“Aurora” (Aurora) also known as “northern lights” and “Southern Lights” is one of the most beautiful natural phenomena. Tourists from around the world flock to see the colorful lights dancing in the night sky. This phenomenon is the result of a complex physical process. It starts from the Sun and travels through space for over 145 million km before reaching Earth.
birth of aurora
“sun” emits a continuous stream of solar particles known as the “solar wind” at speeds of approximately 1.6 million km per hour. At certain times, violent explosions occur on the surface of the Sun from areas known as “dark spots,” areas where magnetic fields are concentrated up to 1,000 times higher than normal. The concentration of magnetic fields in this area is Prevents the heat from the sun from reaching the surface. As a result, these spots are lower in temperature than the surrounding area and appear as dark spots.
“Corona mass spraying” (Coronal Mass Ejection or CME) An explosion that releases a huge cloud of plasma and magnetic fields into space. It is the key activity that drives Aurora. When these particles move closer to the Earth, The Earth’s magnetic field acts as a shield. and attracts charged particles to flow along magnetic lines of force towards the North and South Poles
When high-energy particles collide with atoms and molecules in Earth’s atmosphere, This will cause these particles to heat up. until it glows by atoms that gain excess energy from collisions It releases energy in the form of light particles called “Photon” (Photons) and when a large number of photons are released simultaneously Thus resulting in the aurora light that we can see.
At the same time, the solar wind stretches Earth’s magnetic field lines towards the dark side, creating a “magnetic tail” (Magnetotail) When the stretched magnetic field lines become unstable and break apart. It bounces back and accelerates the particles as they enter Earth’s atmosphere about 12,875 km above the surface. This process creates a continuous transfer of energy, similar to a game of pinball. Until those particles collide with gases in the lower atmosphere.
The colors of the auroras are determined by the type of reacting gas and the altitude at which the collision occurred. If oxygen gas is stimulated at an altitude between 97-240 km, it will give a green light. But if oxygen is stimulated at altitudes above 240 km and above where it has a low density The light will appear dark red. which is a color that is more difficult to find and are usually only visible during periods of intense solar activity.
Nitrogen gas appears in shades of blue, violet or pink. Blue and violet appear at altitudes above 97 km, while pink appears at altitudes below 97 km.
These color differences help scientists determine whether At what altitude in the atmosphere does activity occur? Camera lenses are often more sensitive to light than the human eye. This makes aurora photographs often appear brighter than what is visible to the naked eye.
Aurora Effects
Normally, the northern lights are only visible near the “Arctic Circle” or in the case of the Northern Lights It will be visible around Antarctica. But for the end of the period “Solar cycle” (Solar cycle) the cycle of changes in the sun’s activity. It has a period of approximately 11 years and is a period of powerful sunspots and solar flares. Will be able to see further.
For example, in 2024 a Category 5 geomagnetic storm was the strongest in 20 years, making aurora visible as far away as Florida, the Bahamas and India, making it the most widespread in 500 years.
According to researcher Katie Hurlingshaw, “When more solar energy comes in The aurora ovals at the north and south poles will expand.”
Auroras are not dangerous to humans on the ground. This is because the Earth’s atmosphere acts as a shield to protect us from radiation. But the geomagnetic storm This causes auroras to be dangerous to astronauts due to direct radiation. These storms can also affect modern technology, such as disrupting the operation of satellites, GPS navigation systems, and cell phone communications. Including the risk of disrupting the electrical network system.
Earth’s history has recorded that auroras and solar storms have had an impact on Earth, such as the Carrington Event in 1859. Large solar storms disrupted telegraph systems and railway signals. To assess the intensity and distortion of the Earth’s magnetic field. Scientists have measured the strength of geomagnetic storms on a scale of 0-5, so studying auroras helps scientists understand. “Space weather” and can plan to prevent damage to infrastructure
Auroras can also affect the ozone layer in the polar regions, said atmospheric physicist Noura Partamis. It states that high-energy protons from the sun can cause stratospheric ozone depletion of up to 50-70% in some cases, although this damage can be reversed naturally within a few weeks. But the ozone layer is also extremely important in protecting the earth from the sun’s harmful rays.
The Aurora phenomenon is not limited only to Earth. In March 2024, NASA’s Perseverance spacecraft detected a green aurora. caused by a solar storm on the surface of Mars for the first time This is because Mars does not have a magnetic field covering the entire planet like Earth. Auroras on Mars appear to spread across the sky.
Image credit: NASA/JPL-Caltech/Cornell Univ./Arizona State Univ/EW Knutsen
The discovery of auroras on Mars has helped scientists understand more about the planet’s environment. To prepare for the safety of future astronauts, Katie Stack Morgan from NASA stated, “Understanding the aurora borealis and conditions around Mars is extremely important. As we prepare to transport our human explorers there safely.”
Meanwhile The aurora borealis has inspired legends and legends for over 3,000 years. The ancient Norse believed that these lights were The reflection of the Valkyrie’s armor. Or is it the Bifrost Bridge that connects the mortal world to the gods’ realm? While the Finns call it “Fire Fox”, imagining a legendary fox running and flicking its tail until it creates fire in the sky. Others believe that these lights are the spirits of ancestors worthy of respect.
Aurora is a phenomenon that is both a natural beauty and an indicator of the sun’s powerful activity. Even though it has the potential to interfere with communication systems and the ozone layer, But Aurora research is also key to improving the safety of future space exploration and technology. As long as there is proper monitoring Humans on the ground can still safely enjoy this gift from the sun.
Sources: BBC, DW, Sky at Night Magazine, The Washington Post
