the Big Dipper; the Plough; the Plow
Refers to the prominent seven-star asterism within the constellation Ursa Major. In Japanese, 北斗七星 is more common; 北斗星 is a shorter variant used especially in astronomical contexts.
See also: 北斗七星
北斗星は北の空で見つけやすい。
The Big Dipper is easy to find in the northern sky.