Why are the aurora so colorful?

The luminous principle of aurora is similar to that of neon tube. Inert gases such as neon and argon are sealed in neon tubes, and electrons run around inside. When they hit those gas atoms, the latter will be excited by light. Different atoms are excited under different conditions and emit different colors of light, so we see colorful neon lights. So is the aurora. When charged particles from the sun break into the earth's atmosphere, they will also hit different gas molecules at different heights, so they will emit different colors of aurora. Generally speaking, at an altitude of more than 200 kilometers, when charged particles hit oxygen atoms, the oxygen atoms will be excited to emit red light. At the altitude of 100~200 km, oxygen atoms will be excited to emit yellow-green light, which is the color we often see in aurora photos. Ionized nitrogen will emit blue light, and neutral nitrogen will emit purple light when hit. The color and brightness of the aurora are ever-changing, beautiful and spectacular, and it is hard to describe.

Atmospheric magnetic field and solar wind are indispensable conditions for the formation of aurora. Aurora can be divided into five types according to its shape: the arc with neat and slightly curved bottom is aurora arc; Zonal auroral zone; Aurora like a cloud; An extremely light curtain like a veil; A ray-like aurora distributed along the magnetic field lines. The colors of aurora are mainly green, red and blue, and orange, yellow, gray and white also appear. The change of the shape and color of aurora depends on the composition of solar wind particles and the energy they carry, and also depends on the density and quantity of oxygen and nitrogen molecules and atoms bombarded in the earth's atmosphere. The color of the aurora is determined by the gas in the earth's atmosphere. In the collision ionosphere, solar particles collide with oxygen and nitrogen atoms, oxygen atoms emit green and red light, and nitrogen atoms emit blue light. Of course, other gases also glow, but it is difficult for our eyes to tell. Just like colorful neon lights, we can see colorful aurora because there are many gases in the earth's atmosphere.