2.5 hours captured on image. The Earth's extended axis ends up one degree from the North Star in the sky so with a longer exposure directed towards the North Star it looks as if the stars are spinning around it. The Vikings knew about this star and could navigate by it. During the exposure, some auroras were also formed low in the north.
Airglow is a faint emission of light by a planetary
atmosphere. In the case of Earth's atmosphere, this optical phenomenon causes
the night sky never to be completely dark, even after the effects of starlight
and diffused sunlight from the far side are removed. This phenomenon originates
with self-illuminated gases and has no relationship with Earth's magnetism or
sunspot activity, causing aurorae.
The Big Dipper is an asterism consisting of seven bright
stars of the constellation Ursa Major six of them are of second magnitude and
one, Megrez, of third magnitude. Four define a "bowl" or
"body" and three define a "handle" or "head". It
is recognized as a distinct grouping in many cultures. The North Star
(Polaris), the current northern pole star and the tip of the handle of the
Little Dipper (Little Bear), can be located by extending an imaginary line
through the front two stars of the asterism, Merak and Dubhe. This makes it
useful in celestial navigation.
