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SESK: Stuff Everyone Should Know · sesk.info/hame-cme-travel

How soon can the fastest Earth-directed coronal mass ejections reach Earth?

15 to 18 hours for the fastest ones.

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  1. In about 8 minutes
  2. In as little as 15 to 18 hours ✔
  3. In about 3 weeks

Why: NOAA says the fastest Earth-directed CMEs can reach Earth in as little as 15 to 18 hours. Slower ones can take several days to arrive.

Huh, didn't know that: A sustained southward magnetic field in a CME favors more intense geomagnetic storming.

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What did the CME say to Earth? "I'm on my way, give or take a day."
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References

Answer: In as little as 15 to 18 hours. NOAA says the fastest Earth-directed CMEs can reach Earth in as little as 15 to 18 hours. Slower ones can take several days to arrive.

  1. NOAA SWPC Coronal Mass Ejections www.spaceweather.gov/phenomena/coronal-mass-ejections
    as little as 15-18 hours
    Checked 2026-10-11.
  2. NOAA SWPC Coronal Mass Ejections www.spaceweather.gov/phenomena/coronal-mass-ejections
    as fast as near 3000 km/s
    Checked 2026-10-11.
  3. NOAA SWPC Coronal Mass Ejections www.spaceweather.gov/phenomena/coronal-mass-ejections
    prolonged in a south-directed orientation
    Checked 2026-10-11.

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