Indigenous people of the Arctic regions often use reindeer skin to make clothing.
New Denmark is the name in Lyra's world for the USA - Lee Scoresby is from Texas.
The panserbørne (literally "armour-bears" in Danish) are based on polar bears, which are native to the Svalbard in our world and have become the islands' symbol and primary tourist attraction.
The polar bear is the world's largest land carnivore, with adult males growing up to 680 kg. Their fur is in fact clear and their skin black, but due to the thickness of the fur it appears white, allowing them to blend with their habitat. The fur sometimes yellows over time, suggesting Iorek is not a young bear.
Polar bears are far less territorial than other bears, and tend to be more cautious when confronted. However if they are hungry they can be unpredictable and have been known to kill and eat humans.
They are classified as "vulnerable" in conservation terms, because of the rapid depletion of their habitat due to the melting of the Polar ice caps.
There is little scientific evidence for the Aurora producing an audible noise – the atmosphere is so thin that sound waves would not be carry, and the Aurora itself is so far away that it would take sound waves 5 minutes to reach us.
However, there are several reports of people hearing, as Lyra does, a "swooshing" sound when viewing the aurora. There is a very interesting paper here which investigates the subject more thoroughly.
Vertigo is the feeling of movement when one is actually stationary. It causes dizziness and potentially nausea.
Kaisa is a snow goose, common in Siberia, Greenland and Alaska. He is the slightly rarer "blue" snow goose, whose plumage is a smokey bluish-grey, except for the white head and tail tip.
vangar means "grass plains" in Norwegian
Hazard is an old English game of chance played with dice.
It seems this is not the game Lee is proposing, as he proceeds to shuffle and deal a deck of cards.
Learn to play the dice version here.