The cause of aurora

Aurora is produced by the excitation (or ionization) of molecules or atoms in the upper atmosphere by the high-energy charged particle flow of the earth's magnetosphere and the sun (solar wind).

Aurora is a colorful plasma phenomenon, which appears because the charged particle flow of the sun (solar wind) enters the earth's magnetic field, and bright and beautiful glow appears in the sky near the north and south poles of the earth at night. It is called the Southern Lights in Antarctica and the Northern Lights in the Arctic. Aurora is produced by the high-energy charged particle flow (solar wind) from the earth's magnetosphere or the sun exciting (or ionizing) molecules or atoms in the upper atmosphere.

According to the study of the distribution of aurora, the shape of aurora is not a circle with the geomagnetic pole as the center, but an ellipse. The spectral range of aurora is about 3 100 ~ 6700 angstroms, and the most important spectral line is the oxygen atom green line of 5577 angstroms, which is called the aurora green line.

Conditions for viewing the aurora

1, aurora index

The most common method to predict aurora is to measure it with KP index. KP is divided into ten grades, from 0 to 9. The greater the KP value, the greater the intensity of the aurora, and the wider the range of the aurora can be seen. Generally speaking, when KP=3, the aurora is active, and when KP > 5, it is considered that the aurora erupts.

2. Meteorological conditions

Aurora activity index and cloud cover are important factors affecting aurora on that day. Although the aurora may not be observed in sunny days, it is obvious that the clouds are thin and will not block the aurora, so we must choose cloudless weather in Wan Li.

3. Environmental factors

Theoretically, it is possible to see the aurora in all areas of the aurora belt, but if you want to see the aurora clearly, the sky must be dark enough, so it is best to see the aurora in the suburbs far away from the city's light pollution. In addition, moonlight is also a factor affecting the aurora, so watch the aurora and avoid the full moon.