Contents
How Do Auroras Form?
The Sun continuously emits a stream of charged particles called the solar wind.
When these particles interact with Earth's magnetic field, a portion is guided down near the two magnetic poles. Here, they collide with oxygen atoms and nitrogen molecules in the atmosphere, exciting the gas particles.
When returning to their normal state, they emit light that forms an aurora.
Why Do Auroras Have Multiple Colors?
The colors depend on the type of gas and the altitude where the collisions occur.
Green
- Emitted by oxygen atoms.
- Most commonly seen.
- Typically at altitudes of about 100 to 150 km.
Red
- Also produced by oxygen atoms.
- Usually appears above 200 km.
- Rarer than green.
Purple and blue
- Emitted by nitrogen molecules and nitrogen ions.
- Appears at lower altitudes.
Because each type of gas glows at a different altitude, auroras often feature multiple stacked layers of color.
Why Do Auroras Usually Appear Near the Poles?
Earth's magnetic field guides charged particles toward the regions near the North and South Poles.
Therefore, auroras usually appear in regions called auroral ovals, which surround the planet's magnetic poles.
During strong solar storms, the auroral oval can expand to lower latitudes than usual.
Why Are Auroras Almost Never Visible in Vietnam?
Vietnam is located near Earth's magnetic equator, making it very far from the typical auroral zone.
Even during the strongest recorded geomagnetic storms, auroras very rarely reach latitudes as low as Vietnam.
Are Auroras Only Found on Earth?
No.
Many other planets in the Solar System also have auroras:
- Jupiter has the strongest auroras in the Solar System.
- Saturn exhibits auroras in its polar regions.
- Uranus and Neptune also have auroras.
- Mars still has auroras despite lacking a global magnetic field.
Auroras and Solar Activity
The frequency of auroras increases when solar activity is stronger.
During periods of major solar or geomagnetic storms, auroras can become brighter, wider, and appear in regions further from the poles than usual.
🌌 An aurora is not light shining down from the Sun to Earth, but rather light emitted by Earth's atmosphere itself. Every vibrant band of color in the sky is the trace of an interaction between the solar wind, magnetic fields, and atoms in our planet's atmosphere.
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References
- [1]Discovery of H₃⁺ and infrared aurorae at Neptune — Nature Astronomy (qua sứ mệnh JWST của NASA/ESA) (2025)
- [2]Đo trực tiếp dòng electron gây phát xạ tia X kiểu cực quang tại Sao Thuỷ trong lần bay ngang đầu tiên của BepiColombo — Nature Communications (qua sứ mệnh BepiColombo của ESA) (2023)
- [3]New science in plain sight: Citizen scientists lead to the discovery of optical structure in the upper atmosphere — Science Advances 4, eaaq0030 (2018)
- [4]On the Origin of STEVE: Particle Precipitation or Ionospheric Skyglow? — Geophysical Research Letters 45, 7968 (2018)
- [5]Low-latitude Aurorae during the Extreme Space Weather Events in 1859 — The Astrophysical Journal 869, 57 (2018)
- [6]Origins of the Earth's Diffuse Auroral Precipitation — Space Science Reviews 200, 205 (2016)
- [7]Discovery of an aurora on Mars — Nature 435, 790 (2005)
- [8]Semiannual variation of geomagnetic activity — Journal of Geophysical Research 78, 92 (1973)
- [9]Some problems concerning the morphology of auroras and magnetic disturbances at high latitudes — Geomagnetism and Aeronomy 3, 183 (1963)
- [10]Sunspot Number — chuỗi số vết đen và trung bình trượt 13 tháng — SILSO, Royal Observatory of Belgium (2026)
- [11]Solar Cycle Progression — NOAA Space Weather Prediction Center (2026)
- [12]Magnetic Field Calculators (IGRF/WMM) — tra vĩ độ địa từ theo toạ độ — NOAA National Centers for Environmental Information (2025)
- [13]G5 Conditions Observed — cơn bão địa từ ngày 10–11 tháng 5 năm 2024 — NOAA Space Weather Prediction Center (2024)
- [14]Atomic Spectra Database — xác suất chuyển mức của các vạch O I 557,7 nm và 630,0 nm — National Institute of Standards and Technology (2024)
- [15]Geomagnetic Storms — thang G, tác động lên lưới điện và vệ tinh — NOAA Space Weather Prediction Center (2024)
- [16]NASA, NOAA: Sun Reaches Maximum Phase in 11-Year Solar Cycle — NASA (2024)
- [17]Juno và Cassini — quan sát cực quang của Sao Mộc và Sao Thổ — NASA Science (2024)
- [18]MAVEN — quan sát cực quang khuếch tán và cực quang proton trên Sao Hoả — NASA Science (2024)
- [19]Auroras — tổng quan cơ chế và gió Mặt Trời — NASA Science / NOAA Space Weather Prediction Center (2024)
- [20]Cực quang là gì và tại sao nó xuất hiện? — Thiên văn Việt Nam (VACA) — Đặng Vũ Tuấn Sơn (2011)
- [21]Physics of the Aurora and Airglow — cơ chế kích thích, phát xạ và các vạch bị cấm của oxy — American Geophysical Union (1995)
Image: Federico Di Dio photography - Unsplash
