The National Space Weather Monitoring and Warning Center issued a red alert for geomagnetic storms at 9 a.m. on May 11: Geomagnetic storms will occur from 23 a.m. Beijing time on May 10, 2024, with the maximum level reaching the level of ultra-geomagnetic storms (Kp=9).
On the evening of May 10, photographer @Jeff took a starry sky trip in Altay, Xinjiang, to catch up with the strongest aurora event in 20 years. The super-geomagnetic storm produced brilliant and colorful auroras, and the entire northern sky was red, and the naked eye could clearly see the various aurora pillars constantly changing. In addition to red, even the rare green aurora and purple aurora also appeared.
Video source: China News Network, photographer @Jeff
Netizens around the world are also sharing the aurora they have seen.
Source: Tadpole Jun's circle of friends
What does "Kp=9" and "super geomagnetic storm" mean?
Geomagnetic storms are a typical space weather process caused by solar eruptive activity. When the Sun erupts, coronal mass ejections (CMEs) may occur. A single ejection can eject hundreds of millions of tons of solar material off the surface of the sun at high speeds of hundreds to 2,000 kilometers per second.
Schematic diagram of the influence of the Sun's energetic particle stream (solar wind) on the Earth's periphery/geomagnetic field
When the flow of high-energy particles corresponding to CME enters the range of the earth's magnetic field, the geomagnetic field will be compressed and deformed, and a large number of charged particles will be injected into the magnetosphere region, causing a sharp change in the current of the magnetospheric ring. Since the changing current produces a changing magnetic field, this part of the charged particle flow will add an additional part of the induced magnetic field to the geomagnetic field.
This additional part forms a geomagnetic disturbance, in which the disturbance reaches a certain intensity is called a geomagnetic storm.
Generally speaking, the faster the CME facing the Earth, the stronger the geomagnetic storm will be. CME also has different forms, usually measured by the angle between the two ends of the CME, and the one that is completely ringed (360°) is called halo CME, which is usually facing the Earth and has a very fast CME event, which often causes a strong geomagnetic storm event.
The intensity of geomagnetic storms is mainly classified according to specific geomagnetic indexes, which include Dst index and Kp index.
The DST index, or geomagnetic disturbance index, is an important indicator to measure space weather conditions. It reflects the intensity of a geomagnetic storm by measuring the change in the horizontal component of the Earth's magnetic field. The Kp index, or Global Magnetic Field Index, reflects the Earth's magnetic field activity every three hours. The higher the value, the stronger the corresponding geomagnetic activity.
According to the change of the Dst index, the intensity of geomagnetic storms can be divided into five levels: small magnetic storms, medium magnetic storms, large magnetic storms, very large magnetic storms, and very large magnetic storms. At the same time, the Kp index is also used to classify the intensity of geomagnetic storms. According to the change of the Kp index, the geomagnetic activity can be divided into different grades such as calm, uncalm, active, small, large, and intense.
Why are geomagnetic storms always associated with auroral observations?
On November 30 last year, the National Space Weather Monitoring and Warning Center of the China Meteorological Administration issued a geomagnetic storm warning, and geomagnetic storm activity may occur on November 30, December 1 and 2, of which geomagnetic storms above moderate or even geomagnetic storms may occur on December 1, and geomagnetic activities are expected to continue until December 2.
The aurora seen in most parts of the continent is a dull red, but green auroras can be seen in places like Mohe in the north. Source: Propaganda Department of Mohe Municipal Party Committee
At that time, auroral activity occurred in Heilongjiang, Inner Mongolia, Xinjiang and other places on the mainland, and even Beijing had clear records of auroral sightings and observations. Gorgeous aurora photos swiped the Internet, and Beijing Aurora quickly became a hot spot.
