Major X7.1 solar flare erupts from Region 3842, producing likely Earth-directed CME

A major solar flare measuring X7.1 erupted from Active Region 3842 at 22:20 UTC on October 1, 2024, producing a coronal mass ejection (CME) that most likely has an Earth-directed component. This is the second-strongest solar flare of Solar Cycle 25.

• This is the second-strongest solar flare of Solar Cycle 25 — after X8.7 on May 14, 2024. The third place holds X6.3 which erupted on February 22, 2024.
• The source region is within the Earth-strike zone — meaning any CME produced by it will likely have an Earth-directed component.

A major solar flare measuring X7.1 erupted from Active Region 3842 at 22:20 UTC on October 1, 2024. The event started at 21:58 and ended at 22:29 UTC.

Associated with this event was a Type II Radio Emission with an estimated velocity of 1 246 km/s, indicating a coronal mass ejection (CME) was associated with the flare event.

Additionally, a 10cm Radio Burst (tenflare) lasting 9 minutes and with a peak flux of 810 sfu was registered from 22:09 to 22:18 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.

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

Coronagraph imagery is still not available to confirm whether we have an incoming CME. However, this region is within the Earth-strike zone — meaning any CME produced by it will likely have an Earth-directed component.

AR 3842 is currently the largest and most complex region on the solar disk, with shear occurring across the interior of its magnetic field.

The same region produced a long-duration M7.6 solar flare at 23:59 UTC on September 30, 2024. A coronal mass ejection (CME) was not produced during that event.

This is the second-strongest solar flare of Solar Cycle 25 — after X8.7 on May 14, 2024. The third place holds X6.3 which erupted on February 22, 2024.