What! Can we see the Northern Lights in the country?

I believe everyone has seen photographs of the aurora - in the long polar nights, light, colorful ribbon-like beams of light roll and float in the sky, flickering and emitting colorful light.

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When you are enjoying these wonderful aurora photography works, have you ever thought about this: where do such beautiful aurora come from? Today, let's talk about this question in detail.

01

How are the auroras formed?

The appearance of aurora is inseparable from solar activity. The sun is a huge and hot ball of gas, and nuclear reactions of various chemical elements are taking place inside and on its surface, producing a powerful stream of charged particles. These charged particle streams are emitted from the sun and shoot into the surrounding space at great speeds. When this stream of charged particles enters the thin high-altitude atmosphere outside the earth, it will violently collide with the atoms in the atmosphere, thus producing a luminous phenomenon, which is called aurora.

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You would never have thought that the sun, which is so far away from us, could bring such rare things!

02

Polar limited? Why?

Auroras mostly appear near the North and South Poles. People living in mid- and low-latitude areas can only satisfy their curiosity by appreciating photographs of the auroras on the Internet.

But why is this?

We all know that the earth has a magnetic field, and the magnetic poles of the geomagnetic field are near the North and South Poles (the magnetic North Pole is at the geographic South Pole, and the magnetic South Pole is at the geographic North Pole).

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As mentioned above, the aurora is mainly caused by the flow of charged particles emitted by the sun. These charged particles from the sun are also affected by the geomagnetic field and gather near the magnetic poles. Therefore, the aurora mostly appears above the North and South Poles. The one that occurs in the South Pole is called the Southern Lights, and the one that occurs in the North Pole is called the Northern Lights. my country is in the northern hemisphere, so the only thing you can see in Northeast China and other places is the Northern Lights.

Generally speaking, auroras are rare at our latitudes. But we just learned that auroras are closely related to solar activity, and in years with strong solar activity, auroras can be seen at lower latitudes.

For example, in 1957, when the solar activity was strong, the Mohe and Huma areas in the northeastern border of my country saw rare auroras for decades: around 7 pm on March 2, 1957, a group of bright red rays of light suddenly rose up and instantly turned into an arc-shaped light band, stretching from the sky over Heilongjiang to the south of the Greater Khingan Range. On the night of September 29 to September 30 of the same year, a rare and magnificent aurora also appeared in a large area above 40 degrees north latitude in my country, reflecting the red sky in the north. People rushed to appreciate the beautiful aurora, which can be regarded as an alternative "tour"!

03

Aurora, oh Aurora, why are you colorful?

In our impression, some auroras are like tents, some are like arcs, some are like bands, and some are like rays; some are orange-red, some are purple-red; some are light in color, and some are dark in color. The sky is colorful and beautiful.

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But have you ever wondered why the aurora has so many colors and shapes?

The reason why the aurora has so many colors is actually closely related to the composition of the air. The air is composed of oxygen, nitrogen, hydrogen, neon, helium and other gases. Under the action of the charged particle flow, the light emitted by different gases is also different, so there are auroras of various shapes and colors.

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In addition, the auroras come in a variety of forms.

From the appearance: some are like light curtains, some are like light coronas, some are like light arcs, some are like light spots, some are like light bands, some are like light columns, and some are like light beams.

From the structural point of view: some have uniform flaky structures, some are obvious at the bottom and blurred at the top, some are composed of lines, and some are composed of spots.

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Judging from the outline: some have an outline below but no outline above; some have no outline at all, and only appear as a thin and transparent piece in the night sky.

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In terms of movement: some are static, some are dynamic. The movement is also varied: some are pulsating, some are like a curtain blown by the wind, some are sweeping, some are like a moving fire snake, and some are like dancing flames.

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In terms of position: some are at the zenith (such as the corona aurora), some are slightly exposed on the horizon (such as the dawn aurora). Several types of aurora can appear at the same time in one aurora, sometimes the aurora is single-layered, sometimes double-layered or even multi-layered.

It can be seen that the aurora has many colors and shapes, and it is not an easy task to "collect" them all.

Aurora, this word seems to carry infinite charm. It comes from the power of the distant deep space and travels thousands of miles to the earth, outlining a colorful picture in the pure night sky, attracting groups of travelers to overcome the severe cold and rush to the polar regions to pursue the uncanny beauty of nature.

Have you ever seen the Northern Lights?

Produced by | Science Popularization China

Author｜Weather Science Team

Producer｜China Science Expo

Submitted by: Computer Information Network Center, Chinese Academy of Sciences

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