic field, where their energy is lost.

In a three year journey between 1903 and 1906, Amundsen explored the passage with a crew of no more than six, in the converted 47-ton herring boat Gjøa. Spending winters with ship trapped in ice, he learned from the local Netsilik people about Arctic survival skills that would later prove useful. For example, he learned to use sled dogs and to wear animal skins in lieu of heavy, woolen parkas. Amundsen later led the expeditions to discover the South Pole (1911) and the North Pole (1926).

When a piece of iceberg ice melts, it makes a fizzing sound called "Bergie Seltzer". This sound is made when the water-ice interface reaches compressed air bubbles trapped in the ice. As this happens, each bubble bursts, making a 'popping' sound. The bubbles contain air trapped in snow layers very early in the history of the ice, that eventually got buried to a given depth (up to several kilometers) and pressurized as it transformed into firn then to glacial ice.

Alaska was colonized by Russian fur traders. Rather than hunting by themselves, the Russians forced the Aleuts to do the work for them. Many of Aleuts had been removed from their home islands and sent as far south as California to hunt sea otter.

An ice sheet is a mass of glacier ice that covers surrounding terrain and is greater than 50,000 km2 this is also known as continental glacier. The only current ice sheets are in Antarctica and Greenland; during the last glacial period at Last Glacial Maximum the Laurentide ice sheet covered much of North America, the Weichselian ice sheet covered northern Europe and the Patagonian Ice Sheet covered southern South America.

The average discharge of the Yenisei is 19,600 m³/s. It is more than the Mississippi, Ganges or Paraná.

The permafrost prevents trees from developing a deep root system. Climate variations or forest fires can thaw the upper extents of the permafrost, creating a ground slump called thermokarst.

The first nautical transit of the North Pole was made in 1958 by the submarine USS Nautilus, and the first surface nautical transit occurred in 1977 by the icebreaker NS Arktika.

The total length of the river is 1982 miles (3190 km). There are only four vehicles-carrying bridges across the Yukon River.