The North Sea is the brightest star in the Big Dipper. For observers in the Northern Hemisphere, it occupies a special place. Only half a degree off the Earth’s axis, so when the Earth spins day and night, the North Pole stands almost still on the North Pole.
In modern astronomy, this star is an array of seven stars, the seven brightest within the boundaries of the constellation Daxin in the northern hemisphere. There are many other stars in the Big Dipper star.
Westerners also have their own names for these stars. After being codified on an astronomical map, the stars all have an astronomical science name in the constellation Ursa Major.
“Bắc Đẩu” is a folk calling for a group of stars composed of many stars.
Position 7 The North Star cluster brightens in the sky.
Because the Earth is spherical, the location of the North Pole on the horizon depends on the position of the observer. Specifically, the angle between the northern horizon and the North Pole is equal to the latitude of the observer. For example, viewed from the equator (latitude 0), the North Sea lies at the northern horizon. When moving to Houston, Texas (latitude 30), the North Sea lies 30 degrees above the horizon. When moving to the North Pole, the North Sea lies 90 degrees above the horizon, which is right above the observer’s head.
In the past, northern sailors measured the angle between the horizon and the North Sea to determine their latitude. However, latitude alone is not enough to determine a location on the surface of the Earth. So while many cultures successfully make expeditions at sea based on observing stars, the weather, and currents, the “longitude problem” has been the horror of sailors for millennia. century.
There are no stars in the Southern Hemisphere corresponding to the North. Moreover, the North Pole is not a very accurate indication of the North Pole, because in addition to the 24-hour rotation cycle, the Earth’s axis also moves in a cone. Therefore the projection of the earth’s axis in the sky will be a cycle of 26,000 years. So the North Sea also changes over time. 5,000 years ago, the Earth’s axis headed for the constellation Draco and the Big Dipper was the star Thuban. Similarly, 12,000 years later, the Vega star in the constellation Lyra will be the Big Dipper.