Question
How long does it take a coronal mass ejection to affect radio propagation on Earth?
Answer Options
- A) 28 days
- B) 14 days
- C) 4 to 8 minutes
- D) 15 hours to several days
Correct Answer: D
Explanation
A Coronal Mass Ejection (CME) is a massive burst of solar wind, magnetic fields, and plasma released from the Sun. Unlike the X-ray radiation from a solar flare (which arrives in 8 minutes, traveling at the speed of light), the charged particles released by a CME travel much slower, typically arriving at Earth between 15 hours and several days after the event.
When a CME hits the Earth’s magnetic field, it causes a geomagnetic storm, which then degrades HF propagation, especially on high-latitude paths. Predicting the arrival time and impact severity is a critical part of space weather forecasting.
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