Beijing Aurora Source: Pushi
When you hear "space weather", most people will feel unfamiliar. The scope of space here is not simply outer space. Space weather actually occurs on the surface of the sun, interplanetary and even in the Earth's space environment (magnetosphere, ionosphere, thermosphere and middle and upper atmosphere), which can affect the normal operation and reliability of space-based and ground-based technology systems and endanger human activities, health and life. One of the most important sources of space weather is solar activity.
In fact, the aurora is the third "express" that the earth receives from the sun, and when a solar storm breaks out, three "expresses" will be sent to the earth.
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The first "express" is an electromagnetic wave emitted by a flare, which travels through space at a speed of about 3x108 m/s just like sunlight reaches Earth, and is delivered to Earth in just eight and a half minutes. Among them, X-rays and ultraviolet rays can affect the Earth's ionosphere, disrupting shortwave communication systems and satellite positioning services.
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On the one hand, it causes absorption in the D region of the ionosphere and hinders aeronautical communications, and at the same time, the sharp increase in high-energy protons will directly threaten the orbital operation of satellites and other artificial spacecraft.
The third "express" is a cloud of solar matter, a coronal material that is projected into the universe, and some of it takes about two or three days to reach the Earth. A large amount of coronal material travels through the universe at high speed, delivering couriers. After reaching the earth, it creates "friction" with the earth's magnetic field to create a geomagnetic storm, and the air particles in the atmosphere are "packaged" with energy, thus producing auroras.
Thus, geomagnetic storms and auroras are two of the results of the influence of these solar energetic particle flows. By monitoring the intensity of geomagnetic storm events, the intensity of the aurora can be predicted. I believe that you can feel that behind the gorgeous aurora is actually the visit of the sun's great energy. The sun's activity, which is 150 million kilometers away, may seem to have nothing to do with us, but in fact it is affecting our lives all the time.
What are the effects of geomagnetic storms on the Earth? What are we going to do?
Geomagnetic storms have an impact on both human society and the natural environment.
For human-tech systems, it can lead to power system disruption or equipment damage. At the same time, geomagnetic storms can also affect the Earth's ionosphere, which in turn can lead to problems such as communication disruption and navigation failure. In addition, geomagnetic storms may also increase the density of the upper atmosphere, increase the flight resistance of satellites and space stations, lead to a decrease in their orbital altitude, and shorten their in-orbit lifetime.
Geomagnetic storms are also exerting their unique influence in climate and ecosystems, feeding energy from the sun into the Earth's atmosphere. For example, when a geomagnetic storm occurs, the upper atmosphere is affected by both Joule heating and the deposition of energetic particles, which in turn causes changes in the temperature, density and structure of the upper atmosphere, and affects the whole world with atmospheric circulation.
In addition, geomagnetic storms can affect animals that rely on geomagnetic fields for navigation, such as carrier pigeons that fly home from hundreds of kilometers away, and when encountering geomagnetic storms, the geomagnetic inclination that was originally used as a reference becomes inaccurate, just like humans are lost in navigation and are lost in the road.
In order to alleviate the impact of solar activities on human society, scientific and technological workers in the field of space science on the mainland have made many achievements in scientific research and business.
On the one hand, space solar monitoring satellites such as Fengyun-3E, Xihe, and Kuafu-1 have been launched, which have greatly improved the mainland's space solar monitoring capabilities. On the other hand, we should vigorously develop space weather numerical prediction technology and improve forecasting and early warning capabilities. Many of the results have played a key role in serving continental space missions and ICAO's space weather services.
Fengyun-3E solar polar ultraviolet band monitoring map
Image source: National Satellite Meteorological Center (National Space Weather Monitoring and Warning Center)
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Supported by: Beijing Meteorological Society, National Satellite Meteorological Center (National Space Weather Monitoring and Warning Center)
Audit Expert: Han Dayang, Senior Engineer and Science Popularization Expert of the National Satellite Meteorological Center (National Space Weather Monitoring and Early Warning Center).
Editor-in-charge: Dong Xiaoxian