CME impacts Earth sparking G4 – Severe geomagnetic storm, worldwide aurora

CME impacts Earth sparking G4 - Severe geomagnetic storm, global auroras

A full-halo coronal mass ejection (CME) produced by an Earth-facing filament eruption on April 21, 2023, impacted Earth at 17:37 UTC on April 23. The impact sparked G4 – Severe geomagnetic storm and produced vivid aurora worldwide. Geomagnetic storms of this intensity occur about 100 times per solar cycle.

Solar wind speeds abruptly increased from ~360 km/s to 400 – 500 km/s following the CME impact.

Total magnetic field strength increased from ~9 nT to 25 nT during the shock. The Bz component rotated south and maintained a far south configuration through 20:15 UTC, at which point Bz rapidly rotated northward. Solar wind speeds further increased to above 600 km/s by 19:43 UTC, but low density produced sporadic measurements later.

In response to the arrival of full-halo CME, the geomagnetic field reached G4 – Severe geomagnetic storm conditions at 19:44 UTC.

G4 – Severe geomagnetic storm potential impacts:
The area of impact is primarily poleward of 45 degrees Geomagnetic Latitude.

Induced currents – Possible widespread voltage control problems and some protective systems may mistakenly trip out key assets from the power grid. Induced pipeline currents intensify.
Spacecraft – Systems may experience surface charging; increased drag on low earth orbit satellites, and tracking and orientation problems may occur.
Navigation – Satellite navigation (GPS) degraded or inoperable for hours.
Radio – HF (high frequency) radio propagation sporadic or blacked out.
Aurora – Aurora may be seen as low as Alabama and northern California.

station-k-index april 24 2023
swx-overview-large april 24 2023
solar wind april 24 2023
goes-proton-flux-5-minute april 24 2023
aurora forecast april 24 2023

The video below shows the filament eruption that caused the storm. The eruption also caused S1 – Minor solar radiation storm on April 23.

YouTube video

Solar wind parameters are expected to continue with enhanced conditions on April 24, with a decreasing trend expected during the latter half of the UTC day. A transition to negative polarity CH HSS regime is likely over April 25 – 26, causing active to unsettled conditions.

Auroras spread across Europe as far south as France with sightings from brightly-lit cities such as Berlin and Kraków, Dr. Tony Phillips reported.

Bright red auroras were even seen from China and across the United States, down to Las Vegas!


G4 – Severe geomagnetic storms occur about 100 times per solar cycle. The last one was recorded on March 24, 2023. It was the most intense geomagnetic storm in nearly 6 years.


1 Earth-facing filament eruption produces M1.7 solar flare and strong CME – The Watchers – April 21, 2023

2 Forecast Discussion Issued – 2023 Apr 24 0030 UTC – Prepared by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction Center

3 Severe Geomagnetic Storm Sparks Global Auroras – SpaceWeather – April 24, 2023

4 Unexpected G4 – Severe geomagnetic storm – The Watchers – March 23, 2023

Featured image credit: The Watchers


Commenting rules and guidelines

We value the thoughts and opinions of our readers and welcome healthy discussions on our website. In order to maintain a respectful and positive community, we ask that all commenters follow these rules:

  • Treat others with kindness and respect.
  • Stay on topic and contribute to the conversation in a meaningful way.
  • Do not use abusive or hateful language.
  • Do not spam or promote unrelated products or services.
  • Do not post any personal information or content that is illegal, obscene, or otherwise inappropriate.

We reserve the right to remove any comments that violate these rules. By commenting on our website, you agree to abide by these guidelines. Thank you for helping to create a positive and welcoming environment for all.


  1. Current physicists do not know the most important fact about auroras, although without knowing this fact, nothing valuable can be known about our planet and its true relationship with the Sun. Note that, auroras happen every day, but not with the same intensity. However, do you know why northern and southern lights become very active lately? And do you know why they can now be seen further away from the poles?

    I can come up with a good research article about this issue, but unfortunately, I am so busy with my comprehensive research work about the Sun, which will change the world upside down and will make every human who loves the scientific truth celebrate hysterically

Leave a reply

Your email address will not be published. Required fields are marked *