Major X1.8 solar flare produces Earth-directed CME, impact expected late October 10

A significant, long-duration solar flare classified as X1.8 erupted from geoeffective Active Region 3848 at 01:56 UTC on October 9, 2024. The flare produced a fast-moving coronal mass ejection (CME), expected to impact Earth between late October 10 and early October 11. X-class flares are the most intense category, with X1.8 indicating a strong burst of radiation.

A Type II Radio Emission, with an estimated velocity of 5 176 km/s was detected at 01:44 UTC. Type II emissions occur in association with eruptions on the Sun and typically indicate a coronal mass ejection is associated with a flare event.

A Type IV Radio Emission was detected at 01:43 UTC. Type IV emissions occur in association with major eruptions on the Sun and are typically associated with strong coronal mass ejections and solar radiation storms.

Additionally, a 10cm Radio Burst (tenflare) lasting 174 minutes and with a peak flux of 2 700 sfu was detected from 01:36 to 04:0 UTC.

A 10cm radio burst indicates that the electromagnetic burst associated with a solar flare at the 10cm wavelength was double or greater than the initial 10cm radio background. This can be indicative of significant radio noise in association with a solar flare. This noise is generally short-lived but can cause interference for sensitive receivers including radar, GPS, and satellite communications.

The CME is expected to impact Earth between late October 10 and early October 11.

Radio frequencies were forecast to be most degraded over the Pacific Ocean at the time of the flare.

Solar proton counts started sharply rising at 02:40 UTC, as detected by NOAA satellites in geostationary orbit around Earth. High-energy particles can reach Earth anywhere from 20 minutes to many hours following the initiating solar event.

S1 – Minor solar radiation storm threshold was reached at 04:40 UTC. S1 radiation storms can have minor impacts on polar HF (high frequency) radio propagation resulting in fades at lower frequencies.

S2 – Moderate solar radiation storm threshold was reached at 07:30 UTC and the counts continued rising. S2 radiation storms occur approximately 25 times per solar cycle.

S2 radiation storms bring a range of potential impacts across biological, satellite, and communication systems. Passengers and crew aboard high-altitude flights over polar regions may experience elevated radiation exposure, though airlines can reroute flights to minimize these risks.

Satellites may experience rare single-event upsets, where electronic components temporarily malfunction due to energetic particles. Additionally, minor disturbances in high-frequency radio communications and navigation systems, particularly in the polar regions, may occur, potentially affecting both aviation and navigation operations reliant on these technologies…