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Short answer

Auroras happen when energetic particles, mostly electrons carried from the Sun's activity, crash into atoms and molecules high in Earth's atmosphere. The gas gets extra energy and releases it as light. [S1][S2]

Key points

• Names: aurora borealis in the north, aurora australis in the south. [S1][S2]
• Source: the Sun constantly sends out charged particles, the solar wind. When that energy builds up in Earth's magnetic field and is released, particles stream into the upper atmosphere. [S2]
• Colors: green, the most common, comes from oxygen about 100 km (60 mi) up. [S2]
• Not just Earth: auroras have been seen on Jupiter and Saturn too. [S2]

Watching for them

NOAA's Space Weather Prediction Center publishes aurora forecasts, including a 30-minute forecast. [S1]

Claims

• id: C1 claim: Auroras result from electrons colliding with the upper atmosphere. source: S1 evidence: "the result of electrons colliding with the upper reaches of Earth’s atmosphere"
• id: C2 claim: Colliding energetic particles cause the colorful glow called auroras. source: S2 evidence: "they can cause the colorful glow that we call auroras"
• id: C3 claim: Green is the most common aurora color. source: S2 evidence: "The most common color is green"
• id: C4 claim: The Sun continuously emits charged particles known as the solar wind. source: S2 evidence: "The Sun continuously produces an outflow of charged particles into the solar system"

Sources

• [S1] Aurora. NOAA SWPC. https://www.swpc.noaa.gov/phenomena/aurora . License: US government work, public domain. Accessed 2026-11-04.
• [S2] Auroras. NASA. https://science.nasa.gov/sun/auroras/ . License: US government work, public domain. Accessed 2026-11-04.

License: this note is CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Summary by iinventedlight (AI-assisted).

@misc{iil_note_wemqhx03,
  author = {{iinventedlight}},
  title = {{What causes auroras (northern and southern lights)}},
  howpublished = {iinventedlight Library},
  year = {2026},
  date = {2026-11-04},
  url = {https://iinventedlight.com/library/notes/aurora-basics/},
  note = {Permanent ID iil:note:wemqhx03. License: CC-BY-4.0.},
}

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